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ELEMENTS 


OF 


PHYSIOLOGY; 


BY  A.  RICHERAND, 

'PROrESSOR  OF  THE  PACUETT  OP  MEDICISE  OF  PARIS,  SHROEOW  IN'  CHIEF  OF 
THE  HOSPITAL  OF  ST.  LOCIS,  MEMBER  OP  THE  ACADEMIES  OP 
VIENHA,  PETERSBURGH,  MADRID,  TURIN,  &C. 


FBOM  THE  FIFTH  LOJ\ri)OJV  EDITIOM,  REVISED,  CORRECTED, 
AJVD  Em, ARCED. 


Tvoifli  (rsistuYov. 


TRANSLATED  FROM  THE  FRENCH, 

BT 

G.  J.  M.  DB  LYS,  M.  D. 

MEMBER  OF  THE  ROTAE  COLLEGE  OF  SURGEONS  IN  LONDON. 


WITH  NOTES, 


BY  N.  CHAPMAN,  M.  D. 

Pi'ofessoF  of  the  Materia  Medica  in  the  University  of  Pennsylvania. 


PHILADELPHIA: 

PUBLISHED  BY  THOMAS  DOBSON  AND  SON,  AT  THE  STONE- 
HOUSE,  No.  41,  SOUTH  SECOND  STREET. 

‘ William  Fry,  Printer. 

1818. 


District  of  Pennsylvania,  to  wit; 

|»*»»»».  BE  IX  REMEMBERED,  That  on  the  first  day  of  November, 

• SEAL.J  in  the  thirty-eighth  year  of  the  Independence  of  the  United 
States  of  America,  A.  D.  1813,  Thomas  Dobson,  of  the  said 
district,  liath  deposited  in  this  office,  the  title  of  a book,  the  right  whereof 
he  claims  as  proprietor,  in  the  words  following,  to  wit: 

“Elements  of  Physiology;  by  A.  Richerand,  Professor  of  the  Faculty  of 
“ Medicine  of  Paris,  Surgeon  in  Chief  of  the  Hospital  of  St.  Louis, 
“ Member  of  the  Academies  of  Vienna,  Petersburg!!,  Madrid,  Turin, 
“ &LC.  From  the  fifth  London  edition,  revised,  cotrected,  and  enlarged. 
“ r»o9(  triavTov.  Translated  from  the  French,  by  G.  J.  M.  De  Lj's,  M.  D. 
“ Member  of  the  Royal  College  of  Surgeons  in  London.  With  Notes, 
“ by  N.  Chapman,  M.  D.  Professor  of  the  Materia  Medica  in  the  Uni- 
“ versity  of  Pennsylvania.” 

In  conformity  to  the  act  of  the  Congress  of  the  United  States,  intituled, 
“ An  act  for  the  encouragement  of  learning,  by  securing  the  copies  of 
maps,  charts,  and  books,  to  the  authors  and  proprietors  of  such  copies  dur- 
ing the  times  therein  mentioned.” — And  also  to  the  act,  entitled,  “ An  act 
supplementary  to  an  act,  entitled,  “ An  act  for  the  encouragement  of  learn- 
ing, by  securing  the  copies  of  maps,  charts,  and  books,  to  the  authors  and 
proprietors  of  such  copies  during  the  times  therein  mentioned,”  and  extend- 
ing the  benefits  thereof  to  the  arts  of  designing,  engraving,  and  etching 
historical  and  other  prints.” 

D.  CALDWELL, 

Clerk  of  the  District  of  Pennsylvania. 


TO 


THOMAS  T.  HEWSON,  M.  D. 


Mx  Dear  Sir, 

Confidently  expecting  to  be  called  to  teach  the  Insti- 
tutes of  Medicine  in  the  University  of  Pennsylvania,  I engag- 
ed with  much  ardour,  in  the  preparation  of  the  ensuing  work, 
to  serve  as  a Text  Book  to  my  lectures  on  Physiology.  But  I 
had  hardly  commenced  the  undertaking,  when  my  appointment 
to  another  Chair  took  place,  which  gave  a different  direction 
to  my  studies,  and  engrossed  nearly  all  my  leisure.  Notwith- 
standing however,  these  disadvantages,  it  may  be  perceived 
that  no  slender  contributions  have  been  made  to  the  work, 
and  Ttrust  that  some  of  the  matter  which  I have  added,  will 
not  be  deemed  wholly  superfluous. 

Nor  is  my  primary  object  entirely  defeated.  As  I must  ne- 
cessarily introduce  into  my  lectures  on  the  Materia  Medica  a 
variety  of  speculations  relative  to  the  laws  of  the  animal  eco- 
nomy, the  work  will  still  be  exceedingly  useful  to  my  class. 

In  submitting  a new  edition  of  this  system  of  Physiology 
to  the  public,  I can  not  help  believing  that  I am  rendering  an 
acceptable  service.  No  work  is  perhaps  so  generally  desidera- 
ted at  this  period,  especially  by  the  students  of  medicine  in  the 
United  States,  as  a treatise  on  Physiology,  which  should  con- 
cisely exhibit  the  existing  state  of  the  science,  enriched  as  it 
has  recently  been,  by  new  discoveries  and  improvements. 
The  present  work,  in  this  respect,  is  of  great  value.  Compa- 
red with  the  other  Elementary  Treatises  on  the  same  subject, 
it  has  a decided  superiority,  as  is  evinced  by  the  uncommonly 
favourable  reception  which  it  has  experienced  in  every  coun- 
try, where  the  science  of  which  it  treats,  is  cultivated  to  any 
extent.  Not  only  in  France,  but  in  Italy,  Spain,  Germany, 


IV 


DEDICATION. 


England,  and  the  United  States,  it  has  passed,  in  the  short  space 
of  eight  years,  through  repeated  impressions. 

I have  printed  from  the  fifth  and  latest  edition  of  the  au- 
thor, which,  to  employ  his  own  language,  was  “ carefully  re- 
vised and  corrected  in  all  its  parts,  so  as  to  render  the  work 
more  worthy  of  the  success  it  had  already  obtained.”  It  has 
indeed  been  enlarged  to  nearly  double  the  size  of  the  original 
copy,  not  as  continues  he,  “ by  idle  discourses  or  frivolous 
hypotheses,  but  by  an  accumulation  of  facts,  supporting  the 
opinions  previously  advanced,  and  by  developing  those  por- 
tions of  the  subject,  which,  from  being  heretofore  explained  in 
too  succinct  a manner,  might  be  involved  in  some  degree  of 
obscurity.” 

If  my  time  had  not  been  so  much  occupied,  certain  it  is,  that 
I could  have  made  the  notes  which  I have  attached  to  the 
work  far  more  extensive.  Brief  as  they  are,  however,  I am 
sure  with  the  usual  urbanity  of  your  disposition,  you  will  ex- 
cuse the  liberty  I have  taken  of  inscribing  the  work  to  you. 
I wished  to  prefix  your  name  to  it,  because,  in  the  circle  of 
my  friends,  there  is  no  one  who  is  better  qualified  to  judge 
of  its  merits,  or  from  whom  I could  expect  a more  indulgent 
and  discriminating  criticism.  Nor  was  I less  anxious  to  seize 
the  earliest  occasion  of  tendering  some  tribute  of  respect  to 
the  son  of  one  of  the  most  distinguished  cultivators  of  Physio- 
logy during  the  last  century. 

I am,  my  dear  Hewson, 

' Yours  very  faithfully, 

N.  CHAPMAN. 


Philadelphia,  November  1,  1813. 


PREFACE 


These  Elements  of  Physiology,  which  contain  an  abstract 
of  the  doctrines  I have  taught  for  several  years  past  in  my 
public  lectures,  are  written  on  the  model  of  the  small  work  on 
Physiology  of  the  great  and  immortal  Haller.  I am  far,  how- 
ever, from  presuming  to  say  that  I have  equalled  the  merit  of 
a work,  which,  as  is  remarked  by  a man  of  the  highest 
ability,*  gave,  when  it  appeared,  a new  aspect  to  the  science, 
and  commanded  universal  approbation.  If  these  Elements  of 
Physiology  deserve  any  preference  over  that  work,  the  ho- 
nour is  not  due  to  the  Author,  but  to  the  times  in  which  he 
writes,  enriched  by  the  progress  of  the  physical  sciences,  with 
a multitude  of  data  and  results  which  may  be  said  to  have 
rendered  Physiology  altogether  a new  science. 

It  will  be  easily  perceived  that  the  plan  I have  adopted  dif- 
fers essentially  from  that  followed  by  several  respectable  phy- 
sicians; and  that  the  treatises  on  Physiology  most  recently 
published,  resemble  the  present,  only  in  their  title.  In  com- 
bining a great  number  of  facts,  in  adding  to  those  already 
known,  the  result  of  my  own  observation  and  experience,  and 
in  connecting  them  by  a method  that  should  unite  accuracy 
and  simplicity,  I have  had  it  in  view  to  keep  a due  measure  be- 
tween those  elementary  works,  whose  conciseness  approaches 
to  obscurity  and  dryness,  and  those  in  which  the  authors, 
omitting  no  detail,  and  exhausting  in  a manner  their  subject, 
seem  to  have  written  only  for  those  who  have  leisure  or  incli- 
nation for  the  profoundest  study. 

* “ When  Haller  published  his  Primic  linete  Physiologi<e,  which  he  valued 
most  of  all  his  works,  a considerable  sensation  was  excited  in  the  schools. 
In  works  on  the  same  subject,  it  was  customary  to  find  long  dissertations, 
almost  always  void  of  proof,  extraordinary  opinions,  or  brilliant  fictions.  It 
was  matter  of  wonder,  that  in  Haller’s  work,  there  should  be  found  only  nu- 
merous facts,  precise  details,  and  direct  inferences,  &c.” — Vicq,^D’A,zyr. 


VI 


PREFACE. 


Should  any  conceive  that  the  present  undertaking  is  above 
the  capacity  of  my  age,  I will  say,  even  at  the  risk  of  a para- 
dox, that  young  men  are  perhaps  fittest  to  compose  elementary 
works;  because  the  difficulties  they  have  encountered  in  the 
study,  are  )'et  fresh  in  their  memory,  as  well  as  the  steps 
which  they  have  taken  to  overcome  them;  and  further,  be- 
cause their  recent  experience  points  out  to  them  the  defects 
and  advantages  of  the  different  methods  of  other  instructors;* 
so  that  he,  who  in  the  shortest  space  of  time,  has  carried  to 
the  greatest  extent  his  own  acquisition  of  sound  knowdedge, 
will,  in  some  respects,  be  the  best  guide  to  his  successors,  in 
the  difficult  and  perplexing  parts  of  elementary  study. 

In  the  composition  of  the  work,  I have  borne  constantlj'^  in 
mind  the  necessity  of  sacrificing  elegance  to  clearness,  which 
I know  to  be  the  most  important  merit  of  an  elementary  trea- 
tise. Further,  I have  throughout  followed,  I believe,  the  same 
arrangement  in  the  succession  of  the  subjects,  and  applied  to 
the  science  of  living  man,  the  principle  of  the  Association  of 
ideas;  a principle  so  well  developed  by  Condillac,  in  his  Trea- 
tise on  the  Art  of  Writing,  and  to  which  that  philosopher  has 
shown,  that  all  the  rules  of  the  art  are  to  be  referred.  Not- 
withstanding the  rigorous  law  to  which  I have  subjected  my- 
self, I hav'e,  after  the  example  of  the  ancients,  and,  among  the 
moderns,  of  Bordeu,  and  of  several  other  physicians  and  phy- 
siologists of  equal  celebrity,  thought  myself  justified  in  em- 
ploying, when  I felt  it  necessary,  metaphorical  expressions; 
because,  as  has  been  justly  observed  by  a writer  who  has  been, 
in  our  own  times,  an  honour  to  her  sex,  if  conciseness  do  not 
consist  in  the  art  of  reducing  the  number  of  words,  still  less 
does  it  consist  in  depriving  language  of  imagery.  The  con- 
ciseness which  is  to  be  envied  is  that  of  Tacitus,  at  once  elo- 
quent and  energetic;  and,  far  from  any  fear  that  imagery  should 
injure  that  justly  admired  compression  of  style,  figurative  ex- 

“ The  best  order  in  which  truth  can  be  set  forth,  is  that  in  which  it  might 
naturally  have  been  discovered;  for,  the  surest  method  of  instructing  others, 
is  to  lead  them  along  the  path  which  we  ourselves  have  followed,  in  our  own 
instruction.  In  this  way,  we  shall  seem  not  so  much  to  lay  before  them  our 
own  knowledge,  as  to  set  themselves  on  the  search  and  discovery  of  unknown 
truths.” — Cor.diilae. 


PREFACE. 


vil 

pressions  are,  Indeed,  those  which  comprise  in  fevrest  words 
the  greatest  sum  of  ideas.* 

Those  who  insist  on  meeting  in  a work  on  Physiology,  with 
a romance  instead  of  the  history  of  the  animal  economy,  will, 
no  doubt,  reproach  me  with  having  entirely  neglected  a great 
number  of  hypotheses,  ingenious  or  absurd,  on  the  uses  of 
organs;  with  having  omitted,  for  example,  while  speaking  of 
the  spleen,  to  mention  the  opinion  which  considers  that  viscus 
as  the  seat  of  mirth  and  laughter;  with  having  said  nothing  of 
the  opinion  of  those  authors,  who  conceive  it  to  maintain,  by 
counterpoising  the  liver,  the  equilibrium  of  the  two  hypochon- 
dria; nor  even  of  the  doctrine  of  the  ancients  who  ascribed  to 
^the  secretion  of  the  atra  bilis.  See.  To  recal  such  errors  for 
the  sake  of  elaborate  refutation,  would  be  wasting  much  pre- 
cious time  in  idle  discussions,  and  possessing,  as  Bacon  calls 
it,  the  art  of  making  one  question  bring  forth  a thousand,  by 
answers  more  and  more  unsatisfactory.  I have  chosen  to  forego 
all  such  vain  parade,  from  a clear  conviction,  that  works  of 
merit  are  as  often  distinguished  by  some  things  that  are  not  to 
be  found  in  them,  as  by  those  they  do  contain. 

Several  authors,  in  treating  of  the  science  of  man,  have  in- 
dulged themselves  in  frequent  excursion  into  the  vast  field  of 
accessory  sciences,  and  have,  without  necessity,  incorporated 
in  their  works  whole  chapters  on  air,  on  sound,  on  light  and 
other  subjects,  which  belong  to  the  department  of  natural 
philosophy  and  chemistry.  Haller  himself  is  not  entirely  free 
of  blame,  for  having  discredited  physiology  by  this  borrow- 
ed display.  I have  introduced  only  such  general  ideas  of  the 
subject,  as  were  absolutely  necessary  to  render  my  own  intel- 
ligible, and  were,  indeed,  too  closely  connected  with  it,  to 
admit  of  separation. 

One  of  the  principal  faults  of  writers  on  physiology  is,  that 
they  are  apt  to  fall  into  frequent  repetitions;  and  that  fault  is 
often  owing  to  the  difficulty  of  settling,  satisfactorily,  the  limits 
of  actions  which  are  mutually  connected  and  dependent  among 

De  la  Literature  corisidere  dans  ses  rapports  avec  les  Institutions  Sft- 
dales  par  Madame  de  Stael-Holstein,  tome  ii. 


PUEFACE. 


viii 

themselves,  and  running  into  each  other,  like  those  that  are 
carried  on  in  the  animal  economy. 

“ In  composition,  one  should  avoid  prolixity,  because  it  is 
“ fatiguing  to  the  mind;  digressions,  because  they  divert  the 
“attention;  frequent  divisions  and  sub-divisions,  because  they 
“ are  perplexing;  and  repetitions,  because  they  are  oppressive. 
“ What  has  been  once  said,  and  in  its  proper  place,  is  clearer 
“than  if  several  times  repeated  elsewhere.”*  In  following 
these  precepts,  and  they  cannot  be  too  much  attended  to,  one 
may,  it  is  true,  incur  the  risk  of  being  thought  superficial,  by 
superficial  readers,  who  form  their  opinion  of  a work  from  the 
perusal  of  a single  chapter;  but  a most  ample  compensation 
will  be  found  in  the  opinion  of  those,  who  choose  to  ||^ 
thoroughly  acquainted  with  a work,  before  they  pass  on  it 
their  final  judgment. 

After  having  stated  in  what  spirit  this  work  has  been  writ- 
ten, I may  say  something  of  the  motives  which  have  led  to  its 
publication.  I would  mention  in  the  first  place,  the  advantage 
which,  it  might  be  expected,  would  accrue  to  the  science,  and 
to  those  who  are  engaged  in  its  pursuit;  and,  in  the  next  place, 
the  satisfaction  which  study  has  in  store  for  him,  who  bestows 
on  it  the  time  he  can  snatch  from  the  laborious  practice  of  our 
art.  In  his  short  intervals  of  leisure  from  public  instruc- 
tion and  from  professional  duty,  left  to  himself  and  his  own 
thoughts;  in  the  silence  of  study,  and  in  the  calm  of  medita- 
tion, he  looks  down,  with  an  eye  of  pity,  on  those  who  drag 
on,  through  the  lowest  intrigues,  a despicable  existence,  and 
finds  his  consolation  against  the  endless  vexations  that  are 
prepared  for  him  by  supercilious  ignorance,  and  jealous  me- 
diocrity. 

* Condillac  Essai  sur  I’Origine  des  Connoissances  humaines,  seconde 
partie,  sect  Li.  chap.  iv. 


PEELIMINARY  DISCOURSE. 


Physiology*  is  the  science  of  life.  The  term  life  is 

applied  to  an  aggregate  of  phenomena,  which  manifest  them-> 
selves  in  succession,  for  a limited  time  in  organized  bodies. 
Combustion  is  likewise  only  a combination  of  phenomena; 
oxygen  unites  with  the  substance  which  is  burning,  caloric  is 
disengaged  from  it;  affinity  is  the  cause  of  these  chemical  phe- 
nomena, as  attraction  is  the  cause  of  the  phenomena  of  astro- 
nomy, and  in  the  same  manner  as  the  sensibility  and  contractility 
of  living  and  organized  bodies  are  the  primary  causes  of  all  the 
phenomena  which  such  bodies  exhibit — phenomena,  which  in 
their  union  and  aggregate  succession  constitute  life. 

The  false  notions  which  have  been  entertained  on  the  subject 
of  life,  and  the  vague  definitions  which  have  been  given  of  it, 
are  to  be  accounted  for,  by  considering  that  physiologists, 
.instead  of  regarding  life  as  a simple  result,  have  mistaken  it  for 
the  properties  of  life.  These  last  are  causes;  the  first  is  merely 
an  effect,  more  or  less  complex;  and,  as  the  spring  of  a watch, 
or  rather  the  elasticity  of  that  spring,  determines  by  the  mere 
action  of  the  wheels,  the  motion  of  the  hands  and  all  the  phe- 
nomena of  which  the  machine  is  capable;  so  the  vital  properties 
acting  by  the  organs,  produce  all  those  effects,  which  in  their 
combination  constitute  life.  These  effects  are  more  or  less 
numerous,  according  to  the  number  of  the  organs;  they  become 
more  rapid  too  in  their  succession  and  life  more  active,  with 
the  increase  of  energy  in  the  vital  properties.  Precisely  as  the 
motions  of  a watch  become  more  complicated,  stronger  or 
quicker,  according  to  the  greater  tension  of  the  spring,  or  the 
increased  number  of  the  wheels.  Sensibility  and  contractility, 
are  to  be  ranked  among  primary  causes,  of  whose  existence 
and  laws  we  acquire  a knowledge  from  observation,  but  whose 

* Anatomy  is  the  science  of  organization, 

A 


essence  eludes  our  investigation,*  and  will  probably  remain  for 
ever  beyond  its  reach. 

§ I.  OF  NATURAL  BEINGS. 

The  vast  domain  of  nature  is  divided  between  two  classes  of 
beings.  Inorganic  beings,  possessing  merely  the  common  pro- 
perties of  matter;  organic  and  living  beings,  obeying  particular 
laws,  though  subjected  to  the  general  laws  which  regulate  the 
universe.  Each  of  these  two  grand  divisions  is  naturally  divid- 
ed into  two  classes;  we  meet  with  inorganic  bodies  under  the 
form  of  elementary  substances ^ simple  and  not  capable  of  ana- 
lysis; or  else  under  the  form  of  mixed  substances,  compound, 
and  admitting  of  decomposition.  Thus,  too,  organized  beings 
exist  under  two  very  different  forms  of  life,  which  distinguish 
them  into  vegetables  and  animals. 

The  first  general  conception  with  which  we  ought  to  enter 
upon  this  comprehensive  study  of  nature,  is  the  mutual  depen- 
dence of  those  beings,  which,  in  their  co-ordinate  whole,  com- 
pose the  system  of  nature;  a dependence  which  requires  for 
each  the  simultaneous  existence  of  all.  Thus  a vegetable  derives 
its  nourishment  from  inorganic  bodies,  and  alters  their  inert 
substance,  which  is  unfit  for  the  food  of  animals,  unless  it  has 
previously  undergone  the  influence  of  vegetable  life. 

§ II.  OF  THE  ELE.MENTS  OF  BODIES. 

Another  consideration,  of  equal  importance  with  the  former, 
is  the  convertibility  of  all  those  substances  so  different  from 
one  another,  and  their  capacity  of  being  reduced  to  a small 
number  of  simple  substances,  called  elements.  The  ancient 
doctrine  of  Aristotle,  reladve  to  the  ftmr  elements,  still  pre- 
vailed in  the  schools,  with  a few  modifications,  which  it  had 
received  from  the  chemists,  when  the  “ Pneumatistsf”  demon- 

* It  would  be  wrong  to  infer,  from  our  ignorance  of  the  nature  of  the  vital 
properties,  that  physiology  is  an  uncertain  science.  Its  certainty  in  that  point 
of  view,  is  equal  to  that  of  other  parts  of  natur.al  philosophy.  The  chemist, 
who  explains  all  his  combinations  by  referring  them  to  the  principle  of 
affinity,  and  the  astronomer,  who  finds  in  attraction  the  cause  that  rules  the 
universe,  are  absolutely  ignorant  of  the  nature  of  those  properties. 

+ This  is  the  name  given  to  the  school  of  modern  chemistry,  because  it 
originated  from  the  discoveries  made  relative  to  the  nature  of  air  and  elastic 


-strated  by  their  beautiful  experiments,  that  three,  at  least,  of 
these  pretended  principles  of  bodies,  air,  water  and  earth,  far 
from  being  simple  substances,  were  evidently  formed  by  the 
union  and  combination  of  several  others;  that  atmospherical 
air,  for  example,  far  from  being  an  homogeneous  fluid,  was 
composed  of  many  different  gases,  and  that  in  its  purest  state, 
it  contains  at  least  two  very  distinct  principles,  oxygen  and 
azote;  that  water  is  a compound  of  oxygen  and  hydrogen,  and 
that  earth  contains  clay,  lime,  silex,  &c. 

We  have  seen  added  in  the  present  day,  to  the  number  of 
the  elements  or  simple  substances,  several  which  were  not  con- 
sidered as  such,  at  the  time  when  natural  philosophers,  misled 
by  erroneous  metaphysical  doctrines,  had  created  out  of  their 
imaginations,  beings  of  the  existence  of  which  they  could  find 
no  proof.  There  is  every  reason  to  believe,  that  the  number  of 
substances  not  admitting  of  decomposition,  limited  at  present 
to  forty-four,  may  hereafter  be  increased  or  diminished,  by  the 
discovery  of  new  principles  in  simple  substances,  or  of  new 
elements  in  compound  bodies,  which  have  hitherto  eluded  the 
investigation  of  chemists.  Whatever  may  be  the  success  of 
their  enquiries,  of  which  it  is  impossible  to  foresee  the  results, 
or  to  fix  the  limits,  there  is  reason  to  believe,  that  it  will  ever 
be  denied  us,  to  arrive  at  a knowledge  of  the  true  elements  of 
bodies,  and  that  many  of  those  substances,  which  the  imperfec- 
tion of  our  means  of  decomposition  or  analysis  obliges  us  to 
consider  as  such,  are  frequently  compound  substances  and  sub- 
ject to  their  laws. 

After  what  has  been  stated  on  the  elements  or  constituent 
principles  of  substances,  let  us  now  see  in  what  manner  the 
combination  of  these  elements  gives  existence  to  all  beings,  and 
what  are  the  general  dilferences  existing  among  the  great  classes 
into  which  they  are  divided. 

fluids.  It  must  be  acknowledged,  to  the  credit  of  metaphysics,  that  the  old 
errors  were  forsaken,  only  at  the  period  when  chemists  were  thoroughly 
convinced  of  this  truth,  that  every  idea  is  obtained  through  the  medium  of 
the  senses,  and  that  nothing  is  to  be  admitted  beyond  what  they  demonstrate 
in  actual  experiment. 


4 


§ III.  DIFFERENCES  BETIVEEN  ORGANIZED  AND  INORGANIZED 

BODIES. 

Much  attention  has  been  bestowed  of  late,  on  the  difference 
which  exists  between  organized  and  inorganized  bodies.  The 
latter  have  been  observed  to  be  very  different  from  those  which 
are  endowed  with  life,  in  the  homogeneous  nature  of  their 
substance,  in  the  complete  independence  of  their  molecules, 
each  of  which,  according  to  the  observation  of  Kant,  has  in 
itself  causes  to  account  for  its  peculiar  mode  of  existence,  in 
that  power  of  resisting  decomposition  which  they  owe  to  the 
simplicity  of  their  structure,  and  in  the  absence  of  those  pe- 
culiar powers  which  free  organic  bodies  from  the  absolute 
dominion  of  physical  laws.  The  multiplicity,  the  volatility  of 
their  elements,  the  necessary  union  of  fluids  and  solids,  the 
nutrition  and  development  from  the  diffusive  combination, 
while  the  growth  of  inanimate  bodies  takes  place  from  the 
mere  juxta  position  of  particles,  the  origin  of  living  bodies 
in  generation,  their  destruction  in  death,  such  are  the  characters 
which  distinguish  organized  beings  from  inorganized  sub- 
stances. We  are  about  to  enter  into  a detail  of  those  characters, 
to  appreciate  all  their  differences,  for  knowledge  is  to  be  ac- 
quired only  by  comparison;  and  the  greater  our  accuracy  in  com- 
paring, the  more  precise  and  extensive  will  be  the  knowledge  we 
obtain.  Several  modern  authors  have  proved,  that  it  is  impossi- 
ble to  obtain  an  accurate  idea  of  life,  except  by  comparing  those 
bodies  which  are  endowed  with  it,  with  those  in  which  life 
has  never  existed,  or  has  ceased  to  exist.  This  comparison,  I 
hope,  will  -be  fruitful  in  interesting  results,  and  will  furnish 
several  useful  considerations,  immediately  applicable  to  the 
knowledge  of  man. 

The  first  remarkable  difference  between  organized  and  inor- 
ganized bodies,  is  to  be  found  in  the  homogeneousness  of  the 
latter,  and  the  compound  nature  of  the  former.  Let  a block  of 
marble  be  broken,  each  piece  will  be  perfectly  similar  to  the 
rest,  there  will  be  no  differences  among  them,  but  such  as  relate 
to  size  or  shape.  Break  down  the  fragments,  each  grain  will 
contain  particles  of  carbonate  of  lime,  which  will  be  throughout 
the  same.  On  the  other  hand,  the  division  of  a vegetable  or  an 


5 


animal,  shews  parts  heterogeneous  or  dissimilar.  In  different 
parts  there  will  be  found  muscles,  bones,  arteries,  blossoms, 
leaves,  bark,  pith,  &c. 

Organized  beings  cannot  live,  or  exist  in  their  natural  condi- 
tion, unless  solids  and  liquids  enter  at  once  into  their  composi- 
tion. The  co-existence  of  these  two  elements  is  necessary;  and 
living  bodies  always  contain  a liquid  mass  more  or  less  con- 
siderable, and  incessantly  agitated  by  the  motion  of  the  solid 
and  living  parts.  It  is  in  fact  impossible  to  conceive  life  exist- 
ing, without  a complicated  combination  of  solids  and  fluids; 
and  without  admitting  in  the  former,  the  faculty  of  being  affect- 
ed by  impressions  from  the  latter,  and  the  power  of  acting  in 
consequence  of  those  impressions.  The  water  which  penetrates 
into  mineral  substances,  does  not  form  a necessary  part  of 
them,  and  one  cannot  adduce  in  proof  of  the  existence  of  liquids 
in  that  class  of  substances,  the  water  of  crystallization,  though 
intimately  combined,  and  rendered  solid  in  the  crystallized 
substances. 

These  inorganic  and  homogeneous  substances,  formed  of 
particles  similar  to  one  another,  when  resolved  by  decompo- 
sition into  their  last  elements,  possess  a great  simplicity  of 
inward  nature.  Among  them  are  ranked  all  the  substances 
which  do  not  admit  of  analysis;  the  mineral  compounds  are 
often  binary,  as  the  greater  part  of  saline  substances;  some- 
times they  are  ternary,  but  seldom  quarternary;  while  the  most 
simple  vegetable  contains  at  least  three  constituent  principles, 
oxygen,  hydrogen  and  carbon,  and  no  being  possessed  of  life, 
consists  of  less  than  four,  oxygen,  hydrogen,  carbon  and  azote. 
In  the  degree  of  composition,  nature  appears  therefore  to  rise 
in  gradations,  from  the  mineral  to  the  vegetable,  and  from  the 
latter  to  the  animal  kingdom.  The  complicated  nature  of  the 
latter,  the  multiplicity  of  their  elements  account  for  their  ten- 
dency to  alteration.  Minerals  are  not  subject  to  change,  unless 
they  are  acted  upon  by  external  causes.  Endowed  with  a vis 
inertias,  they  continue  in  one  condition  without  change.  The 
state  of  organized  bodiKHsfittcessantly  varying.  Their  internal 
parts  contain  an  active  laboratory,  in  which  a number  of  instru- 
ments are  constantl)’^  transforming  into  their  own  substance, 
nutritious  particles.  Besides  that  tendency  to  alteration  in  living 


6 


animals  and  vegetables,  when  deprived  of  life,  they  become 
decomposed,  by  a process  of  fermentation,  which  begins  in 
their  internal  parrs,  and  by  which  their  nature  is  changed  in 
proportion  to  the  complication  of  their  structure,  and  the  great- 
er number  and  volatility  of  their  constituent  principles. 

All  the  parts  of  a living  body,  whether  of  an  animal  or  a 
vegetable,  have  a natural  tendency  to  a common  object,  the 
preservation  of  the  individual  and  of  the  species;  each  of  the 
organs,  though  provided  for  a peculiar  action,  concurs  in  this 
object;  and  life  in  general,  or  life  properly  so  called,  is  the 
result  of  that  series  of  concurring  and  harmonic  actions.  On 
the  contrary,  each  part  of  an  inorganic  mass,  is  independent  of 
the  other  parts,  to  which  it  is  united,  only  by  the  force  or 
afEnity  of  aggregation.  When  such  a part  is  separated  from  the 
rest,  it  maintains  all  its  characteristic  properties,  and  differs 
only  by  its  size,  from  the  mass  to  which  it  no  longer  belongs. 

Among  animals  and  vegetables,  all  the  individuals  of  the 
same  class,  appear  to  have  been  formed  after  the  same  model; 
their  parts  are  equal  in  number,  and  resemble  each  other  in 
colour;  their  differences  are  slight  and  evanescent.  The  forms 
peculiar  to  organized  beings  are  therefore  invariably  determin- 
ed, and  when  nature  departs  from  them,  she  never  does  so,  to 
such  a degree,  as  in  the  shapes  of  minerals.  The  veins  of  mines 
are  never  precisely  alike,  as  the  leaves  of  vegetables  or  the 
limbs  of  animals.  Crystals  formed  from  similar  substances,  as- 
sume very  different  shapes  equally  distinct  and  precise.  Carbo- 
nate of  lime,  for  example,  assumes  according  to  circumstances 
the  shape  of  a rhomboid,  that  of  a six  sided  regular  prism,  that 
of  a solid,  terminated  by  twelve  scaleni  triangles,  that  of  a 
different  dodecahedron  with  pentagonal  faces,  &c.  as  may  be 
seen  at  large  in  the  writings  of  Haiiy. 

A powerful  inward  cause,  seems  to  arrange  the  constituent 
parts  of  animal  and  vegetable  bodies,  by  a determinate  rule,  in 
such  a manner  that  they  shall  present  a surface,  more  or  less 
completely  rounded.  Minerals  often  take  their  form,  from  ex- 
ternal bodies,  and  when  an  especial  force  assigns  it  to  them,  as 
in  crystals,  their  surfaces  are  flat  and  angular.  When  the  crys- 
tallization is  disturbed,  and  the  molecules  of  the  crystals  are 
driven  tumultuously  together,  the  geometrical  form  is  impaired, 


7 


the  parts  are  rounded,  which  would  have  been  terminated 
by  angles,  if  a slow  and  tranquil  crystallization  had  allowed 
of  regular  aggregation:  and  as  M.  Hatiy  has  remarked,  these 
waving  outlines,  these  roundings,  so  frequent  in  vegetables  and 
plants,  where  they  belong  to  beauty  of  form,  are,  in  minerals, 
indication  of  defects.  True  beauty,  in  these  beings,  is  characte- 
rized by  the  straight  line,  and  it  is  on  good  grounds  that  Rome 
de  Lisle*  has  said  of  this  sort  of  line,  that  it  seems  to  have  an 
especial  determination  to  the  mineral  kingdom. 

Amongst  all  the  characteristics  which  distinguish  the  two 
great  divisions  of  natural  bodies,  the  most  absolute,  and  the 
most  palpable,  is  that  which  is  drawn  from  the  manner  of 
growth  and  of  nourishment.  Inorganic  bodies  grow  only  by 
accretion,  that  is,  bv  the  accession  of  new  layers  to  their 
surface,  whilst  the  organic,  in  virtue  of  its  vital  powers,  re- 
ceives into  intimate  combination,  and  is  penetrated  and  per- 
vaded, by  the  substance  it  assimilates  to  itself.  In  animals  and 
plants,  nutrition  is  the  effect  of  an  internal  mechanism:  their 
growth,  is  a development  from  within.  In,  minerals,  on  the 
contrary,  growth  cannot  claim  the  name  of  development:  it 
goes  on  externally,  by  successive  addition  of  new  layers;  it  is 
the  same  being,  assuming  other  dimensions,  whilst  the  organic 
body  is  renewed  in  its  growth. 

Living  bodies  spring  from  a germ,  which  at  first,  was  part  of 
another  being,  from  which  it  detaches  itself,  for  the  sake  of  its 
own  development  and  growth.  From  the  first,  thev  arc  already 
aggregates.  Inorganic  bodies  have  no  germ:  they  are  made  up 
of  distinct  parts  brought  together;  they  have  no  birth,  but  a 
multitude  of  molecules,  collecting  into  one,  compose  masses  of 
various  bulk  and  figure. 

Organized  bodies  alone  can  die;  all  have  a duration,  deter- 
mined by  their  own  nature;  and  this  duration  is  not  like  that  of 
minerals,  proportioned  to  the  bulk  and  density:  for,  if  man  has 
not  the  life  of  the  oak,  whose  substance  much  exceeds  his  in 
density,  neither  does  he  equal  the  life  of  many  animals,  such  as 
fishes,  whose  flesh  is  of  inferior  consistence  to  his  own:  and  he 
lives  longer  than  the  large  quadrupeds,  though  his  bulk  is  less. 


Cristallographie,  Tom.  I.  p.  94. 


8 


\ 

Finally,  inorganic  are  essentially  distinguished  from  organic  . 
bodies,  by  the  want  of  these  peculiar  powers  or  properties  of 
living  nature;  powers,  which  uphold  the  equilibrium  of  the 
whole  system  of  nature,  as  I shall  explain  more  at  large,  when 
I have  considered  the  differences  that  mark  the  two  divisions 
of  the  organic  kingdom,  vegetables  and  animals. 

§ IV.  DIFFERENCES  BETWEEN  VEGETABLES  AND  ANIMALS. 

These  are  much  fewer,  less  absolute,  and  therefore  more 
difficult  to  establish.  There  is,  in  fact,  very  little  difference 
between  a zoophyte,  and  a plant,  and  there  is  a much  wider 
distance  in  their  internal  economy,  between  man,  who  stands  at 
the  height  of  the  animal  scale,  and  the  polypus  on  its  lowest 
line,  than  between  the  polypus  and  a plant.  There  lies  between 
organized  and  inorganic  bodies,  a space,  which  is  not  to  be 
filled  up  by  the  figured  stones,  nor  by  lithophytes,  nor  by  crystals, 
in  which  some  naturalists  have  thought,  they  saw  a beginning 
of  organization.  Whilst,  at  the  extremity  of  the  animal  chain, 
are  found  beings,  fixed,  like  plants,  on  the  spot  of  their  birth, 
sensitive  and  contractile,  like  the  sensitive  and  some  other 
plants,  and  reproduced  like  them  from  slips.  Yet  we  are  able  to 
state  some  differences,  sufiFiciently  marked,  to  assign  to  the 
vegetable  kind,  a character  of  their  own,  which  will  not  suit 
the  individuals  of  either  of  the  other  kingdoms. 

Their  nature,  more  complex  than  that  of  minerals,  is  less  so 
than  that  of  animals:  the  proportion  of  the  solids  to  the  liquids, 
is  greater  than  in  these  last:  accordingly  they  retain,  long  after 
death,  their  form  and  bulk,  only  that  they  grow  lighter.  The 
solids  are,  in  man,  nearly  a sixth  of  the  whole  body:  his  carcase, 
decomposed  by  putrefaction,  remains  a little  earth,  and  a light 
skeleton,  when  the  ground  and  the  air  have  drawn  from  it  all 
its  juices.  A tree,  on  the  contrary,  is  more  than  three  parts  of 
its  substance,  solid  wood.  It  has  been  dead  for  ages,  and  yet,  in 
our  buildings,  it  preserves  its  form  and  size,  though  by  drj’ing, 
it  has  lost  a little  of  its  weight. 

Their  constituent  principles,  as  they  are  less  in  number,  are 
also  less  diffusible.  In  fact,  azote,  which  is  predominant  in 
animal  substances,  is  a gaseous,  and  volatile  principle,  whilst 
carbon,  the  base  of  vegetable  substance,  is  fixed  and  solid.  This 


9 


circumstance,  added  to  the  smaller  quantity  of  their  liquids,' 
explains  the  long  duration  after  death,  of  vegetable  substances. 

But  of  all  the  characteristics  which  have  been  employed  in 
establishing  the  limits  of  animal  and  vegetable  nature,  there  is 
one  quite  sufficient  to  distinguish  these  two  great  classes  of 
beings,  but  wliich  has  not  yet  been  allowed  the  weight  it 
deserves. 

The  zoophyte,  which,  fixed  in  his  rocky  habitation,  cannot 
change  its  place,  confined  to  partial  movements,  which  certain 
plants  are  possessed  of,  which  besides,  has  not  that  sensitive 
unity,  so  remarkable  in  man,  and  in  the  animals,  which  nearest 
resemble  him  in  their  organization;  the  zoophyte,  whose  name 
indicates  an  animal-plant,  is  totally  separated  from  all  beings  of 
the  vegetable  kingdom,  by  the  existence  of  a cavity,  in  which 
alimentary  digestion  is  carried  on,  a cavity  by  the  surface  of 
which  is  an  absorption,  an  imbibition,  far  more  active  than  that 
which  takes  place  by  the  external  surface  of  the  body.  From 
this  shapeless  animal,  up  to  man,  nutrition  is  effected  by  two 
surfaces,  and  especially  the  internal,  whilst  in  the  plant,  nutri- 
tion, or  rather  the  absorption  of  nutritive  principles,  is  only  by 
the  external  surface. 

Every  animal  may  be  considered,  in  extreme  abstraction,  as 
a nutritive  tube,  open  at  the  extremities*;  the  whole  existence 
of  the  polypus  seems  reduced  to  the  act  of  nutrition,  as  its  en- 
tire substance  is  employed  in  the  formation  of  an  alimentary 
tube,  of  which  the  soft  parietes,  extremely  sensible  and  contrac- 
tile, are  busied  in  appropriating  to  themselves,  by  a sort  of 
absorption,  the  substances  which  are  brought  into  it.  From  the 
worm  up  to  man,  the  alimentary  canal  is  a long  tube,  open  at  the 
extremities;  at  first,  only  of  the  length  of  the  body  of  the  animal, 
not  bent  at  all  in  passing  from  the  head  to  the  tail,  and  carried 
on  towards  the  mouth,  and  towards  the  anus,  with  the  external 
covering  of  the  body,  but  soon  returning  upon  itself,  and  stretch- 
ing out  into  length,  far  beyond  that  of  the  body  which  contains  it. 

* Lacipide,  Histoire  Natiirelle  des  Poissons,  tom.  1.  There  maybe  brought, 
against  this  principle,  the  instance  of  some  zoophytes,  such  as  spunges,  Scc.j 
but  do  these  bodies  really  belong  to  the  animal  kingdom?  and  should  not  we 
be  warranted  in  rejecting  them,  by  the  want  of  the  alimentary  cavity,  the 
essential  characteristic  of  animal  existence? 

B 


10 


It  is  in  the  thickness  of  the  parietes  of  this  animated  tube,  be* 
twixt  the  mucous  membrane  that  lines  it  inwardly,  and  the  skin 
with  which  this  membrane  is  continuous,  that  all  the  organs  are 
placed,  which  serve  for  the  transmission  and  elaboration  of 
fluids,  together  with  the  nerves,  the  muscles,  in  short,  all  that 
serves  for  the  carrying  on  of  life.  As  we  rise,  from  the  white- 
blooded  animals,  to  the  red  and  cold-blooded,  from  these  to  the 
warm-blooded,  and  from  these  to  man,  we  see  a progressive 
multiplication  of  the  organs  that  are  contained  within  the  thick- 
ness of  the  parietes  of  the  canal: — if  we  follow,  on  the  other 
hand,  the  descending  scale,  we  see  this  structure  gradually  sim- 
plified, till  we  arrive  at  last  at  the  polypus,  and  find  in  it  only 
the  essential  part  of  animal  existence.  The  simplicity  of  its  or- 
ganization is  such,  that  it  may  be  turned  inside  out,  and  the 
external  be  made  the  internal  surface;  the  phenomena  of  nutri- 
tion, which  are  the  whole  life  of  the  animal,  go  on,  from  the 
close  analogy  between  the  two  surfaces;  unlike  to  man  and  the 
greater  part  of  animals,  in  whom  the  skin  and  the  mucous  mem- 
branes, though  growing  into  each  other,  though  linked  by  close 
sympathies,  are  far  from  possessing  a complete  analogy  of 
structure,  or  a capacity  for  the  interchange  of  functions. 

Man,  then,  and  the  whole  animal  kind  carry  about  within 
themselves,  the  supply  of  their  subsistence;  and  absorption,  by 
an  inward  surface,  is  their  distinguishing  characteristic.  It  is  in- 
accurate to  ascribe  to  Boerhaave  the  comparison  of  the  diges- 
tive system  of  animals,  to  the  soil  in  which  plants  suck  up  the 
juices  that  feed  them,  and  the  chylous  vessels,  to  real  internal 
roots.  I find  the  same  thought  well  expressed  in  the  work  on 
humours,  which,  justly  or  falsely,  bears  the  name  of  Hippo- 
crates. ^uemadmodum  terra  arboribus^  ita  animalibus  ventri- 
culus. 

The  digestive  tube,  that  essential  part  of  every  animal,  is  the 
part  of  which  the  existence  and  action  are  the  most  independent 
of  the  concurrence  of  the  other  organs,  and  to  which  the  proper- 
ties of  life  seem  to  adhere,  if  one  may  say  so,  with  most  force. 
Haller,*^  who  has  made  so  many  and  such  interesting  inquiries 
into  the  contractile  power  of  the  muscular  organs,  examining 


Opera  minora,  3 vol.  4to. 


11 


them  under  the  two-fold  relation  of  their  irritability,  as  it  is 
more  or  less  lively,  or  more  or  less  lasting,  looks  on  the  heart, 
as  the  one  in  which  these  two  conditions  are  found  in  the  highest 
combination.  He  gives  the  second  place  to  the  intestines,  the 
stomach,  the  bladder,  the  uterus,  and  the  diaphragm,  and,  after 
these,  all  the  muscles  under  the  command  of  the  will.  I had  at 
first  admitted,  with  every  other  writer,  this  classification  of  the 
contractile  parts;  but  more  than  a hundred  experiments  on 
living  animals  have  satisfied  me,  that  the  intestines  are  always 
the  last  part  in  which  the  traces  of  life  may  be  discovered.  What- 
ever may  be  the  sort  of  death  by  which  they  are  destroyed, 
peristaltic  motions,  undulations,  are  still  continued  in  this  canal, 
while  the  heart  has  already  ceased  to  beat,  and  the  rest  of  the 
body  is  all  an  inanimate  mass.  M.  Jurine  had  already  observed 
on  the  pulex  monoculus,  that,  of  all  the  parts  of  the  body  of 
this  little  white-blooded  animal,  the  intestines  were  the  last  to 
die. 

If  the  intestinal  tube  be  the  ultimum  moriens^  if  it  be  the  last 
organ  in  which  life  lingers  and  goes  out,  it  is  to  it  we  ought  to 
direct,  in  preference,  the  stimulants  that  are  capable  of  recalling 
it  in  case  of  asphyxia.  I think  that,  after  the  blowing  of  pure  air 
into  the  lungs,  the  means  that  ought  next  to  be  attended  to,  is 
the  injection  of  acrid  and  irritating  clysters,  thrown  in  with 
force.  The  large  intestines  are  connected  with  the  diaphragm 
by  a close  sympathy,  as  is  proved  by  the  phenomena  of  fecal 
evacuation:  the  irritation  of  them  is  the  surest  means  of  accele- 
rating it;  and  this  irritation  is  the  easier,  as  the  alimentary 
canal  is  the  last  part  that  is  forsaken  by  life. 

§\.  OF  LIFE. 

After  having  thus  laid  down,  between  inorganic  bodies  and 
organized  living  beings,  and  again  between  animal  and  vege- 
table nature,  a line  of  demarcation  that  cannot  be  mistaken,  let 
us  endeavour  to  exalt  ourselves  to  the  conception  of  Life;  and, 
for  accuracy  of  thought,  let  us,  in  some  sort,  analyse  it,  by  stu- 
dying it  in  all  the  beings  of  nature  that  are  endowed  with  it.  In 
this  study,  of  which  I may  be  allowed  to  state,  in  advance,  the 
results,  we  shall  see  life  composed  at  first  of  a small  number  of 
phenomena,  simple  as  the  apparatus  to  which  it  is  given  in 


12 


cKarge;  but  soon  extending  itself  as  its  organs  or  Instruments 
are  multiplied,  and  as  the  whole  organic  machines  become  more 
complex;  the  properties  which  characterize  it  and  bear  witness 
of  its  presence,  at  first  obscure,  becoming  more  and  more  mani- 
fest, increasing  in  number  as  in  development  and  energ}’;  the 
field  of  existence  enlarging,  as  from  the  lower  beings  we  re- 
ascend to  man,  who,  of  all,  is  the  most  perfect:  and  observe, 
that  by  this  term  of  perfection,  it  is  simply  meant  that  the  living 
beings  to  which  we  apply  it,  possessed  of  more  means,  present 
also  more  numerous  results  and  multiply  the  acts  of  their  exist- 
ence; for  in  this  wonderful  order  of  the  universe,  every  being 
is  perfect  in  itself,  each  being  is  constructed  most  favourably  for 
the  purpose  it  is  to  fulfil;  and  all  is  equally  admirable,  in  living 
and  animated  nature,  from  the  lowest  vegetation  to  the  subli- 
mity of  thought. 

What  does  this  plant  present  to  us  that  springs  up,  and  grows, 
and  dies  every  year?  A being  whose  existence  is  limited  to  the 
phenomena  of  nutrition  and  reproduction;  a machine  construct- 
ed of  a multitude  of  vessels,  straight  or  tvinding,  capillary  tubes, 
through  which  the  sap  is  filtrated  and  other  juices  necessary  to 
vegetation;  these  vegetable  liquors  ascend,  generally,  from  the 
roots,  where  their  materials  are  taken  in,  to  the  summit,  where 
what  remains  from  nutrition  is  evaporated  by  the  leaves,  and 
what  the  plant  could  not  assimilate  to  itself  is  thrown  off  in 
transudation.  Two  properties  direct  the  action  of  this  small 
number  of  functions:  a latent  and  faint  sensibilitv,  in  virtue  of 
which,  each  vessel,  every  part  of  the  plant,  is  affected  in  its  own 
way  by  the  fluids  with  which  it  is  in  contact:  a contractility  as 
little  apparent,  though  the  results  prove  irrefragably  its  exist- 
ence; a contractility,  in  virtue  of  which,  the  vessels,  sensible  to 
the  impression  of  liquids,  close  or  dilate  themselves,  to  effect 
their  transmission  and  elaboration.  The  organs  allotted  to  re- 
production, animate,  for  a moment,  this  exhibition:  more  sen- 
sible, more  irritable,  they  are  visibly  in  action;  the  stamina,  or 
male  organs,  bow'  themselves  over  the  female  organ,  the  pistil, 
shake  on  the  stigma  their  fertilizing  dust,  then  straighten,  retire 
from  it,  and  die  with  the  flower,  which  is  succeeded  by  the  seed 
or  fruit. 


13 


This  plant,  divided  into  many  parts,  which  are  set  in  the 
earth  with  suitable  precautions,  is  reproduced  and  multiplied 
by  slips,  which  proves  that  these  parts  are  little  enough  depend- 
ent on  each  other;  that  each  of  them  contains  the  set  of  organs 
necessary  to  life,  and  can  exist  alone.  The  different  parts  of  a 
plant  can  live  separately,  because  life,  its  simpler  organs  and 
properties  are  diffused  more  equably,  more  uniformly,  than  in 
animals  like  man,  and  its  phenomena  are  connected  in  a less  strict 
and  absolute  dependance.  I myself  have  witnessed  a very  curi- 
ous fact,  which  confirms  what  I have  said.*  A vine,  trained 
against  the  eastern  wall  of  a forge,  shot  into  the  building  a few 
branches.  These  branches,  which  entered  by  strait  enough  pas- 
sages, were  covered  with  leaves  in  the  middle  of  the  hardest 
winters;  and  this  premature  but  partial  vegetation  went  through 
all  its  periods,  and  was  already  in  flower,  when  the  part  that 
remained  without,  was  beginning  to  bud  with  the  spring. 

If  we  pass, from  the  plant  to  the  polypus,  which  forms  the  last 
link  of  the  animal  chain,  we  find  a tube  of  soft  substance,  sensi- 
ble and  contractile  in  all  its  parts,  a life  and  an  organization  at 
least  as  simple  as  that  of  the  plant.  The  vessels  which  carry  the 

* Vegetable  life  compared  in  its  means  and  in  its  results,  to  the  life  of  ani- 
mals, would  throw  the  greatest  light  on  many  phenomena,  which  it  is  still 
difficult  for  us  to  conceive  and  to  explain.  The  treatment  of  disease  in  plants, 
for  which  as  much  would  be  gained  by  these  enquiries,  is  almost  entirely 
surgical.  When,  to  make  vegetation  more  fruitful,  the  gardener  prunes  a 
luxuriant  branch;  when  the  peasants  of  the  Cevennes,  as  M.  Chaptal  has  ob- 
served, burn  the  inside  of  their  chesnut  trees  to  stop  the  progress  of  a destruc- 
tive caries;  when  the  actual  cautery  is  applied  to  the  really  ichorous  and  foul 
ulcers  of  many  trees,  &c.  it  is  to  the  organs  of  inward  life  (or  that  which  car- 
ries on  the  process  of  assimilation),  the  only  life  of  vegetables,  that  surgery  is 
applied;  while,  on  the  contrary,  in  man  and  animals,  it  is  to  the  derangement 
of  the  external  organs  that  the  remedy  is  directed.  1 shall  conclude  this  note 
■with  an  observation  on  the  wounds  of  plants.  Like  those  of  tlie  human  body, 
they  are  much  less  dangerous  when  their  surface  is  smooth,  than  when  their 
edges  are  hacked,  torn  or  bruised.  Trees  felled  with  the  saw,  will  hardly 
shoot  up  from  the  stool,  which  always  furnishes  a better  growth  when  an  axe 
has  been  employed.  The  saw  lacerates  the  vegetable  texture,  and  its  violent 
and  distressing  action  on  the  fibres,  extending  towards  tlie  roots,  affects,  more 
or  less,  the  organiz.aion.  The  uneven  surface  of  a tree  felled  in  this  manner, 
holds  Wet,  as  injurious  to  the  trunk,  which  it  rots,  as  a too  great  quantity  of 
pus,  which  bathes  constantly  the  surface  of  a wound,  checks  the  process  of 
granulation,  and  resists  cicatrization. 


14 


liquids,  the  contractile  fibres,  the  trachem^  which  give  access  to 
the  atmospheric  air,  are  no  longer  distinctly  to  be  traced  in  this 
almost  homogeneous  substance.  There  is  no  organ  especially 
allotted  to  the  reproduction  of  the  kind.  Moisture  oozes  from 
the  internal  surface  of  the  tube,  softens  and  digests  the  aliments 
which  it  finds  there;  the  whole  mass  draws  in  nourishment  from 
it;  the  tube  then  spontaneously  contracts,  and  casts  out  the 
residue  of  digestion.  The  mutual  independence  of  parts  is  abso- 
lute and  perfect:  cut  the  creature  into  many  pieces,  it  is  repro- 
duced in  every  piece;  for  each  becomes  a new  polypus,  organiz- 
ed and  living,  like  that  to  which  it  originally  belonged.  These 
getnmiparous  animals  enjoy,  in  a higher  degree  than  plants,  the 
faculties  of  feeling  and  of  self-motion;  their  substance  dilates 
and  lengthens,  and  contracts,  according  to  the  impressions  they 
receive.  Nevertheless,  these  spontaneous  movements  do  not 
suppose,  any  more  than  those  of  the  mimosa,  the  existence  of  re- 
flexion and  will:  like  those  of  a muscle  detached  from  the  thigh 
of  a frog  and  exposed  to  galvanic  excitation,  they  spring  from 
an  impression  which  does  not  extend  beyond  the  part  that  feels 
it,  and  in  which  sensibility  and  contractility  are  blended  and 
lost  in  each  other. 

From  this  first  degree  of  the  animal  scale,  let  us  now  ascend 
to  worms.  We  have  no  longer  a mere  animated  pulp  shaped 
into  an  alimentary  tube;  parcels  of  contractile  or  muscular  fibres, 
a vessel  divided  by  several  constrictions  into  a series  of  vesicles, 
which  empty  themselves  one  into  another,  by  a movement  of 
contraction  that  begins  from  the  head,  or  the  entrance  of  the 
alimentary  canal,  and  proceeds  towards  the  tail,  which  answers 
to  the  anus,  a vessel,  from  which,  in  all  probability’,  are  sent  out 
lateral  ramifications,  a spinal  marrow  equally  knotted,  or  compos- 
ed of  a chain  of  ganglions,  stigmas,  and  tracheae,  analogous  to  the 
respiratory  organs  of  plants,  and  in  some,  even  gills:  all  shews 
clearly  an  organization  further  advanced  and  more  perfect:  sen- 
sibility and  contractility  are  more  distinct;  the  motions  are  no 
longer  absolutely  automatic;  there  are  some  which  seem  to  sup- 
pose choice.  The  worm  too,  may  be  divided  into  manv  pieces; 
each  will  become  a separate  and  perfect  worm,  a head  and  tail 
growing  to  each;  but  this  division  has  its  term,  beyond  which 
there  is  no  longer  complete  regeneration.  It  cannot,  therefore. 


15 


be  pushed  so  far  as  in  the  polypi.  The  substance  of  the  worm 
being  formed  of  elements  more  dissimilar,  it  may  be  that  too 
small  a portion  does  not  contain  all  that  is  necessary  to  consti- 
tute the  animal. 

The  crustaceous  tribes,  and  among  them  the  lobster,  disco- 
vers a more  complex  apparatus  of  organization.  Here  you  will 
find  distinct  muscles,  an  external  articulated  skeleton,  of  which 
the  separate  parts  are  moveable  upon  each  other,  distinct  nerves, 
a spinal  marrow  with  bulgings,  but,  above  all,  a brain  and  a 
heart.  These  two  organs,  though  imperfect,  assign  the  animal  to 
an  order  much  above  that  of  worms.  The  first  becomes  the  seat 
of  a sort  of  intelligence;  and  the  lobster  acts  evidently  under 
impulses  of  will,  when,  attracted  by  a smell,  it  pursues  a distant 
prey,  or  when  it  flies  a danger  discovered  to  it  by  its  eyes. 
There  are  viscera  accompanying  the  intestinal  tube,  which  give 
out  to  it  liquids  that  concur  in  alimentary  digestion.  Sensibility 
and  contractility  present  each  two  shades;  in  fact,  the  parts  of 
the  animal  are  obedient  to  the  internal  stimuli,  feel  the  impres- 
sion of  fluids,  and  contract  to  impel  them;  on  the  other  hand,  by 
its  nerves  and  locomotive  muscles,  the  lobster  places  itself  in 
connexion  with  the  objects  that  surround  it.  The  phenomena  of 
life  are  linked  together  by  a strict  necessity:  it  is  no  longer  pos- 
sible to  separate  the  creature  into  two  parts,  of  which  each  may 
continue  to  live;  there  are  but  few  parts  you  may  cut  off  without 
injury,  while  you  spare  the  central  foci  of  life.  So,  if  you  take 
off  a claw,  you  observe  soon  a little  granulation,  which  swells 
and  is  developed,  and  which,  soft  at  first,  is  soon  clothed  in  a 
calcareous  covering,  like  that  which  encloses  the  rest  of  its  body. 
This  partial  regeneration  is  frequently  to  be  seen. 

If  from  white-blooded  animals  we  go  on  to  the  red  and  cold- 
blooded, such  as  fishes  and  reptiles,  we  see  this  power  of  repro- 
duction becoming  more  and  more  limited,  and  life  more  involved 
in  organization.  In  fact,  if  you  cut  off  a part  of  the  body  of  a 
fish,  the  tail  of  a serpent,  or  the  foot  of  a frog,  the  separated 
parts  are  either  not  supplied  at  all,  or  very  imperfectly  repro- 
duced. All  these  creatures  maintain,  with  the  medium  in  which 
they  live,  relations  of  more  strict  dependence.  Gills  in  these, 
lungs  in  others,  are  added  to  a heart,  nor  are  less  essential  to  life. 
However,  the  action  of  these  chief  organs  is  not  so  frequent. 


16 


Kor  of  momentary  necessity  for  the  continuance  of  life.  The  ser- 
pent  passes  long  winters,  torpid  with  cold,  in  holes  where  he  has 
no  air,  without  breathing,  without  any  motion  of  life,  and  in  aU 
appearance  dead.  These  creatures,  like  all  reptiles,  are  able  to 
breathe  only  at  long  intervals,  and  to  suspend,  for  a time,  the 
admission  of  air,  without  risking  their  existence.  Here  the  vital 
powers  are  distinct  and  strong,  and  differ  from  those  of  the  more 
perfect  animals  and  of  man,  by  very  slight  shades:  the  heart  and 
the  vessels  of  the  fish  feel  and  act  within  him,  without  his  con- 
sciousness. Further,  he  has  senses,  nerves,  and  a brain,  from 
which  he  has  intimation  of  whatever  can  affect  him;  muscles  and 
hard  parts,  by  the  action  of  which  he  moves,  and  changes  his 
place,  adapting  himself  to  the  relations  that  subsist  between  the 
substances  around  him  and  his  own  peculiar  mode  < f existence. 

We  are  come,  at  last,  to  the  red  and  warm-blooded  animals, 
at  the  head  of  which  are  the  maminiferce  and  man.  They  are  en- 
tirely alike,  save  some  slight  differences  in  the  less  essential 
organs.  There  is  none  that  has  not  the  vertebral  column,  four 
limbs,  a brain  which  fills,  exactly'^,  the  cavity  of  the  skull,  a 
spinal  marrow,  nerves  of  two  sorts,  five  senses,  muscles,  partly 
obedient  to  the  will,  partly  independent  in  their  action;  add  to 
these,  a long  digestive  tube  coiled  upon  itself,  furnished  at  its 
mouth  with  agents  of  saliva  and  mastication;  vessels  and  ly’m- 
phatic  glands,  arteries  and  veins,  a heart  with  two  auricles,  and 
two  ventricles,  lobular  lungs,  which  must  act  incessantly  in  im- 
pregnating the  blood,  that  passes  through  them,  with  the  vital 
part  of  the  atmosphere,  which,  if  it  fail,  life  is  suspended,  or 
gone.  None  of  their  organs  live  but  while  they  partake  in  the 
general  action  of  the  system,  and  while  they  are  under  the  in- 
fluence of  the  heart.  All  die,  irrecoverably,  when  they  are  parted 
from  the  body  of  the  animal,  and  are  in  no  way  replaced;  what- 
ever some  phvsiologists  may  have  said  on  pretended  regenera- 
tion of  the  nerves,  and  some  other  parts. 

Every"  thing  that  is  important  to  life,  is  to  be  found  in  these 
animals;  and  as  the  most  essential  organs  are  within,  and  con- 
cealed in  deep  cavities,  a celebrated  naturalist  was  correct  in 
saying,  that  all  animals  are  essentially  the  same,  and  that  their 
differences  are  in  their  external  parts,  and  chiefly  to  be  observed 
in  their  coverings  and  in  their  extremities. 


17 


The  human  body,  consisting  of  a collection  of  liquids  and 
solids,  contains  of  the  former,  about  five-sixths  of  its  weight. 
This  proportion  of  the  liquids  to  the  solids  may,  at  first  sight, 
appear  to  you  beyond  the  truth:  but  consider  the  excessive  de- 
crease of  size  of  a dried  limb:  the  glutaeus  maximus,  for  example, 
becomes,  by  drying,  no  thicker  than  a sheet  of  paper.  The  li- 
quids, which  constitute  the  greatest  weight  of  the  body,  exist 
before  the  solids:  for,  the  embryo  which  is  at  first  in  a gelatinous 
state,  may  be  considered  as  fluid;  besides,  it  is  from  a liquid 
that  all  the  organs  receive  their  nourishment  and  repair  their 
waste.  The  solids,  formed  from  the  liquids,  return  to  their 
former  state,  when,  having  for  a sufficient  length  of  time,  form- 
ed a part  of  the  animal,  they  become  decomposed  by  the  nutri- 
tive  process.  Even  from  this  slight  view  of  the  subject,  fluidity 
is  seen  to  be  essential  to  living  matter,  since  the  solids  are  uni- 
formly formed  from  the  fluids,  and  eventually  return  to  their 
former  state.  Solidity  is  then  only  a transient  condition  and  an 
accidental  state  of  organized  and  living  matter,  and  this  circum- 
stance affords  to  the  humoral  pathologists  ample  opportunities 
of  embarrassing  their  opponents  with  many  objections,  not  easily 
answered.  Water  forms  the  principal  part  and  the  common 
vehicle  of  all  the  animal  fluids,  it  contains  saline  substances  in 
a state  of  solution,  and  even  animal  matter  itself  is  found  in  it 
fluid,  and  that  in  three  diflferent  conditions,  under  the  form  of 
gelatine^  of  albumine,  or Jibrine.  The  first  of  these  substances, 
solidified,  forms  the  basis  of  all  the  organs  of  a white  colour,  to 
which  the  ancients  gave  the  name  of  spermatic  organs,  such  as 
the  tendons,  the  aponeurosis,  the  cellular  tissue,  and  the  mem- 
branes. Albumine  exists  in  abundance  in  almost  all  the  hu- 
mours; the  fibrine  of  the  blood  is  the  cement  which  is  employed 
in  repairing  the  waste  of  a system  of  organs,  which,  in  point  of 
bulk,  hold  the  first  rank  among  the  constituent  parts  of  the  hu- 
man body— I mean  the  muscular  system.  The  chemists  suspect, 
and  not  without  reason,  that  the  animal  matter  passes  succes- 
sively through  the  different  states  of  gelatine,  albumine  and 
fibrine;  that  these  different  changes  depend  on  the  progressive 
animalization  of  the  animal  matter,  which,  at  first  gelatinous,  a 
hydro-carbonous  oxide,  containing  no  azote,  and  acidifiable  by 
fermentation,  becomes  more  closely  combined  with  oxygen, 

C 


18 


takes  up  azote,  so  as  to  become  albumen,  subject  to  putrefaction, 
and  finally  fibrine,  by  a. super-addition  of  the  same  principles. 

The  solid  parts  are  formed  into  different  systems,  to  each  of 
which  is  intrusted  the  exercise  of  a function  of  a certain  degree 
of  importance.  Limiting  the  term  organic  apparatus,  or  system, 
to  a combination  of  parts  which  concur  in  the  same  uses,  we 
reckon  ten,  viz. — the  digestive  apparatus,  consisting  essentially 
of  the  canal  which  extends  from  the  mouth  to  the  anus;  the  ab- 
sorbent^ or  lymphatic  system,  which  is  formed  of  the  vessels  or 
glands  of  that  name;  the  circulatory  system,  which  consists  of 
an  union  of  the  heart,  the  veins,  the  arteries  and  the  capillary 
vessels;  the  respiratory^  or  pulmonary  system;  the  glandular,  or 
secretory  system;  the  sensitive  system,  including  the  organs  of 
sense,  the  brain  and  spinal  marrow;  the  muscular  system,  or  that 
of  motion,  including  not  only  the  muscles,  but  their  tendons  and 
aponeuroses;  the  osseous  system,  including  the  appendages  of 
the  bones,  the  cartilages,  the  ligaments  and  the  synovial  capsules; 
the  vocal  system,  and  the  sexual  or  generative  system,  different 
in  the  two  sexes.  Each  of  these  organic  systems  contains  in  its 
structure  several  simple  tissues,  “ or  similar  parts,”  as  the  an- 
cients called  them;  these  tissues  in  man,  may  be  enumerated  as 
follows:  cellular  tissue^  nervous  tissue^  muscular  tissue,  besides 
that  horny  substance  which  constitutes  the  basis  of  the  epidermis, 
the  nails  and  the  hair. 

These  four  substances  may  be  considered  as  real  organic  ele- 
ments, since  with  our  means  of  analysis,  we  never  can  succeed 
in  converting  any  one  of  these  substances  into  another.  The 
cerebral  pulp  is  not  convertible  into  a horny  substance,  into  cel- 
lular substance,  or  into  muscular  fibre,  neither  can  any  one  of 
these  tissues  ever  be  converted  into  cerebral  pulp.  The  bones, 
the  cartilages,  the  ligaments,  the  tendons,  the  aponeuroses,  may, 
by  long  maceration,  be  decomposed  into  cellular  substance. 
Muscular  fibres  are  not  subject  to  that  alteration,  nor  is  the 
nervous  or  cerebral  pulp;  the  horny  substance  also  resists  that 
change.  Every  thing,  therefore,  leads  us  to  acknowledge  these 
! four  constituent  principles  in  our  organs. 

The  primiti  ve  or  simple  tissues,  variously  modified,  and  com- 
bined in  different  quantities,  and  in  various  proportions,  consti- 
tute the  substamce  of  our  organs.  Their  number  is  much  more 


19 


considerable,  according  to  Bichat,  whose  happiest  conception 
was  this  analysis  of  the  human  orga'^ization.  This  physiologist 
reckoned  in  the  human  economy,  no  fewer  than  twenty-one 
general  or  generating  tissues.  But  it  is  evident,  that  this  analysis 
is  carried  too  far;  that  the  tissues  of  which  the  skin  and  the  hair 
are  formed,  are  exactly  of  the  same  nature,  are  analogous  in 
their  properties,  and  are  nourished  in  a similar  manner;  that  the 
cellular  tissue  is  the  common  basis  of  the  osseous,  cartilaginous 
mucous,  serous,  synovial,  dermoid,  &e. 

It  must  be  confessed,  that  this  separate  consideration  of  each 
organic  tissue  has  furnished  him  with  new  ideas,  ingenious  ana- 
logies and  useful  results,  and  that  his  “ Anatomic  generale,”  in 
which  those  researches  are  contained,  is  his  chief  title  to  glory. 
That  glory  would  be  complete,  if  in  that  book,  and  yet  more,  in 
his  other  works,  he  had  done  his  predecessors,  as  well  as  his 
contemporaries,  the  justice  they  had  a right  to  expect  from  him. 

The  simple,  or  elementary  fibre,  about  which  so  much  has 
been  written,  may  be  considered  as  the  philosopher’s  stone  of 
physiologists.  In  vain,  has  Haller  himself,  in  his  pursuit  of  his 
chimera,  told  us,  that  the  elementary  fibre  is  to  the  physiologist 
what  the  line  is  to  the  geometer,  and,  that  as  all  figures  are  form- 
ed from  the  latter,  so  are  all  the  tissues  formed  from  this  fibre; 
Fibra  enim  physiologo  id  est  quod  linea  geometra^  ex  qua  nempe 
figures  omnes  oriuntur.  The  mathematical  line  is  imaginary,  and 
a mere  abstraction  of  the  mind,  while  the  elementary  fibre  is  al- 
lowed a material  or  physical  existence.  Nothing,  therefore,  can 
make  us  admit  the  existence  of  a simple,  elementary,  or  primi- 
tive fibre,  since  our  senses  shew  us,  in  the  human  organization, 
four  very  distinct  materials. 

Among  the  organs,  whether  single  or  combined  in  systems, 
which  enter  into  the  human  organization,  there  are  some  whose 
action  is  so  essential  to  life,  that,  with  the  cessation  of  that  ac- 
tion, life  at  once  becomes  extinct.  These  primary  systems,  whose 
action  regulates  that  of  all  secondary  systems,  are  as  numerous 
’m  man  as  in  the  other  warm-blooded  animals.  None  of  them 
can  act,  unless  the  heart  sends  into  the  brain  a certain  quantity 
of  blood,  vivified  by  the  contact  of  atmosphencal  air  in  the  pul- 
monary tissue.  Every  serious  wound  of  the  brain  or  heart,  every 
lasting  interruption  to  the  access  of  blood  into  the  former  of 


20 


these  organs,  is  invariably  attended  with  death.  The  oxydation 
of  the  blood,  and  its  distribution  into  all  the  organs,  is  conse- 
quently the  principal  phenomenon,  on  which  the  life  of  man  and 
of  the  most  perfect  beings  depend. 

§ VI.  OF  THE  VITAL  PROPERTIES;  SENSIBILITY  AND  CON- 
TRACTIUTY. 

By  sensibility  is  meant  that  faculty  of  living  organs,  which 
renders  them  capable  of  receiving  from  the  contact  of  other  bo- 
dies, an  impression  stronger,  or  fainter,  that  alters  the  order  of 
their  motions,  increases  or  diminishes  their  activity,  suspends, 
or  directs  them.  Contractility  is  that  other  property  by  which 
parts  excited,  that  is,  in  which  sensibility  has  been  called  into 
action,  contract  or  dilate,  in  a word,  act,  and  execute  motions.  In  - 
the  same  manner,  as  we  have  not  always  a consciousness  of  the 
impression  received  by  our  organs,  and  as,  for  example,  no 
sensation  informs  us  of  the  stimulating  impression  by  which  the 
blood  calls  the  heart  into  action,  so  it  is  by  reflection  only,  that 
we  are  induced  to  admit  the  existence  of  certain  motions;  of 
those,  for  instance,  by  which  the  humours,  when  they  have  reach- 
ed the  smallest  vessels,  become  incorporated  into  the  tissue  of 
our  organs.  These  motions,  to  make  use  of  an  ingenious  com- 
parison, resemble  those  of  the  hour-hand,  compared  with  the 
second-hand  of  a watch.  The  hour-hand  appears  motionless,  and 
yet  in  twelve  hours  it  describes  the  whole  circumference  of  the 
dial  plate,  round  which  the  other  hand  moves  in  one  minute, 
with  a motion  that  is  visible. 

In  considering  life  through  the  great  series  of  beings  that  pos- 
sess it,  we  have  seen  that  those  in  which  it  is  most  limited,  or 
rather  in  which  it  consists  of  the  least  number  of  actions  and 
phenomena,  vegetables,  for  instance,  and  animals  like  the  poly- 
pus, which  have  no  brain,  no  distinct  nervous  system,  are  at 
once  endowed  with  sensibility  and  contractility  in  all  their 
parts.  All  living  beings,  all  the  organs  which  enter  into  their 
composition,  are  impregnated,  if  we  may  be  allowed  the  expres- 
sion, with  these  two  faculties,  necessarily  co-existing,  and  which 
shew  themselves  by  internal  and  nutritive  motions,  obscure,  in- 
deed, and  to  be  distinguished  only  by  their  effects.  These  two 
faculties  appear  to  exist  in  the  degree  absolutely  required  for 


21 


enabling  the  fluids  that  pervade  all  the  parts  of  a living  body,  to 
induce  the  action  by  which  these  parts  are  to  assimilate  such 
fluids.  It  is  clear,  that  the  two  properties  of  feeling  and  of  mo- 
tion are  indispensable  to  all  the  parts  of  the  body.  They  are 
properties  universally  diffused  through  organized  and  living 
matter,  but  they  exist  without  possessing  any  peculiar  organ  or 
instrument  of  action.  Were  it  not  for  these  two  faculties,  how 
would  the  different  parts  act  on  the  blood,  or  on  the  fluid  which 
supplies  its  place,  so  as  to  obtain  from  it  the  materials  subser- 
vient to  nutrition  and  the  different  secretions?  These  faculties 
are  therefore  given  to  every  thing  that  has  life — to  animals,  to 
vegetables,  to  man  in  his  waking  hours,  or  in  his  most  profound 
«leep,  to  the  foetus,  to  the  child  that  is  born,  to  the  organs  of  the 
assimilating  functions,  and  to  those  which  connect  us  with  sur- 
rounding beings.  Both  these  faculties,  obscure,  and  inseparable, 
preside  over  the  circulation  of  the  blood,  of  the  fluids,  and,  in 
short,  over  all  the  phenomena  of  nutrition. 

Though  this  kind  of  sensibility  is  always  latent  or  concealed, 
it  is  otherwise  with  regard  to  contractility,  which  may  be  sensi- 
ble or  otherwise.  The  bone,  which  takes  up  the  phosphate  of 
lime,  to  which  it  owes  its  solidity,  exerts  that  action  without  our 
being  aware  of  its  taking  place,  except  by  its  effects:  but  the 
heart  which  feels  the  presence  of  the  blood,  without  any  con- 
sciousness, on  our  part,  of  such  sensation,  exerts  motions  that 
are  easily  perceptible,  but  over  which  we  have  no  control, 
either  to  suspend  or  accelerate  them. 

Vital  properties  in  so  weak  a degree,  would  not  have  been 
sufficient  to  the  existence  of  man  and  of  the  animals  which  re- 
semble him,  obliged  to  keep  up  multifarious  intercourse  with 
every  thing  that  surrounds  them;  thus  they  enjoy  a very  supe- 
rior kind  of  sensibility,  by  means  of  which  the  impressions 
which  effect  some  of  their  organs  are  perceived,  judged  and 
compared.  This  mode  of  sensibility  might  be  more  properly  call- 
ed perceptibility^  or  the  faculty  of  accounting  to  oneself  for  the 
emotions  which  are  experienced.  It  requires  a centre  to  which  the 
impressions  may  be  referred,  and  therefore  it  exists  only  in  the 
animals  which,  like  man,  have  a brain  or  some  organ  in  its  stead; 
so  that  the  zoophytes  and  vegetables,  wanting  that  organ,  are 


22 


equally  destitute  of  this  faculty.  The  polypi,  and  some  plants,  as 
the  sensitive,  perform  nevertheless  certain  spontaneous  motions, 
which  seem  to  indicate  the  existence  of  volition,  and  conse- 
quently of  perceptibility.  But  these  motions  are  the  result  of  an 
impression,  which  does  not  extend  beyond  the  part  in  which  it 
is  experienced,  and  in  which  sensibility  and  contractility  are 
blended. 

The  almost  latent  sensibility  of  certain  parts  of  the  body,  can- 
not be  absolutely  compared  to  that  of  vegetables;  since  those 
organs  whose  sensibility  is  so  imperfect,  manifest  in  disease  a 
percipient  sensibility,  which  shews  itself  by  acute  pain,  and  it  is 
even  sufficient  to  change  the  stimulus  to  which  they  are  accus- 
tomed, to  determine  the  occurrence  of  that  phenomenon.  Thus 
the  stomach,  on  the  parietes  of  v>  hich,  the  food  does  not  in  health 
produce  any  perceptible  impression,  becomes  the  seat  of  very 
distinct  sensation,  and  of  dreadful  pain,  when  a small  quantity 
of  poisonous  matter  is  introduced  into  it.  In  like  manner,  we 
are  notconcious  of  the  impressions  excited  in  the  parietes  of  the 
bladder  or  rectum,  by  the  collection  of  urine  or  faecal  substances, 
except  when  their  contents  have  become  sufficiently  irritating 
by  their  presence,  to  excite,  in  a certain  degree,  those  irritable 
and  sentient  cavities,  and  to  transform  their  obscure,  into  a very 
distinct  sensibility.  Is  there  not  reason  to  suspect,  that  our  un- 
consciousness, in  health,  of  the  impressions  made  on  our  organs 
by  the  fluids  which  they  contain,  depends  on  our  being  accus- 
tomed to  the  sensations  which  they  incessantly  excite?  so  that 
there  remains  but  a confused  perception,  which  in  time  disap- 
pears, and  may  we  not,  under  that  point  of  view,  compare  all 
these  organs  to  those  of  sight,  hearing,  smelling,  tasting,  and 
touching,  that  are  no  longer  irritable  by  stimulants,  to  which 
they  have  long  been  habituated? 

Two  systems  of  organs,  very  different  in  their  uses  and  in 
their  qualities,  enter  into  the  composition  of  the  human  body; 
they  are  as  two  living  and  united  machines,  the  one,  formed  by 
the  organs  of  sense,  the  nerves,  the  brain,  the  muscles,  and  the 
bones,  serves  to  maintain  its  connexion  with  external  objects; 
the  other,  destined  to  internal  life,  consists  in  the  digestive  tube, 
and  the  organs  of  absorption,  circulation,  respiration,  and  se- 


23 


cretion.*  The  organs  of  generation  in  the  two  sexes  form  a se- 
parate class,  which,  as  far  as  relates  to  the  vital  properties,  par- 
takes of  the  nature  of  the  other  two. 

By  the  organs  of  sense,  and  the  nerves  which  form  a commu- 
nication between  these  organs  and  the  brain,  we  are  enabled  to 
perceive  or  to  feel  the  impressions  made  on  us  by  external  ob- 
jects; the  brain,  the  true  seat  of  that  relative  sensibility,  which 
might  very  justly  be  termed  perceptibility ^ or  the  perceptive 
power^  when  excited  by  these  impressions,  is  able  to  irradiate 
into  the  muscles  the  principle  of  motion,  and  to  induce  the  ex- 
ertion of  their  contractility.  This  j^roperty,  which  is  under  the 
direction  of  the  will,  manifests  itself  by  the  sudden  decurtation 
of  a muscle,  which  swells,  hardens,  and  determines  the  motion 
of  those  parts  of  the  skeleton  to  which  it  is  attached.  The  nerves 
and  the  brain  are  essentially  the  oi^ans  of  these  two  properties, 
a division  of  the  former  is  attended  with  a loss  of  sentiment  and 
voluntary  motion  in  the  parts  to  which  they  are  distributed.  The 
other  kind  of  sensibility  is,  on  the  contrary,  quite  independent 
of  the  presence  of  nerves;  it  exists  in  all  organs,  although  all  do 
not  receive  nervous  filaments.  It  might  even  be  asserted,  that 
the  cerebral  nerves  are  not  at  all  essential  to  the  life  of  nutrition; 
the  bones,  the  arteries,  the  cartilages,  and  several  other  tissues, 
in  which  no  nerves  are  seen  to  enter,  are  nourished  equally  well 
with  the  organs  in  which  they  exist  in  considerable  number;  the 
muscles  themselves  will  carry  on  their  own  internal  economy, 
notwithstanding  the  division  of  their  nerves;  only,  deprived  of 
those  means  of  communication  with  the  brain,  they  can  no 
longer  receive  from  it  the  principle  of  voluntary  contraction;  in- 
stead of  that  sudden,  energetic  and  lasting  decurtation  which  the 
will  determines  in  them,  they  become  merely  capable  of  those 
quiverings  called  palpitations. 

The  anatomist  who  studies  the  nerves,  with  a view  to  ascer- 
tain their  termination,  finds  them  all  arising  from  the  brain  and 
spinal  marrow,  and  proceeding,  by  a longer  or  shorter  course, 
to  the  organs  of  motion  or  of  sensation:  let  him  take  his  scalpel 
and  dissect  one  of  our  limbs,  the  thigh,  for  instance;  he  will  see 

* Tills  doctrine,  which  I believe  originated  with  the  celebrated  Bichat,  will 
be  found  more  fully  developed  in  his  work,  entitled  “ Physiological  Reseaches 
on  I-ife  and  Death.”  Ei). 


24 


the  cords  parting  into  numerous  threads,  most  of  which  disap- 
pear in  the  thickness  of  the  muscles,  whilst  others,  after  creeping 
for  a time  about  the  cellular  tissue,  which  joins  the  skin  to  the 
aponeurosis,  end  on  the  inward  surface  of  the  skin,  of  which 
they  compose  the  texture,  and  expand  into  sentient  papillae  on 
its  surface.  The  bones,  the  cartilages,  the  ligaments,  the  arte- 
ries, and  the  veins,  all  those  parts  whose  action  is  not  under  the 
control  of  the  will,  are  without  them.  Nevertheless,  all  those 
parts,  which,  in  their  natural  state,  send  no  perceptible  impres- 
sions to  the  brain,  which  when  once  insulated,  may  be  tied  and 
cut,  without  any  sign  of  pain  from  the  animal,  and  whose  action 
the  will  does  not  control,  are  yet  endued  with  a sensibility  and 
a contractility,  which  enable  them,  after  their  own  manner,  to 
feel  and  to  act,  to  recognize  in  the  fluids  that  moisten  them, 
what  is  suited  to  their  nourishment,  and  to  separate  that  recre- 
mentitious  part  which  has  suitably  affected  their  particular  mode 
of  sensibility. 

In  confining  our  attention  then,  to  the  consideration  of  a sin- 
gle limb,  we  may  easily  satisfy  ourselves  of  the  existence  of  two 
modes  of  feeling,  as  of  two  sorts  of  motion;  a sensibility  in  virtue 
of  which,  certain  parts  can  send  up  to  the  brain,  the  impressions 
they  receive,  to  be  there  objects  of  consciousness;  and  another 
sensibility  belonging  to  all  organs  without  exception,  and  all 
that  some  of  them  possess,  which  is  sufficient  for  the  exercise  of 
the  functions  of  nutrition,  and  by  means  of  which  they  are 
evolved,  and  are  kept  up  in  their  natural  state;  two  kinds  of  con- 
tractility, appropriated  to  the  two  diflferent  kinds  of  sensibility: 
The  one,  in  virtue  of  which  the  muscles  obedient  to  the  will,  ex- 
ercise the  contractions  which  it  determines;  the  other,  indepen- 
dent of  the  will,  manifests  itself  by  actions,  of  which  we  have 
no  intimation,  any  more  than  of  the  impressions  by  which  they 
are  determined. 

The  distinction  being  fairly  laid  down  between  sensibility 
and  contractility,  it  is  easy  to  understand  the  origin  of  the  end- 
less disputes  of  Haller  and  his  followers,  about  the  parts  of  the 
body,  in  man  and  animals,  which  are  endowed  with  sensibilitj’ 
and  irritability.  All  the  organs  to  which  that  learned  physiolo- 
gist has  denied  these  properties,  as  bones,  tendons,  membranes, 
cartilages,  and  cellular  membrane,  &c.  possess  only  that  latent 


25 


sensibility,  and  that  obscure  contractility,  common  to  all  living 
beings,  and  without  which,  it  is  impossible  to  conceive  life  to 
exist.  In  a state  of  health,  they  are  utterly  incapable  of  trans- 
mitting to  the  brain  perceptible  impressions,  and  of  receiving 
from  it  the  principle  of  manifest  and  sensible  motion.  It  has 
likewise  been  a matter  of  much  dispute,  whether  sensibility  and 
contractility  are  qualities  of  nerves;  if  these  parts  are  their  only 
instruments,  and  if  their  destruction  is  attended  with  a loss  of 
these  two  vital  properties,  in  the  parts  to  which  they  are  trans- 
mitted. We  may  answer  in  the  affirmative,  as  far  as  relates  to  the 
sensibility  of  perception,  and  the  voluntary  motion  which  is  en- 
tirely subservient  to  it,  but  that  the  existence  of  nerves  is  not  at 
all  necessary  to  the  exercise  of  the  sensibility'  and  contractility 
which  are  indispensable  to  the  assimilation  of  nutrition. 

No  part  of  the  living  body  is  absolutely  insensible,  but  that 
sensibility  of  every  organ  is  so  modified,  that  it  is  not  affected 
by  the  same  stimuli.  Thus,  the  ey’e  is  insensible  to  sound,  and 
the  ear  to  light.  A solution  of  tartar  emetic,  causes  no  disagree- 
able impression  to  the  conjunctiva;  taken  into  the  stomach,  it  ex- 
cites convulsive  motions,  while  an  acid  from  which  the  stomach 
does  not  suffer,  proves  a cause  of  irritation  to  the  conjunctiva,  and 
brings  on  a violent  inflammation  of  the  eye.  In  the  same  manner, 
purgatives  pass  along  the  stomach,  without  producing  any  effect 
on  that  viscus,  but  they  stimulate  the  alimentary  canal.  Can- 
tharides  have  a specific  action  on  the  bladder;  and  mercury'  on 
the  salivary  glands.  Each  part  feels,  lives,  moves,  after  its  own 
way;  in  each,  the  vital  properties  appear  under  such  shades  and 
modifications,  that  they  may  be  looked  upon  as  so  many  sepa- 
rate members  of  the  same  family,  concurring  in  one  endeavour, 
working  for  a common  end,  consentientia  omnia  (Hipp.) 

The  faculty  of  assigning  a cause  to  the  sensations,  and  that  of 
moving  by  volition,  which  man  possesses  in  common  with  all 
animals  formed  with  a distinct  nervous  centre,  are  essentially 
bound  together.  For  suppose  a living  being,  furnished  with  lo- 
comotive organs,  but  without  sensation,  placed  in  the  midst  of 
bodies,  that  every  moment  endanger  its  existence,  without  any 
means  of  distinguishing  them,  it  will  hasten  its  own  destruction. 
If  perceptibility  could,  on  the  other  hand,  exist  independently' 
of  motion,  how  dfeadful  would  be  the  fate  of  such  sentient  be- 

D 


26 


ings,  similar  to  the  fabulous  Hamadryads,  who,  immoveabljr 
fixed  in  the  trees  of  our  forests,  received,  without  any  power  to 
shun  them,  all  the  blows  inflicted  on  their  rustic  abode.  Dreams 
place  us  sometimes  in  situations  which  give  us  a just  idea  of 
their  condition.  A certain  danger  threatens  our  existence;  an 
enormous  rock  seems  to  detach  itself,  to  roll  and  precipitate 
itself  on  our  frail  machine;  a frightful  monster  seems  to  pursue 
us,  and  opens  a yawning  mouth  to  ingulf  us.  We  struggle  to 
escape  this  imaginary  danger,  to  avoid  or  to  repel  it,  but  an  irre- 
sistible and  unknown  power,  a mighty  hand  paralyses  our 
efforts,  and  keeps  us  rooted  to  the  spot;  it  is  a situation  of  horror’ 
and  despair,  and  we  awaken  overwhelmed  with  the  uneasiness 
which  we  have  suffered. 

As  there  is  no  part  that  does  not  feel,  in  a manner  peculiar  to 
itself,  so  there  is  no  one  that  does  not  act,  move,  or  contract,  in 
a manner  peculiar  to  itself;  and  the  parts  which  have  been  found 
without  a power  of  motion  analogous  to  muscular  contractility, 
have  remained  in  that  state  of  immobility,  only  for  want  of  a 
stimulus  fitted  to  their  peculiar  nature.  Some  physiologists  say 
they  have  excited  a distinct  quivering,  in  the  mesentery  of  a frog 
and  of  a cat,  by  touching  them,  after  they  had  been  previously 
moistened  with  alcohol,  or  muriatic  acid. 

In  the  operation  for  sarcocele,=^  I have  often  perceived  that, 
while  with  my  left  hand  I supported  the  tumour,  and  with  a 
scalpel  in  the  right,  divided  the  spermatic  chord,  the  tunica  va- 
ginalis shewed  oscillatory  contractions.  It  visibly  contracts  in 
the  operation  for  hydrocele.  The  injection  of  an  irritating  fluid 
determines  evident  motions  in  the  tunica  vaginalis.  The  osseous 
tissue,  notwithstanding  the  phosphate  of  lime  with  which  it  is  in- 
crusted,  is  susceptible  of  a contraction,  whose  effects,  though 
slow,  are  nevertheless  undeniable.  After  teeth  have  been  shed 
or  extracted,  the  edges  of  the  alveolar  processes  become  thinned 

* The  contraction  of  the  membrane,  formed  by  the  expansion  of  the  cremas- 
ter muscle,  has  doubtless  assisted  in  rendering-  more  distinct  the  appearance 
in  question.  This  effect  m>ist  be  particularly  distinct,  at  the  moment  of  dividing 
the  spermatic  chord.  The  contractions  of  the  same  muscle  corrugate  the  skin 
of  the  scrotum,  when  this  part  is  exposed  to  cold,  and  draw  up  the  testicle* 
towards  the  inguinal  rings.  The  contractility  of  the  skin  of  the  scrotum  ha* 
but  little  influence  in  producing  this  effect. 


27 


from  contraction,  and  the  alveolar  cavities  disappear.  These 
facts  appear  to  me  to  prove,  still  better  than  all  the  experiments 
performed  on  living  animals,  (experiments  of  which,  by  the  bye, 
the  results  ought  not  too  confidently  to  be  applied  to  the  economy 
of  man)  what  one  should  think  of  the  assertions  of  Haller  and 
his  followers,  on  the  insensibility  and  inirritability  of  the  serous 
membranes,  and  of  the  organs  of  a structure  analogous  to  their’s. 

We  will,  at  present,  say  nothing  of  the  porosity,  of  the  divisi- 
bility, of  the  elasticity,  and  other  properties  which  are  common 
to  living  bodies  and  inanimate  substances.  These  properties  are 
never  possessed  in  their  whole  extent,  and  in  all  their  purity,  if 
that  expression  may  be  allowed.  Their  results  are  always  infiu- 
enced  by  the  vital  power,  which  constantly  modifies  the  effects 
which  seem  to  depend  most  immediately  upon  a physical, 
chemical,  or  mechanical  cause,  or  upon  anv  other  agent  what- 
soever. Not  so  with  the  truly  vital  extensibility^  which  is  so 
manifest  in  certain  organs,  as  the  penis  and  the  clitoris.  When 
exJcited,  they  become  turgid  and  dilated  by  the  afflux  of  humours, 
bat,that  effect  does  not  depend  on  a peculiar  property,  distinct 
from  sensibility  and  contractility.  These  parts  dilate,  their  tissue 
stretches  under  the  action  of  these  two  properties,  which  would 
occasion  the  same  phenomenon  in  all  other  parts,  if  their  struc- 
ture were  similar. 

The  same  applies  to  calorlcity^  or  that  power  inherent  in  all 
living  beings,  of  maintaining  the  same  degree  of  heat,  in  vary- 
ing temperatures.  In  consequence  of  which  property,  the  human 
body  preserves  its  temperature,  of  from  thirty  to  forty  degrees 
(of  Reaumur’s  scale)  under  the  frozen  climate  of  the  polar 
regions,  as  well  as  in  the  burning  atmosphere  of  the  torrid  zone. 
It  is  by  the  exercise  of  sensibility  and  of  contractility,  that  is,  by 
the,  exercise  of  the  functions  over  which  these  vital  powers  pre- 
side, that  the  body  resists  the  equally  destructive  influence  of 
excessive  heat  and  cold. 

If  one  were  to  admit  caloricity  as  one  of  the  vital  properties, 
because,  according  to  Professor  Chaussier,  that  power  of  pre- 
serving a uniform  warmth  is  a very  remarkable  phenomenon, 
one  might  be  led  to  suppose,  a distinct  cause  of  a peculiar  pro- 
perty to  operate  in  producing  other  phenomena  of  no  less  im- 
portance. 


28 


Barthez  and  Professor  Dumas  have  fallen  into  the  same  error, 
the  former,  in  wishing  to  establish  the  existence  of  a power  of 
permanent  situation  in  the  molecules  of  muscular  fibres;  the 
latter,  in  adding  to  sensibility  and  contractility  a third  property, 
which  he  terms  the  power  of  vital  resistance.  Living  muscles 
are  torn  with  much  more  difficulty  than  when  dead,  because  the 
contractility  which  these  organs  possess  in  the  highest  degree, 
is  incessantly  tending  to  preserve  the  contact  of  the  molecules, 
the  series  of  which  forms  the  muscular  fibre,  and  even  to  draw 
them  into  closer  connexion.  This  fact,  which  is  brought  forward 
as  a proof  of  the  existence  of  a peculiar  power,  is  easily  ex- 
plained, on  the  principle  of  contractility. 

Organized  and  living  bodies  resist  putrefaction,  from  the 
very  circumstance  of  their  being  endowed  with  life.  The  con- 
tinual motion  of  the  fluids,  the  re-action  of  the  solids  on  the 
fluids,  the  successive  and  continual  renovation  of  the  latter,  by 
the  reception  of  new  chyle,  their  constant  purification  by  means 
of  the  secretions,  through  which  the  products  animalized  in  ex- 
cess are  parted  with,  such  are  the  causes  which  prev'ent  the  pu- 
trefactive action  from  taking  place  in  bodies  endowed  with  life, 
notwithstanding  the  multiplicity  and  the  volatility  of  their  ele- 
ments. Their  preservation  is  therefore  a secondary  effect,  and 
depending  on  the  exercise  of  the  functions  regulated  by  sensi- 
bility and  contractility.  Nature  is  distinguished  for  deriving  a 
multitude  of  effects  from  a very  small  number  of  causes,  it 
therefore  shews  a very  imperfect  acquaintance  with  her  laws, 
to  assign  a separate  cause  to  each  fact. 

The  separation  of  the  chyle,  which  takes  place  in  the  duo- 
denum, from  the  admixture  of  the  bile  with  the  alimentary  sub- 
stance, the  vivification  of  the  blood  by  respiration,  the  secretion 
of  the  fluids  in  the  conglobate  glands,  nutrition  in  the  organs, 
are  so  many  acts  of  the  living  economy,  to  which  one  might 
feel  disposed  to  assign  distinct  causes;  but  these  chemico-vital 
processes,  are  so  subordinate  to  sensibility  and  contractility, 
that  they  are  met  with,  only  in  organs  endowed  wdth  these  two 
properties,  and  they  take  place,  in  a degree  more  or  less  per- 
fect, according  to  the  condition  of  these  properties  in  the 
organs  in  which  they  occur. 

We  have  stated  that  there  exist  two  great  modifications  of 


29 


sensibility  and  contractility;  that  sensibility  is  divided  into 
percipient  sensibility  and  latent  sensibility^  that  contractility 
is  at  times  voluntary,  at  others  involuntary^  and  that  the  latter 
may  be  perceivable  or  insensible, 

I Perceiving,  {Cerebral^  nervous^  animal  sensi- 
bility^ perceptibility.') 

With  consciousness  of  impressions  or  percep- 
tibility; it  requires  a peculiar  apparatus. 
Latent.  {^Nutritive.,  organic  sensibility.) 

Without  consciousness  of  impressions;  or,  ge- 
neral sensibility,  common  to  every  thing  that 
has  life;  it  has  no  peculiar  organ,  and  is  found 
universally  diffused  in  living  parts,  animal  or 
vegetable. 

{Voluntary  and  sentient.,  subordinate  to  per- 
ceptibility. 

Involuntary  and  insensible.,  corresponding  to 
latent  sensibility.  Tonicity. 

Involuntary  and  sentient. 

The  cause  of  this  last  modification  of  contractility,  appears 
to  depend  on  the  peculiar  organization  of  the  system  of  the 
great  sympathetic  nerves.  From  these  nerves,  the  heart,  the 
digestive  canal,  &c.  seem  to  receive  the  power  of  exerting 
sensible  contraction,  an  effect  produced  by  the  direct  appli- 
cation of  a stimulus,  and  over  which  volition  has  no  control, 
as  will  be  stated  in  speaking  of  those  nerves. 

Sensibility  and  contractility  offer  a vast  number  of  differences, 
the  principal  of  which  depend  on  the  age,  the  sex,  the  regimen, 
the  climate,  the  state  of  waking  or  of  sleep,  of  health  or  of 
sickness,  on  the  relative  development  of  the  lymphatic,  cellu- 
lar or  adipose  systems,  and  on  the  proportions  which  exist 
between  the  nervous  and  muscular  systems. 

In  the  first  place,  the  principle  of  sensibility  and  of  contrac- 
tility may,  in  its  action,  be  likened  to  a fluid  flowing  from  any 
source  whatsoever,  which  is  consumed,  repaired,  and  drained 


30 


by  use,  resupplied,  or  exhausted,  equally  distributed,  or,  occa- 
sionally concentrated  on  certain  organs. 

Secondly.  Sensibility,  like  contractility,  is  very  considerable 
at  the  instant  of  birth,  and  seems  to  diminish  more  or  less 
rapidly  till  death. 

7’hirdly.  The  liveliness  and  frequency  of  impressions  wear 
it  out  very  early.  It,  in  a manner,  repairs  itself,  that  is,  re- 
covers its  original  delicacy,  when  the  sentient  organs  have  been 
long  at  rest.  Thus,  an  epicure  whose  taste  has  grown  dull  with 
high  living,  will  recover  all  its  accuracy,  if  during  several 
months,  instead  of  spiced  ragouts  and  spirituous  liquors,  he 
lives  on  dry  bread  and  plain  water.  In  like  manner,  contractility 
becomes  exhausted  in  the  muscles  which  are  too  long  emplo)  ed, 
and  it  is  recovered  during  the  repose  of  sleep. 

Fourthly.  The  following  is  an  instance  of  the  manner  in 
which  sensibility  becomes  concentrated  on  one  organ,  and 
appears  to  forsake  the  others:  when  the  venereal  excitement 
is  in  its  highest  degree,  animals  under  its  influence,  receive 
blows  and  stings  without  pain.  Domestic  animals  in  that  condi- 
tion, are  often  ill  treated,  without  appearing  to  feel  what  is 
done  to  them.  If  the  hind  legs  of  the  toad  are  cut  off,  at  the 
time  that  he  is  holding  the  female  firmly  embraced,  and  is 
pouring  his  prolific  seminal  fluid  on  the  ova  which  are  issuing 
at  her  anus,  he  does  not  lose  his  hold,  he  seems  insensible  to 
every  other  sensation;  as  a man  who  is  taken  up  with  one 
thought,  and  absorbed  in  reflection,  is  scarcely  diverted  from 
it  by  any  means  that  can  be  employed.  When  during  the  influ- 
ence of  satyriasis,  the  vital  power  is  carried  to  excess  in  the 
penis,  patients  have  been  known,  (as  we  are  told  by  Aetius)  to 
cut  off  both  their  testicles,  without  suffering  the  pain  usually 
attending  so  severe  an  operation.  It  is  by  this  law  of  sensibility, 
that  we  are  to  explain  the  observation  of  Hippocrates,  that  two 
parts  of  the  body  cannot  be  in  pain  at  the  same  time.  If  two 
pains  come  on  at  once,  the  more  violent  prevents  the  slighter 
from  being  felt;  Ambo  partes  non  possunt  dokre  simul.  Duobus 
doloribusy  simul  orientibus,  vehementior  ebscurat  alterum.  (Hipp.) 
In  cases  of  scrophulous  swellings,  the  parts  are  observed  to  in- 
flame, to  become  painful,  and  suppuration  occurs  but  rarely  in 
every  part  at  once,  if  the  case  is  serious  and  attended  with  acute 


pain.  The  germ  of  a disease  or  of  a slighter  affection,  may 
sometimes  remain  dormant  under  a greater  pain.  I was  once 
overturned  in  a carriage,  from  the  awkwardness  of  the  coach- 
man, the  windows  were  broken  and  my  wrists  sprained.  The 
right  wrist  which  had  suffered  most,  swelled  first;  I employed 
the  proper  treatment,  and  when  at  the  end  of  a week,  the  swel- 
ling and  pain  had  almost  completely  ceased,  and  the  right  hand 
was  beginning  to  recover  its  suppleness  and  flexibility,  the  left 
wrist  swelled  and  in  its  turn  became  pained;  two  complaints,  if 
they  may  be  called  such,  appeared  in  succession,  and  separately 
went  through  their  regular  course.* 

The  perfection  of  one  sense  is  never  obtained,  but  at  the 
expense  of  another;  the  blind  who  bestow  more  attention  on  the 
sensations  communicated  by  the  sense  of  touch  and  of  hearing, 
often  astonish  us  by  the  delicacy  of  these  organs;  so  that,  as  has 
been  observed,  those  who,  to  improve  the  human  voice,  have 
dared  to  mutilate  their  fellow  creatures,  by  depriving  them  of 
the  organs  of  generation,  might  have  bethought  themselves  of 
putting  out  their  eyes,  to  render  them  more  sensible  to  the  sweet 
impressions  of  harmony. 

Fifthly.  During  sound  sleep,  the  exercise  of  the  percipient 

•John  Hunter  maintains  from  theory,  the  position  that  no  two  different 
fevers  can  take  place  at  the  same  time  in  the  constitution,  but  that  if  the  two 
causes  of  disease  exist  to.o-ether,  the  diseases  themselves  must  be  vicarious. 
And  he  verifies  his  reasoning's  from  experience. 

“ On  Thursday  the  sixteenth  of  May,  1775,  I inoculated  a gentleman’s 
child,  and  it  was  observed  that  I made  pretty  large  punctures.  On  the  Sunday 
follow'ing,  viz.  the  nineteenth,  he  appeared  to  have  received  the  infection,  a 
small  inflammation  or  redness  appearing  round  each  puncture,  and  a small 
tumour.  On  the  twentieth  and  twenty-first,  the  child  was  feverish,  but  I 
declared  that  it  was  not  the  variolous  fever,  as  the  inflammation  had  not  at  all 
advanced  since  the  nineteenth.  On  the  twenty -second,  a considerable  eruption 
appeared,  -which  was  evidently  the  measles,  and  the  sores  on  the  arms  ap- 
peared to  go  back,  becoming  less  inflamed. 

“ On  the  twenty-third  he  was  very  full  of  the  measles;  but  the  punctures  on 
the  arms  were  in  the  same  state  as  on  the  preceding  day. 

“ On  the  twenty-fifth,  the  measles  began  to  disappear,  on  the  twenty-sixth 
and  twenty-seventh,  the  punctures  began  again  to  look  a little  red.  On  the 
twenty-ninth,  the  Inflammation  increased  and  there  was  a little  matter  formed. 
On  the  thirtieth,  he  was  seized  with  fever.  The  small-pox  appeared  at  the 
regular  time,  went  through  its  usual  course,  and  terminated  favourably.” 

T.  Hunter  on  Inflammation,  p 5. 


32 


faculty,  anJ  that  of  voluntary  contractility,  are  entirely  suspencl- 
ed.  During  that  state,  it  seems  as  if  some  covering  were 
thrown  over  the  sentient  extremities.  We  know  how  hard 
the  hearing  becomes,  how  dull  the  senses  of  smell  and  taste 
become,  how  dim  the  sight,  a cloud  spreading  bef'^we  the  eves, 
the  moment  we  are  falling  asleep.  Vir  qmdam  exquisitissima 
sensibilitate  pr&ditus^  semi  consopitus  coibat;  huic  ut  si  ve/a- 
mento  levi  glans  obductus  fuisset^  sensus  voluptatis  referebatur. 

Sixthly.  Sensibility  is  more  lively,  and  more  easily  excited, 
in  the  inhabitants  of  warm  climates,  than  in  those  of  northern 
regions.  What  a prodigious  difference  there  is,  in  that  respect, 
between  the  native  of  Germany  and  of  the  southern  provinces 
of  France.  Travellers  tell  us,  that  there  are  in  the  neighbour- 
hood of  the  poles,  natives,  so  little  endowed  with  sensibility, 
that  they  feel  no  pain  from  the  deepest  wounds.  The  inhabitants 
of  the  coast  of  North  America,  if  we  may  believe  the  testimony 
of  Dixon  and  Vancouver,  thrust  into  the  soles  of  their  feet, 
sharp  nails  and  pieces  of  glass,  without  feeling  the  slightest  un- 
easiness. On  the  contrary,  the  slightest  prick  from  a thorn,  for 
instance,  in  the  foot,  is  in  the  strongest  African,  frequently 
followed  b\^  convulsions  and  locked  jaw.  The  impression  of  the 
air,  is  alone  sufficient  to  produce  the  same  accident  in  the  negro 
children  in  the  colonies,  the  greater  number  of  whom  die  of 
locked  jaw,  a few  days  after  birth. 

Montesquieu*  very  justly  observed  this  difference  which 
exists  in  the  sensibility  of  the  southern  and  northern  nations 
and  he  says  of  the  latter,  that  “ if  you  would  tickle  you  must 
flay  them.” 

*This  plillosopher  has  borrowed  from  tlie  father  of  pliysic,  one  of  his  most 
brilliant  and  paradoxical  ojilnions.  In  his  conception,  warm  climates  are  the 
seat  of  despotism,  and  the  cold,  the  seal  of  liberty.  This  error  is  completely 
refuted  in  the  profound  and  philosophical  work  of  Volney  on  Egvpt  and  Syria- 
He  shews,  that  what  Montesquieu  has  said  of  cold  climates,  applies  to 
mountainous  regions,  while  a champaign  is  more  favourable  to  the  establish- 
ment of  tyranny.  Hippocrates  had  said  of  the  Asiatics,  that  their  being  less 
■warlike  than  the  Europeans,  depended  on  the  difference  of  climate,  and  like- 
wise on  the  despotic  form  of  their  government.  And  he  observes,  that  men  who 
do  not  enjoy  their  natural  rights,  but  whose  affections  are  controlled  by  mas- 
ters, cannot  feel  the  bold  passion  of  war. 

See  chap.  XI.  on  the  Varieties  of  the  Hum.an  Species. 


33 


Now,  as  the  imagination  is  always  proportioned  to  the  sensi- 
bility, all  the  arts  that  are  cultivated  and  brought  to  perfection, 
only  by  the  exercise  of  that  faculty,  will  flourish  with  difficulty 
near  the  icy  polar  regions,  unless  the  powerful  influence  of 
climate  be  counteracted  by  well  directed  moral  and  physical 
causes. 

Man  is  of  all  beings,  the  one  that  most  powerfully  resists  the 
influence  of  external  causes;  and  although  the  influence  of 
climate  is  sufficient  to  modify  his  external  appearance,  so  as 
to  lead  to  a division  of  the  species  into  several  distinct  varieties 
or  kinds,  this  superficial  impression  is  very  different  from  the 
great  alterations  to  which  other  beings  are  exposed,  from  the 
mere  change  of  climate.  Man  is  every  where  indigenous,  and 
exists  in  all  climates;  while  the  plants  and  animals  of  the 
equator  languish  and  die  when  conveyed  to  the  polar  regions. 
From  the  flexibility  of  his  nature,  man  enjoys  the  power  of 
adapting  himself  to  the  most  opposite  situations,  of  establish- 
ing, between  them  and  himself,  relations  compatible  with  the 
preservation  of  life.  Nevertheless,  it  is  not  without  difficulty 
that  man  undergoes  these  changes,  and  accustoms  himself  to 
new  impressions.  The  periodical  return  of  the  seasons  deter- 
mines that  of  certain  derangements,  to  which  the  animal  eco- 
nomy is  subject.  The  same  diseases  manifest  themselves  under 
the  influence  of  the  same  temperature,  and  to  use  an  ingenious 
comparison,  resemble  those  birds  of  passage  which  visit  us  at 
stated  seasons  of  the  year.  Thus,  hemorrhages  and  eruptive 
affections  come  on  with  the  return  of  the  spring,  summer 
comes  attended  by  bilious  fevers,  autumn  brings  on  a return 
of  dysenteric  affections,  and  winter  abounds  in  inflammation  of 
the  lungs  and  other  parts.  The  influence  of  climate,  on  the 
human  body,  does  not  shew  itself  merely  in  occasioning  epi- 
demic diseases,  the  consideration  of  which  leads  to  the  estab- 
lishing what  physicians  call  medical  constitutions.  This  influence 
operates  on  man  in  health,  as  well  as  in  sickness;  and  to  say 
nothing  of  the  alterations  which  our  moral  nature  experiences 
from  the  tendency  to  love,  rendered  more  impetuous  with  the 
return  of  spring,  or  of  the  melancholy  to  which  nervous  people 
are  often  subject  towards  the  end  of  autumn,  when  the  trees  are 
shedding  their  leaves,  the  increase  of  growth  is  particularly 

£ 


34 


remarkable  at  the  time  of  the  first  growth  of  plants,  as  was 
observed  again  and  again,  by  a friend  of  mine,  physician  to  a 
large  seminary. 

Seventhly.  Sensibility  is  greater  in  women  and  children; 
their  nerves  are  likewise  larger  and  softer,  in  proportion  to 
the  other  parts  of  the  body.  In  general,  the  principle  of  sen- 
sibility seems  to  decrease,  in  proportion  as  it  has  contributed  to 
the  development  of  the  acts  of  life;  and  the  power  of  being  im- 
pressed by  external  objects,  diminishes  gradually  with  age,  so 
that  there  is  a period  of  decrepid  old  age,  at  which  death  appears 
a necessary  consequence  of  the  complete  exhaustion  of  that 
principle.  In  short,  as  I have  said  in  describing  the  progress  of 
death,  at  its  approach,  sensibility  shews  increase  of  activity  and 
liveliness,  as  if  its  quantity  required  to  be  completely  exhausted, 
before  the  termination  of  existence,  or  as  if  the  organs  made  a 
last  effort  to  cling  to  life. 

The  development  of  the  cellular  and  adipose  substance,  di- 
minishes the  energy  of  sensibility;  the  extremities  of  the  nerves 
being  more  covered,  and  therefore  not  so  immediately  applied 
to  the  objects,  the  impressions  which  are  felt,  are  more  obscure. 
The  fat  operates  on  the  nerves,  as  wool  would  do  on  vibrating 
chords,  if  wrapped  round  them,  to  fix  them,  to  prevent  their 
quiverings,  and  stop  their  vibrations. 

Very  nervous  women  are  very  thin;  persons  of  much  sensi- 
bility have  seldom  much  embonpoint.  Swine,  in  which  the  nerves 
are  covered  by  a thick  layer  of  fat,  are  the  most  insensible  of  all 
animals.  The  susceptibility  of  the  nerves  may  be  diminished, 
and  their  sensibility  blunted  by  pressure.  The  application  of  a 
bandage  firmly  rolled  round  the  body  and  limbs  of  an  hysteri- 
cal woman,  will  diminish  the  violence  of  her  fits.  In  dressing 
wounds  affected  with  what  is  called  the  hospital  gangrene,  I 
have  often  relieved  the  pain,  by  desiring  an  assistant  to  apply 
firm  pressure  above  the  sore. 

Eighthly.  There  exists  between  the  force  of  the  muscles,  and 
the  sensibility  of  the  nerves,  between  the  sensible  energy  and 
the  force  of  contraction,  a constant  opposition,  so  that  the  most 
vigorous  athlets,  whose  muscles  are  capable  of  the  most  prodi- 
gious efforts,  and  of  the  most  powerful  contractions,  are  but 
slightly  affected  by  impressions,  and  are  with  difficulty  roused 


35 


into  action,  as  we  have  explained  in*  giving  a history  of  the 
nervous  and  muscular  temperaments,  which  are  characterized 
by  this  difference.  Hence,  man  has  more  sensibility  than  the 
quadrupeds,  although  his  nerves  are  smaller  than  theirs,  which 
seem  destined  to  set  the  muscles  into  action,  and  to  serve  as 
nerves  of  motion,  rather  than  of  sensation. 

There  is  no  muscular  fibre,  however  minute,  in  which  we  are 
not  obliged  to  admit  the  existence  of  a small  nervous  filament, 
to  which  it  probably  owes  the  power  of  contracting;  contractility, 
at  least  voluntary  contractility,  does  not  appear  to  be  inherent 
in  the  muscular  fibre,  nor  independent  of  the  nerves,  through 
the  medium  of  which,  the  will  determines  the  action  of  the 
muscles;  and  if  these  last  organs  when  insulated,  contract  on 
the  direct  application  of  a stimulus,  is  there  not  reason  to  suspect, 
that  this  stimulus  acts  on  that  portion  of  nerves  which  remains 
in  the  muscle,  after  it  has  been  insulated,  and  which  is  inti- 
mately united  to  its  fibres?  The  animals  which  have  no  distinct 
nervous  system,  possess  at  once  in  all  their  parts,  sensibility  and 
contractility;  these  two  properties  become  blended  in  the  organs, 
as  well  as  in  the  phenomena  of  life,  and  can  be  perceived  sepa- 
rate, only  by  a pure  abstraction  of  the  mind,  which  considers  in 
succession  the  impression  produced  on  these  beings,  and  the 
motion  of  their  substance,  which  is  an  immediate  consequence 
of  that  impression. 

We  will  not  enter  any  farther  into  a consideration  of  the  laws 
and  phenomena  of  the  vital  properties,  for  fear  of  being  led  into 
useless  repetitions,  when  we  come  to  the  history  of  the  functions 
over  which  they  preside.  We  will  conclude  what  relates  to 
them,  by  presenting  the  two  most  important  features  of  their 
history,  I mean,  sympathy  and  habit. 

§ VII.  OF  SYMPATHY. 

There  exist  among  all  the  parts  of  the  living  body,  intimata 
relations;  all  correspond  to  each  other,  and  carry  on  a reciprocal 
intercourse  of  sensations  and  affections.  These  links  which  unite 
together  all  the  organs,  by  establishing  a wonderful  concurrence, 
and  a perfect  harmony  among  all  the  actions  that  take  place  in 
the  animal  economy,  are  known  under  the  name  of  sympathies^ 
The  nature  of  this  phenomenon  is  yet  unknown;  we  know  mt 


36 


why,  when  a part  is  irritated,  another  very  distant  part  partakes 
in  that  irritation,  or  even  contracts;  we  do  not  even  understand 
what  are  the  instruments  of  sympathy,  that  is,  what  are  the 
organs  which  connect  two  parts,  in  such  a manner,  that  when 
one  feels  or  acts,  the  other  is  affected.  But  though  beyond 
explanation,  sympathy  is  not  the  less  important  in  the  economy 
of  living  beings;  and  these  connexions  between  remote  parts, 
constitute  one  of  the  most  remarkable  differences  between  those 
beings  and  inorganic  bodies.  Nothing  similaf*  is  observable  in 
dead  or  inanimate  nature,  in  which  all  things  are  connected 
together,  only  by  palpable  and  material  links;  here  the  chain  is 
invisible,  the  connexion  evident,  the  cause  occult,  and  the  effect 
apparent. 

Whytt  has  clearly  shewn,  that  the  nerves  cannot  be  consi- 
dered as  the  exclusive  instruments  of  sympathy,  since  several 
muscles  of  a limb  which  receive  filaments  from  the  same  nerve, 
do  not  sympathize  together,  while  there  may  be  a close  and 
manifest  relation  between  two  parts,  of^  which  the  nerves  have 
no  immediate  connexion,  since  each  nervous  filament  having 
one  of  its  extremities  terminating  in  the  brain,  the  other,  in  the 
part  to  which  it  is  sent,  remains  distinct  from  those  of  the 
same  trunk,  and  does  not  communicate  with  them. 

Sympathies  may  be  distinguished  into  different  kinds.  In  the 
first  place,  two  organs,  which  execute  similar  functions; — the 
kidnies  may  supply  each  other’s  office.  When  the  uterus  is  in  a 
state  of  pregnancy,  the  breasts  participate  in  its  condition,  and 
there  is  determined  into  them  a flow  of  humours  necessary  to 
the  secretion  which  is  to  take  place.  Secondly.  The  continuity 
of  membranes  is  a powerful  source  of  sympathy.  The  presence 
of  worms  in  the  bowels,  determines  an  uneasy  pruritus  around 
the  nostrils.  When  there  is  a stone  in  the  bladder,  a certain  de- 
gree of  itching  is  felt  at  the  extremity  of  the  glans.  The  secre- 
tion of  several  fluids  is  determined  in  the  same  manner;  thus, 
the  presence  of  food  in  the  mouth,  brings  at  the  extremity  of 
the  parotid  duct,  an  irritation  which  extends  to  the  parotid 
glands,  calls  them  into  action,  and  increases  their  secretion. 
Thirdly.  If  the  pituitary  membrane  is  irritated,  the  diaphragm, 
with  which  it  has  no  immediate  organic  connexion,  nervous, 
vascular,  or  membranous,  contracts,  and  occasions  sneezing.  Is 


37 


not  this  sympathy  one  of  those  which  Haller  ascribed  to  a re~ 
action  of  ih&  sensorium  conununeP  If  the  impression  produced 
on  the  olfactory  nerves  by  snuff,  is  too  powerful,  the  uneasy 
sensation  is  transmitted  to  the  brain,  which  determines  towards 
the  diaphragm,  a quantity  of  the  principle  of  motion  sufEcient 
to  enable  that  muscle  suddenly  to  contract  the  dimensions  of  the 
chest,  so  as  to  expel  a column  of  air,  that  may  detach  from  the 
pituitary  membrane,  the  substances  that  are  a cause  of  uneasi- 
ness to  it.  Fourthly.  Does  not  the  principle  of  life  seem  to  con- 
trol at  pleasure,  the  phenomena  of  sympathy?  The  rectum, 
when  irritated  by  the  presence  of  the  excrements,  contracts; 
what  cause  determines  the  accessory  and  simultaneous  action  of 
the  diaphragm  and  abdominal  muscles?  Does  this  connexion 
depend  on  organic  communications?  Why,  then,  is  not  the  sym- 
pathy reciprocal,  and  why  does  not  the  rectum  contract,  when 
the  diaphragm  is  irritated?  Fifthly.  Can  the  repeated  habit  of 
the  same  motions  explain  the  harmony  which  is  observed  in 
the  symmetrical  organs?  Why,  when  our  sight  is  directed  to  an 
object,  placed  laterally,  does  the  rectus  externus  of  the  eye  on 
that  side,  act  at  the  same  time  as  the  rectus  internus  of  the 
other  eye?  The  indispensable  utility  of  this  phenomenon,  in 
keeping  a parallelism  of  the  axis  of  vision,  is  very  obvious,  but 
who  can  assign  the  cause?  Why  are  rotatory  motions,  in  differ- 
ent directions,  performed  with  so  much  difficulty  by  the  arm  and 
leg  of  the  same  side  of  the  body.  Can  it  be  called  a just  idea  of 
the  innumerable  varieties  of  this  phenomenon,  and  of  its  fre- 
quent anomalies,  to  say,  with  Rega,  that  there  are  sympathies 
of  action  or  of  contractility  (consensus  actionum^  sympathies  of 
sensibility  (consensus  passionum.') 

All  these  difficulties  render  it  pardonable  in  Whytt,  to  have 
considered  the  soul  as  the  sole  cause  of  sympathy;  which  was, 
in  fact,  a modest  avowal  of  the  difficulty  of  explaining  the  sub- 
ject. We  are  not  justified  in  considering  sympathy  as  an  ano- 
malous action,  as  an  aberration  of  the  vital  power.  Can  it  be 
said,  that  the  natural  order  of  sensibility  and  irritability  is  in- 
verted, in  the  sympathetic  erection  of  the  clitoris  and  of  the 
nipple,  or  in  the  turgescence  of  the  breast,  determined  by  the 
gravid  state  of  the  uterus? 


58 


It  is  by  means  of  sympathy  that  all  the  organs  concur  in  the 
same  end,  and  yield  each  other  mutual  assistance.  It  affords  us 
the  means  of  explaining,  how  an  affection  at  first  local  or  limited 
in  its  extent,  spreads,  and  extends  to  all  the  systems;  it  is  thus 
that  every  morbid  process  is  carried  on.  The  diseases  termed 
general,  always  originate,  through  the  medium  of  association, 
in  the  insulated  affection  of  an  organ  or  a system  of  organs. 

In  fact,  the  affections  which  appear  to  us  most  complex,  in 
the  number,  the  variety  and  the  dissimilarity  of  their  symptoms, 
consist  of  only  one,  or  of  a small  number  of  primitive  or  es- 
sential elements,  all  the  rest  are  accessory,  and  depend  on 
numerous  sympathies  of  the  affected  organ,  with  the  other 
organs  of  the  animal  economy.  Thus,  if  the  stomach  is  the  seat 
of  irritation,  from  foulness  of  its  contents,  pains  of  all  kinds 
come  on,  but  especially  in  the  head  and  limbs,  with  a burning 
heat,  nausea,  loss  of  appetite,  anxiety,  and  these  symptoms  con- 
stitute a disease  which  appears  to  affect  the  whole  system. 

To  go  on  with  the  same  illustration,  the  stomach,  when  op- 
pressed by  irritating  substances,  contracts  spontaneously  to  get 
rid  of  them.  The  universal  disturbance  which  their  presence 
occasions,  seems  directed  towards  the  same  end,  as  if  the  suffer- 
ing organ  called  upon  all  the  others  to  assist  in  relieving  it. 

These  synergies^  or  aggregate  motions,  tending  to  one  end 
and  arising  out  of  the  laws  of  sympathy,  constitute  the  diseases 
termed  general,  as  well  as  the  greater  part  of  those  which  are 
called  local.  It  is  by  means  of  them,  and  through  these  kinds  of 
organic  insurrections,  if  we  may  be  permitted  to  use  that  expres- 
sion, which  perfectly  expresses  our  meaning,  that  nature  strug- 
gles with  advantage,  and  rids  herself  of  the  morbific  principle, 
or  of  the  cause  of  the  disease;  and  the  art  of  exciting  and  direct- 
ing these  actions,  furnishes  the  materials  of  the  most  important 
doctrines  of  the  practice  of  medicine.  I have  used  the  terms 
excite  and  direct;  for,  it  is  necessary  at  times  to  increase,  at 
others  to  diminish  their  intensity  and  force,  and  on  some  occa- 
sions to  excite  them,  when  nature,  overwhelmed  under  disease, 
is  almost  incapable  of  re-action.  This  last  circumstance  belongs 
to  the  diseases  of  the  most  dangerous  kind,  if  we  include  those 
in  which  the  efforts  of  nature,  though  marked  b)*  a certain  de- 
gree of  energy,  are  without  connexion,  or  consent,  and  frus- 


39 


ttated  by  their  want  of  coherence.  The  character  of  these  affec- 
tions was  first  well  expressed  by  Selle,  who  substituted,  for  the 
term  malignant,  which  used  to  be  applied  to  them  without  any 
precise  meaning,  that  of  ataxic^  which  points  out  very  correct- 
ly, the  want  of  order,  and  the  irregular  succession  of  their 
symptoms.* 

A knowledge  of  sympathies  is  of  the  highest  importance  in 
the  practice  of  medicine.f  When  we  wish  to  avert  an  irritation 
fixed  in  a diseased  organ,  experience  and  observation  prove, 
that  it  is  on  the  organ  which  bears  to  it  the  closest  sympathetic 
connexions,  that  it  is  useful  to  apply  medicines  intended  to  ex- 
cite counter  irritation. 

This  might  perhaps  be  the  fittest  place  to  enquire  into  the 
nature  of  those  concealed  relations  which  draw  men  together, 
and  of  those  aversions  which  prevent  their  union;  to  discover 
the  causes  of  those  secret  impulses  which  lead  two  beings 
towards  each  other,  and  force  them  to  yield  to  an  irresistible 
propensity.  We  might  inquire  into  the  reason  of  antipathy,  and 
in  a word,  establish  the  complete  theory  of  moral  sentiments 
and  affections.  Such  an  undertaking  is  greatly  above  our  strength, 
and  besides,  does  not  absolutely  belong  to  our  subject.  It  would 
require  a considerable  time,  and  whoever  shoula  undertake  it, 
would  be  in  considerable  danger  of  losing  his  way  at  every  step, 
in  the  extensive  field  of  conjectures, 

* Symptomata  nervosa,  nec  inter  se,  neque  causis  manifestis  respondentia,  Ordo 
tert.  atactse,  C.  G.  Selle.  Rudimenta  pyretologiae  methodicse. 

f This  information  may  be  obtained,  by  consulting  the  works  of  the  an- 
cients, and  especially  of  Hippocrates,  who  appears  to  have  felt  all  the  impor- 
tance of  this  subject.  Among  the  moderns.  Van  Helmont,  Baglivi,  Rega, 
Whytt,  Hunter,  Barthez,  and  Bichat,  have  collected  on  this  subject,  a great 
number  of  facts  obtained  from  experiments  on  animals,  and  especially  from 
observations  on  diseases. 

J That  law  of  the  animal  economy  termed  “ sympathy  or  consent  of  parts,” 
is  a very  important  one,  and  has  hitherto  been  too  much  overlooked  in  our 
speculations  as  respects  the  phenomena  of  health  and  disease.  There  are 
indeed,  not  wanting  some,  who  have  affected  scepticism  as  to  the  very 
existence  of  such  a law.  True  it  is  that,  at  present,  we  have  no  very  distinct 
intelligence  relative  to  the  nature  of  the  principle:  but  are  we  on  this  account 
to  question  its  existence?  With  equal  reason  might  we  doubt  of  the  sensibility 
or  irritability  of  the  body.  By  whom  has  the  precise  nature  of  either  of  these 
rfualities  of  vital  matter  been  demonstrated?  Yet  we  are  persuaded  of  their 


40 


§ VIII.  OF  HABIT. 

It  is  easier  to  feel  the  meaning  of  this  term  than  to  define  it. 
Habit,  however,  may  be  said  to  consist  in  the  frequent  repeti- 
tion of  certain  acts,  of  certain  motions,  in  which  the  whole  body 

existence  from  the  phenomena  which  they  exhibit,  and  it  is  by  the  same  de- 
scription of  evidence  that  we  are,  or  ought  to  be,  assured  of  the  existence  of 
sympathy. 

“ Causa  latet,  vis  est  notissima.” 

Of  the  manner  in  which  sympathetic  impressions  are  extended,  as  well  as 
of  the  cause  of  the  more  intimate  consent  which  exists  between  parts,  we  are 
not  accurately  informed.  It  wpuld  seem,  however,  that  in  neither  case  is  it  to 
be  exclusively  referred  to  the  mediation  of  the  nerves,  as  is  commonly  imagin- 
ed. Those  sympathies  which  prevail  among  the  various  viscera  of  the  abdo- 
men, and  between  them  and  the  head,  neck  and  contents  of  the  thorax,  may, 
perhaps,  be  explained  by  the  extensive  anastomoses  of  the  intercostals  with 
almost  all  the  nerves  which  proceed  from  the  spinal  marrow.  But  there  are 
many  other  sympathies,  equally  conspicuous,  between  parts,  the  nerves  of 
which  have  not  the  slightest  connection.  Here  it  appears  that,  either  by  the 
co-oiieration  of  diflerent  organs  in  the  performance  of  a function,  as  in  the 
complex  apparatus  subservient  to  respiration,  or  from  similarity  of  structure, 
parts,  though  detached,  being  prone  to  be  affected  by  the  same  cause,  as  the 
parotid  glan  and  testes  in  the  male,  and  the  same  gland  with  the  mammse  in 
the  female,  the  habit  of  acting  in  unison  is  acquired,  and  sometimes  confirmed. 
This  habit  of  concerted  action  is  called  association,  and  has  been  adopted  as 
a principle  by  Locke,  by  Hartley,  and  by  Darwin  to  account  for  the  connection 
which  is  discernible  in  many  of  the  motions  of  the  body,  as  well  as  in  the 
operations  of  the  mind.  Both  the  sound  and  morbid  states  of  the  system  pre- 
sent numerous  instances  of  these  associated  actions,  some  of  which  are  cort- 
stant  and  uniform,  while  others  are  occasional,  and  anomalous,  produced  as  it 
were  accidentally. 

The  principle  of  sympathy  extends  throughout  the  body,  every  portion  of  it 
being  susceptible  of  associative  actions,  by  which  means  the  different  parts 
are  linked  together  so  as  to  form  one  -whole.  Certains  organs  however,  are  more 
eminently  endowed  with  the  property,  as  the  i.terus,  the  brain,  and  especially 
the  stomach.  This  last  viscus  constitutes  the  chief  medium  of  sympathetic 
connection.  With  it,  the  brain,  the  organs  of  sense,  and  deglutition,  the  whole 
of  the  thoracic  and  abdominal  viscera,  the  parts  of  generation  in  each  sex,  the 
blood-vessels,  the  joints,  the  exterior  surface,  and  in  short  all  the  parts  of  the 
system  however  minute,  maintain  a close  and  intimate  sympathy.  Placed  in 
the  middle,  the  stomach  is  the  centre  of  the  greatest  sphere  of  sympathy. 
But,  besides  this  great  sphere,  there  are  many' subordinate  ones,  which  our 
narrow  limits  will  not  permit  us  particularly  to  designate:  as  for  example, 
the  uterus  with  the  different  portions  of  its  own  system,  the  ovaries,  the  mam. 
mae,  *kc.  &c  It  was  on  account  of  its  vast  dominion  over  the  system,  by  its  mul- 
tiplied sympathies,  that  Van  Helmont  selected  the  stomach  as  the  residence  of 
bis  arclueus,  the  anima  medica,  of  Stahl  and  Nicholls. — Ep. 


41 


|3articipates,  or  only  some  of  its  parts.  The  most  remarkable 
effect  of  habit,  is  to  weaken  after  a time  the  sensibility  of  organs. 
Thus  a catheter  introduced  along  the  urethra,  and  allowed  to 
remain  there,  causes  during  the  first  day  rather  sharp  pain;  on 
the  second  day  it  feels  less  uneasy;  on  the  third  day,  it  is  only 
troublesome,  and  on  the  fourth,  the  patient  scarcely  feels  it. 
The  use  of  snuff  at  first  increases  the  secretion  of  mucus  in  the 
nose,  but  if  continued  a certain  time,  it  ceases  to  affect  the  pitui- 
tary membrane,  and  the  secretion  would  diminish  considerably, 
but  for  the  practice  of  increasing  daily  the  quantity  of  that  acrid 
powder;  the  presence  of  a canula  in  the  nasal  duct,  after  the 
operation  for  fistula  lachrymalis,  increases  at  first  the  mucous 
secretion  of  that  canal;  but  in  proportion  as  it  becomes  accus- 
tomed to  the  extraneous  body,  the  secretion  returns  to  its  natu- 
ral condition. 

It  is  only  by  our  sensations  that  we  are  aware  of  our  existence. 
Life,  to  tirake  use  of  the  figurative  language  of  system,  of  a 
modern  writer,  consists  in  the  action  of  stimuli  on  the  vital 
powers.  {Tota  vita^  quanta  est,  consistit  in  stimulo^  et  vi  vitali. 
Brown.)  Sentient  beings  feel  a continual  necessity  of  renewed 
emotions;  all  their  actions  tend  to  the  obtaining  agreeable  or 
disagreeable  sensations;  for,  in  the  absence  of  other  sensations, 
pain  is  sometimes  attended  with  enjoyment.  Those  who  have 
exhausted  every  kind  of  enjoyment,  and  who  have  had  no  plea- 
sures ungratified,  are  led  to  suicide  from  a weariness  of  life;  who 
can  live,  when  all  power  of  feeling  is  gone? 

The  following  is  the  most  extraordinary  and  remarkable  in- 
stance known,  of  the  manner  in  which  habit  and  a frequent 
repetition  of  the  same  impressions,  wear  out  by  degrees  the 
sensibility  of  organs.  A shepherd,  about  the  age  of  fifteen, 
became  addicted  to  onanism,  and  to  such  a degree,  as  to  prac- 
tise it  seven  or  eight  times  a day.  Emission  became  at  last  so 
difficult,  that  he  would  strive  for  an  hour,  and  then  discharge 
only  a few  drops  of  blood.  At  the  age  of  six  and  twenty,  his 
hand  became  insufficient;  all  he  could  do,  was  to  keep  the  penis 
in  a continual  state  of  priapism.  He  then  bethought  himself  of 
tickling  the  internal  part  of  his  urethra,  by  means  of  a bit  of 
wood  six  inches  long,  and  he  would  spend  in  that  occupation 
several  hours,  while  tending  his  flock  in  the  solitude  of  the 

F 


42 


mountains.  By  a continuance  of  this  titillation  for  sixteen  years, 
the  canal  of  the  urethra  became  hard,  callous,  and  insensible. 
The  piece  of  wood  then  became  as  ineffectual  as  his  hand;  at 
last,  after  much  fruitless  effort,  G.  one  day  in  despair,  drew  from 
his  pocket  a blunt  knife,  and  made  an  incision  into  his  glans, 
along  the  course  of  the  urethra;  this  operation,  which  would 
have  been  painful  to  any  one  else,  was  in  him  attended  with  a 
sensation  of  pleasure,  followed  by  a copious  emission.  He  had 
recourse  to  his  new  discovery,  every  time  his  desires  returned. 
When  after  an  incision  into  the  cavernous  bodies,  the  blood  flow- 
ed profusely,  he  stopped  the  hemorrhage,  by  applying  around 
the  penis  a pretty  tight  ligature.  At  last,  after  repeating  the 
same  process  perhaps  a thousand  times,  he  ended  in  splitting 
his  penis  into  two  equal  parts,  from  the  meatus  urinarius  to  the 
scrotum,  very  near  to  the  symphysis  pubis.  When  he  had  got 
so  far,  unable  to  carry  his  incision  any  farther,  and  again  re- 
duced to  new  privations,  he  had  recourse  to  a piece  of  wood, 
shorter  than  the  former:  he  introduced  it  into  what  remained  of 
the  urethra,  and  exciting  at  pleasure  the  extremities  of  the 
ejaculatory  ducts,  he  provoked  easily  the  discharge  of  semen. 
He  continued  this  about  ten  years;  after  that  long  space  of  time, 
he  one  day  introduced  his  bit  of  wood  so  carelessly,  that  it  slip- 
ped from  his  fingers  and  dropped  into  the  bladder.  Excruciating 
pain  and  serious  symptoms  came  on.  The  patient  was  conveyed 
to  the  Hospital  at  Narbonne.  The  surgeon,  surprized  at  the 
sight  of  two  penes  of  ordinary  size,  both  capable  of  erection, 
and  in  that  state  diverging  on  both  sides,  and  seeing  besides 
from  the  scars  and  from  the  callous  edges  of  the  division,  that 
this  conformation  was  not  congenital,  obliged  the  patient  to 
give  him  an  account  of  his  life,  which  he  did,  with  the  details 
which  have  been  related.  This  wretch  was  cut  as  for  the  stone, 
recovered  of  the  operation,  but  died  three  months  after,  of  an 
abscess  in  the  right  side  of  the  chest,  his  phthisical  state  having 
been  evidently  brought  on  by4he  practice  of  onanism  carried  on 
nearly  forty  years.* 

The  habit  of  suffering,  renders  us  in  the  end  insensible  to 
pain;  but  every  thing  in  this  world  is  balanced,  and  if  habit 

• Ghopart,  maladies  des  voles  urinaires.  Tome  II. 


43 


lightens  our  evils,  by  blunting  sensibility,  it  on  the  other  hand 
drains  the  source  of  our  sweetest  enjoyments.  Pleasure  and 
pain,  these  two  extremes  of  sensation,  in  a manner,  approximate 
to  each  other,  and  become  indifferent  to  him  who  is  accustomed 
to  them.  Hence  arises  inconstancy,  or  rather  that  insatiable  de- 
sire of  varying  the  objects  of  our  inclinations,  that  imperious 
want  of  new  emotions;  hence  we  possess  with  indifference  what 
we  pursued  with  tlje  utmost  ardour  and  perseverance,  and  even 
cease  to  be  impressed  by  those  charms  which  once  held  us 
captivated. 

A striking  instance  of  the  powerful  influence  of  habit  on  the 
action  of  organs,  is  afforded  by  that  criminal  who,  we  are  told 
by  Sanctorius,  was  taken  ill  on  being  removed  from  a noisome 
dungeon,  and  did  not  recover  till  he  was  replaced  in  the  impure 
air  to  which  he  had  been  long  accustomed.  Mithridates,  that  for- 
midable rival  of  the  Roman  power,  dreading  to  be  taken  alive 
by  his  enemies,  tried  in  vain  to  put  an  end  to  his  life,  by  taking 
large  doses  of  the  most  subtle  poisons,  because  he  had  long 
inured  himself  to  their  action.*  It  has,  therefore,  been  justly 
said  of  habit,  that  it  is  a second  nature,  whose  laws  ought  to  be 
respected. 

The  organs  of  generation  in  women,  in  consequence  of  their 
lively  sensibility,  are  in  an  especial  manner  submitted  to  the 
powerful  influence  of  habit.  The  womb,  after  a miscarriage,  has 
a tendency  to  a renewal  of  the  same  occurrence,  when  the  same 
period  of  pregnancy  recurs,  so  that  the  greatest  precautions  are 
necessary  to  prevent  abortion  in  women,  who  are  subject  to 
it,  when  they  have  reached  the  month  in  which  they  before  mis- 
carried. 

May  not  death  be  considered  as  a natural  consequence  of  the 
laws  of  sensibility?  Life,  depending  on  the  continual  excitement 
of  the  living  solids  by  the  fluids  which  moisten  them,  ceases, 
because  the  parts  endowed  with  sensibility  and  contractility, 
after  long  habitude  of  the  impressions  of  those  fluids,  lose  their 
capacity  of  feeling  them.  Their  action  gradually  extinguished, 

* In  some  very  rare  cases,  habit  produces  a quite  contrary  effect.  Cullen 
slates,  that  he  knew  persons  so  accustomed  to  excite  vomiting  in  themselves, 
that  the  twentieth  part  of  a grain  of  tartar  emetic  was  sufficient  to  excite  a 
eonvulsive  action  of  the  stomach. 


44 


would  perhaps  revive,  if  the  energy  of  the  stimulating  power 
were  increased. 

A knowledge  of  the  power  of  habit,  is  a useful  guide  in  the 
application  of  remedies,  the  greatest  part  of  which  operate  in 
the  cure  of  diseases,  only  by  modifying  sensibility.  A wound  in 
which  lint  has  kept  up  the  degree  of  inflammation  necessary  to 
cicatrization,  becomes  insensible  to  that  application,  the  parts 
become  spungy  and  soft,  and  the  cure  is  protracted.  The  lint 
should  then  be  covered  with  an  irritating  powder,  and  the 
pledgets  soaked  in  an  active  fluid:  one  may  safely  increase  the 
doses  of  a medicine  which  has  been  long  employed.  Thus,  in  the 
treatment  of  the  venereal  disease  by  mercurials,  the  dose  is  to 
be  gradually  increased;  with  the  same  view,  Frederic  HoflFman 
recommended  in  the  treatment  of  chronic  diseases,  that  the  re- 
medies should  be  suspended  for  a time  and  then  resumed,  lest 
the  system  should  get  accustomed  to  them  and  their  influence 
be  lost.  The  same  motive  should  lead  one  to  vary  the  treatment, 
and  to  employ  in  succession,  th(/se  medicines  to  which  nearly 
the  same  qualities  are  assigned,  for,  each  of  them  calls  forth  the 
sensibility  in  a peculiar  manner.  The  nervous  system  may  be 
compared  to  an  earth  abounding  in  various  juices,  and  for  a full 
display  of  whose  fecundity,  it  is  necessary  that  the  husbandman 
commit  to  it  the  germs  of  various  plants. 

It  is  very  remarkable  that  habit,  or  the  frequent  repetition  of 
the  same  act,  which  uniformly,  under  all  circumstances,  and  in 
all  organs,  blunts  physical  sensibility,  should  improve  the  intel- 
lect, and  increase  the  facility,  and  activity  of  execution  of  all 
the  operations  of  the  understanding,  or  of  the  actions  which  de- 
pend on  them.  “ Habit  impairs  the  sensitive power^  and  im- 
proves the  judgment,’’'  Bichat  was  therefore  incorrect,  when  m 
his  distinction  of  the  organs  which  are  subservient  to  the  func- 
tions of  assimilation,  from  those  which  serve  to  keep  up  our 
relation  with  the  surrounding  objects,  he  maintained  that  the 
sensibility  of  the  latter  becomes  more  exquisite,  while  the  sen- 
sibility of  the  former  becomes  impaired  from  habit. 

But  can  a painter,  because  he  judges  more  correctly  than  the 
ignorant  of  the  beauties  of  a picture,  be  said  to  see  it  better? 
Surely  not,  for,  he  may  with  a sight  far  less  penetrating,  and 
more  infirm,  form  a more  accurate  analysis,  from  the  habit 
which  he  has  acquired,  and  judge  with  a great  deal  more 


45 


prompitude  and  certainty,  of  the  several  parts  and  of  the  wholes 
just  as  the  practised  ear  of  the  musician  seizes,  in  a piece  of 
music,  and  during  the  most  rapid  execution,  the  expression  and 
the  value  of  all  the  notes  and  tones.  The  error  has  arisen,  from 
its  being  forgotten,  that,  correctly  speaking,  it  is  not  the  eyes 
that  see,  or  the  ears  that  hear;  that  the  impressions  produced  by 
the  sounds  on  these  organs,  are  but  the  occasional  cause  of  the 
sensation,  or  of  the  perception  of  which  the  brain  is  the  exclu- 
sive seat.  Which  has  the  more  delicate  sense  of  hearing,  the 
North  American  savage,  who  hears  the  noise  of  the  step  of  his 
enemies,  at  distances  that  astonish  us,  or  the  artist  who  does  not 
hear  a person  speaking  at  the  distance  of  fifty  paces  from  him, 
but  who  directs  with  judgment,  all  the  operations  of  a great  or- 
chestra, and  who  distinguishes  skilfully,  the  effect  of  each  part? 

Bring  down  to  a frugal  Pythagorean  regimen,  one  of  our 
modern  epicures:  his  palate,  exhausted  of  its  sensibility  by  the 
most  savoury  dishes,  by  ardent  liquors  and  the  most  exquisite 
ragouts,  will  discover  no  taste  in  dry  bread.  Let  him,  however, 
live  on  bread,  if  he  can,  for  some  time,  it  will  soon  appear  to 
him  to  have  a grateful  taste,  as  it  does  to  those  who  make  it 
their  principal  article  of  food,  or  who  take  it  only  with  sub- 
stances which  have  not  a very  distinct  taste.  Although  with  the 
sense  of  smell,  that  of  taste  furnishes  us  only  with  ideas  the 
most  directly  connected  with  our  preservation,  those  which 
most  turn  upon  the  wants  of  our  animal  nature:  although  we 
retain,  with  difficulty,  the  impressions  of  these  senses,  and  that, 
to  enable  us  to  retain  them,  they  must  be  often  repeated;  the 
epicure  had  so  carefully  analysed  them,  that  he  had  attained  to 
the  discernment  of  the  faintest  differences  of  taste,  all  those 
delicacies  of  sensation,  which,  as  Montesquieu  said,  are  lost  to 
us  vulgar  eaters. 

The  motions,  under  the  direction  of  the  will,  acquire  by  the 
precision  of  the  determinations,  the  same  aptness,  facility,  and 
readiness;  and  the  dancer,  who  surprises  us  with  his  agility,  has 
reflected,  more  than  might  be  imagined,  on  the  very  complicated 
steps  of  which  a ballet  is  composed. 

Morbid  sensibility,  is  equally  under  the  influence  of  habit.  I 
have  always  observed,  that  discharges  from  the  urethra  become 
less  painful  from  their  frequency.  There  is  nothing  down  to 


46 


disease  Itself,  that  is  not  made  lighter  by  habit,  as  has  been  well 
observed  by  the  old  man  of  Cos. 

It  remains  then  demonstrated,  even  as  a general  thesis,  that 
habit  or  the  frequent  repetition  of  the  same  acts,  while  it  regu- 
larly reduces  physical  sensibility,  improves  intelligence,  and 
gives  facility  and  promptness  to  all  the  motions  that  are  under 
the  direction  of  the  will. 

§ IX.  OF  THE  VITAL  PRINCIPLE. 

The  words  vital  principle^  vital  force^  &c.  do  not  express  a 
being  existing  by  itself,  and  independently  of  the  actions  by 
which  it  is  manifested:  it  must  be  used  only  as  an  abridged 
formula,  which  serves  to  mark  the  total  of  the  powers  that  ani- 
mate living  bodies,  and  distinguishes  them  from  inert  matter. 
So  that,  whenever,  in  the  course  of  this  section,  I shall  use  these 
terms,  or  any  equivalent,  it  is  to  be  taken  as  if  I had  said,  the 
aggregate  of  the  properties  and  laws  that  regulate  the  animal 
economy.  This  explanation  is  become  indispensable,  now  that 
several  writers,  realizing  a mere  abstraction,  have  spoken  of  the 
vital  principle,  as  of  something  very  distinct  from  the  body,  as 
of  a being  altogether  separable,  which  they  have  invested  with 
feeling,  and  thought,  and  even  deliberate  intentions. 

From  the  farthest  antiquity,  the  many  and  striking  differences 
of  living,  and  inorganic  bodies,  have  led  some  philosophers  to 
conceive  in  the  former,  a principle,  of  particular  actions,  a force 
which  maintains  the  harmony  of  their  functions,  and  directs 
them  all  to  a common  end,  the  preservation  of  individuals  and 
of  the  species.  This  simple  and  luminous  doctrine  has  remained, 
even  to  our  own  days,  only  modified  in  its  passage  through 
many  years:  and,  no  one  now  disputes  the  existence  of  a prin- 
ciple of  life,  which  subjects  the  beings  that  enjoy  it,  to  a system 
of  laws  different  from  those  which  inanimate  beings  obey;  a 
force,  which  might  be  characterized,  as  withdrawing  the  bodies 
it  animates,  from  the  absolute  dominion  of  chemical  affinities, 
which  would  else,  from  the  multiplicity  of  their  elements,  act 
on  them  with  great  power;  and,  as  maintaining  them  in  a nearly 
equal  temperature,  whatever  may  be  that  of  the  atmosphere. 
Its  essence  is  not  in  preserving  the  aggregation  of  constituent 
molecules,  but  in  drawing  to  it  other  molecules,  which  by  as- 


47 


similation  to  the  organs  it  pervades,  replace  those  that  are  car- 
ried ofF  in  daily  waste,  and  serve  for  their  nourishment  and 
growth. , 

All  the  phenomena  that  are  to  be  observed  in  the  living  hu- 
man body,  might  be  brought  as  proofs  of  the  principle  which 
animates  it. — The  actions  of  the  digestive  organs  on  its  food; 
the  absorption,  by  the  chylous  vessels,  of  its  nutritious  parts; 
the  circulation  of  these  nutritious  juices  through  the  sangui- 
neous system;  the  changes  they  undergo  in  their  passage 
through  the  lungs,  and  the  secretory  glands;  the  impressibility 
by  outward  objects;  the  power  of  approaching  or  avoiding  them; 
in  a word,  all  the  functions  that  are  carried  on  throughout  the 
animal  economy,  proclaim  its  existence.  But  it  is  customary  to 
take  a proof  of  it  yet  more  direct,  from  the  properties  with 
which  the  organs  of  these  functions  are  endowed.  We  have  ex- 
amined these  properties,  and  we  have  seen  that  each  of  them 
presents  us  with,  at  least,  two  great  modifications;  that  the  last 
discovers  three,  which  are,  voluntary  contractility,  contractility 
involuntary  and  insensible,  Stahl’s  tonic  motion;  and  lastly,  con- 
tractility involuntary  and  sensible,  as  that  of  the  heart  and  the 
intestines. 

If  it  is  useful  to  analyse,  in  order  to  know,  it  is  of  equal  im- 
portance not  to  multiply  causes,  from  misconceiving  the  nature 
of  effects.  And  if,  on  the  one  hand,  the  multitude  of  the  pheno- 
mena of  life,  inclines  us  to  the  belief  of  many  causes  to  produce 
them;  the  unfailing  harmony  that  pervades  all  the  actions,  their 
mutual  connexions,  and  reciprocal  dependencies,  point  much 
more  decisively  to  a sole  agent,  as  causing,  directing,  and  con- 
trolling these  phenomena. 

The  hypothesis  of  the  vital  principle,  is  to  the  philosophy  of 
living  beings,  what  attraction  is  to  astronomy.  To  calculate  the 
rev'olutions  of  the  planets,  this  science  is  compelled  to  recognize 
a force,  which  draws  them  constantly  towards  the  sun,  and  con- 
strains their  tendency  to  fly  from  it,  within  the  measured  dis- 
tance of  those  ellipses,  which  they  describe  around  that  common 
centre  of  light  and  heat,  which  dispenses  to  them,  as  they  roll^ 
the  precious  germs  of  life  and  of  fertility.  We  are  about  to  speak 
of  this  force,  to  which  all  the  powers  that  animate  each  separate 
organ,  join  themselves,  and  in  which  all  the  vital  powers  are 


48 


blended,  but  under  the  declaration,  for  the  second  time,  of  using 
the  term  only  in  a metaphorical  sense.  Without  this  precaution, 
I might  lead  you  into  all  the  false  reasonings,  which  those  have 
fallen  into,  who  have  assigned  to  it  a real  and  separate  existence. 

The  vital  power  is  in  perpetual  strife  with  the  powers  that 
govern  inanimate  bodies.  The  laws  of  individual  nature  are,  ac- 
cording to  the  saying  of  antiquit)^,  for  ever  struggling  against 
those  of  universal  nature:  and  life,  which  is  only  this  contest  pro- 
longed, in  favour,  altogether,  of  the  vital  powers,  during  health, 
but  with  uncertain  issue  in  disease,  is  at  an  end,  the  moment  in 
which  the  bodies  endowed  with  it,  fall  again  into  the  system  of 
lifeless  being.  This  constant  opposition  of  vital  to  physical  laws, 
both  mechanical  and  chemical,  does  not  withdraw,  altogether, 
living  bodies  from  the  control  of  these  laws.  There  are  effects 
always  going  on  in  the  living  being,  chemical,  physical,  and  me- 
chanical: only  these  effects  are  constantly  influenced,  modified, 
and  altered  by  the  powers  of  life. 

Why,  when  we  stand  up,  are  not  all  the  humours  carried  down 
to  the  lower  parts,  by  the  force  of  gravitation?  The  vital  power 
resists  the  completion  of  this  hydrostatic  phenomenon,  and  neu- 
tralizes this  tendency  of  the  fluids,  the  more  successfully  as  the 
individual  is  more  robust  and  vigorous.  If  it  is  one  enfeebled 
by  previous  disease,  the  propensitv  will  be  but  imperfectly  re- 
pressed: the  feet,  after  a certain  time,  swell:  and  this  oedematous 
swelling,  can  be  ascribed  only  to  the  insufficient  energy  of  the 
vital  powers,  which  determine  the  distribution  of  the  fluids,  &c. 

When  a tumbler  throws  himself  backwards,  the  blood  does 
not  flow  altogether  to  his  head,  though  this  is  become  the  lowest 
part;  yet  the  natural  tendency  of  fluids  downwards  is  not  alto- 
gether overcome;  it  is  only  diminished;  for  if  he  preserves  long 
the  same  attitude,  the  struggle  of  the  hydraulic  and  vital  powers 
becomes  unequal;  the  former  prevail;  they  accumulate  the  blood 
upon  the  brain  and  the  man  dies. 

The  following  experiment  proves  incontestably,  what  has  just 
been  said  of  the  power  of  resistance,  which,  in  the  human  body, 
more  or  less,  effectually  counterbalances  the  force  of  physical 
laws.  I applied  bags  filled  with  very  hot  sand,  along  the  leg  and 
foot  of  a man  whose  artery  had  been  tied  by  two  ligatures,  in 
the  hollow  of  the  ham,  for  popliteal  aneurism.  Not  only  the 


49 


limb  was  not  chilled,  which  is  what  happens  when  the  course  of 
the  blood  is  intercepted,  but  the  extremity  thus  covered,  ac- 
quired a heat  much  above  the  ordinar)  terhpcrature  of  the  body<> 
The  same  apparatus  applied  to  the  sound  leg,  did  not  produce 
this  excess  of  heat,  certainly,  because  the  fulness  of  life,  in  that 
limb,  resisted  the  physical  action. 

The  vital  principle  seems  to  act  with  the  greater  energy,  as 
the  sphere  of  its  activity  is  narrowed;  which  has  led  Pliny  to 
say,  that  it  was  chiefly  in  the  smallest  things  that  Nature  has 
shown  the  fulness  of  her  ower.'^ 

The  circulation  is  quicker,  the  pulse  more  frequent,  the  deter- 
rainati.  -ns  more  prompt,  in  men  of  short  stature.  Such  was  the 
great  Alexander:  never  did  man  of  colossal  make,  display  great 
activit)'  of  imagination:  none  of  them  have  glowed  with  the  fire 
of  genius.  Slov.'  in  their  actions,  moderate  in  their  desires,  they 
obey,  without  murmuring,  the  will  that  governs  them,  and  seem 
made  for  slavery.  Agrippa  (savs  Omilius  Probus,  in  his  History 
of  Augustus)  advised  that  they  should  disband  the  Spanish 
guard,  and  that  in  its  room,  Csesar  should  choose  one  of  German, 
“ wotting  well,  that  in  these  large  bodies,  there  was  little  of 
“ coverte  malice,  and  yet  lesse  of  subtiltie,  and  that  it  was  a 
“ people  more  minded  to  be  ruled  than  to  rule.” 

To  judge  soundly  of  the  remarkable  difference  which  in- 
equality of  stature  brings  into  the  character,  compare  extremes; 
set  against  a Colossus,  a little  man  of  diminutive  stature;  grant- 
ing, nevertheless,  to  this  last,  full  and  vigorous  health.  You  may 
guess  that  he  is  talkative,  stirring,  always  in  action,  always 
changing  his  place:  one  would  say  that  he  is  labouring  to  recover 
in  time,  what  he  has  lost  in  space.  The  probable  reason  of  this 
difference  in  the  vital  activity,  following  the  difference  of  stature, 
arises  from  the  relative  bulk  of  the  primary  organs  of  life.  The 
heart,  the  viscera  of  digestion,  &c.  are  of  nearly  the  same  bulk 
in  all  men:  in  all,  the  great  cavities  are  nearly  of  the  same  ex- 
tent, and  it  is  principally  in  the  length  of  the  lower  limbs,  that 
the  difference  of  stature  will  be  found  to  lie.  It  is  easily  con- 
ceivable, that  the  viscera  supplying  the  same  quantity  of  nutri- 
tious juices  to  a smaller  bulk,  that  the  heart  giving  the  same 


* ifusquann  magis  qiidm  in  minimis  est  tota  JVatura.  Hist.  Nat.  lib.  II.  cap.  2. 

G 


50 


impulse  to  blood  which  is  to  traverse  a shorter  course,  all  the 
functions  will  be  executed  with  greater  rapidity  and  energy. 

By  an  obvious  consequence,  the  diseases  of  little  men,  have 
a more  acute  character;  they  are  more  vehement,  and  tend  more 
rapidly  to  their  crisis.  They  have  in  them  something  of  the  ve- 
locity, I would  even  say  the  instability  of  morbid  re-action  dur- 
ing infancy.  There  is  nothing  even  to  the  duration  of  life,  on 
which  the  differences  of  stature  have  not  some  influence.  With- 
this  suspicion,  and  some  curiosity  to  ascertain  its  justness,  I 
have  made  enquiries  in  the  hospitals,  where  people  in  advanced 
life  are  taken  in,  and  I found  them,  for  the  most  part,  occupied 
by  old  men  above  the  middle  size;  so  that  reasoning  and  obser- 
vation concur  in  showing  that,  all  things  else  being  equal,  those 
of  superior  stature  have  a grounded  hope  of  prolonging  their 
life  beyond  the  ordinary  term. 

I have  observed,  with  many  others,  that  the  whole  bodv  un- 
failingly receives  an  increase  of  vigour,  from  the  amputation  of 
a limb.  Frequently,  after  the  loss  of  a part  of  the  body,  you  will 
see  a manifest  change  take  place  in  the  temperament;  those  that 
were  weak,  even  before  the  disease  which  brings  on  the  neces- 
sity of  the  operation,  becoming  robust;  affections,  chronic  from 
debility,  such  as  scrophula,  tabes  mesenterica,  dissipated;  glan- 
dular swellings  resolved;  which  indicates  a very  remarkable  in- 
crease in  the  actions  of  all  the  organs.* 

The  parts  most  remote  from  the  centre  of  circulation  are,  in 
general,  less  alive  than  those  which  are  nearer.  Wounds  of  the 
legs  and  feet,  are  more  liable  to  ulcerate,  because,  besides  the 

* The  extraordinary  de%'elopment  of  an  organ,  never  takes  place  but  at  the 
expense  of  those  about  it,  of  which  it  draws  off  the  juices.  Aristotle  observes, 
that  the  lower  extremities  are  almost  always  dry,  and  wa.sted  in  those  who  are 
of  ardent  temperament,  or  in  habits  of  frequent  venery.  Hippocrates  relates 'm 
his  work  ( De  aere,  loch,  et  aguh,  Foes:  fol.  293.)  that  the  Scythian  women  seared 
their  right  breast,  that  the  arm  on  that  side  might  grow  in  size  and  strength. 
Galen  speaks  of  Athletes,  who,  in  his  time,  kept  the  sexual  organs  in  the  most 
entire  inaction,  that  withered,  shrunk,  and  perished,  in  some  sort,  by  this  ab- 
solute repose,  they  might  not  draw  ofl'the  nutritious  juices  from  the  sole  nou- 
rishment of  the  muscular  organs.  A young  man,  who  has  several  times  carried 
off  the  prize  by  running  at  the  public  fetes,  abstains  from  venerj-  for  some 
months,  before  entering  the  lists,  in  perfect  certainty  of  victory,  after  this  pri- 
vation. 


51 


circulation  of  the  fluids,  which  the  slightest  weakness  greatly  re- 
tards in  them,  their  life  is  too  feeble  for  their  wounds  to  go 
quickly  through  their  periods,  and  readily  cicatrize.  The  toes 
freeze  first,  when  we  remain  too  long  exposed  to  severe  cold: 
it  is  in  them  too  that  the  mortification  begins,  which  sometimes 
attacks  a limb  after  the  ligature  of  its  vessels. 

Thus,  although  we  may  say,  that  the  principle  of  life  is  not 
seated  in  any  part  of  our  being,  that  it  animates  every  system  of 
organs,  every  separate  organ,  every  living  molecule,  that  it  en- 
dows them  with  different  properties,  and  assigns  to  them,  in  some 
sort,  specific  characters,  it  must  be  confessed,  that  there  are  in  the 
living  body  some  parts  more  alive,  from  which  all  the  others  seem 
to  derive  motion  and  life.  We  have  already  seen,  that  these  cen- 
tral organs,  these  foci  of  vitally,  in  whose  life  that  of  the  whole 
body  is  involved,  diminish  gradually  in  number  in  the  animal 
kinds,  as  they  are  more  removed  from  man,  whilst  the  fewer  they 
are,  the  more  they  are  spread  out  over  the  body;  so  that  life  is 
more  generally  diffused,  and  its  phenomena  less  rigorously  and 
strictly  connected,  as  we  descend  in  the  scale  of  being,  from  the 
red  and  warm-blooded,  to  the  red  and  cold-blooded  animals, from 
these  to  the  mollusca,  the  Crustacea,  worms  and  insects,  to  the  po- 
lypus, who  forms  the  extreme  link  of  the  animal  chain,  and  lastly, 
to  plants,  of  which  not  a few,  like  the  zoophytes,  so  similar  to 
them  in  many  respects,  are  endowed  with  the  remarkable  pro- 
perty of  reproduction  by  slips;  which  implies,  that  each  part  con- 
tains the  aggregate  of  organs  necessary  to  life,  and  can  exist  alone. 

The  vital  principle  has  by  some  been  confounded  with  the 
rational  soul;  but  others  have  distinguished  it  from  the  emana- 
tion of  divinity,  to  which  as  much  as  to  the  perfection  of  his 
organization,  man  owes  his  superiority  to  all  the  animal  kinds. 
What  bond  unites  the  material  principle,  which  receives  impres- 
sions and  transmits  them,  to  the  intelligence  which  feels,  per- 
ceives, examines,  compares,  judges,  and  reasons  on  them?  Were 
man  one,  says  Hippocrates,  did  his  material  principle  make  up 
his  whole  nature,  pleasure  and  pain  would  be  as  nothing  to  him; 
he  would  be  without  sensation:  for,  how  could  he  account  to 
himself  for  impressions?  5’i  unus  esset  homo^non  doleret^  quia 
non  sciret  unde  doleret.  Here  we  stand  on  the  confines  of  phy- 
siology and  metaphysics:  let  us  beware  of  setting  foot  in  the 


52 


dim  paths  that  are  before  us:  the  torch  of  observation  would 
yield  but  ineffectual  light,  too  faint  to  dispel  the  thick  darkness 
that  lies  over  them. 

The  vital  power  is  merely  the  vis  medicatrix  naturte,  more 
powerful  than  the  physician,  in  the  cure  of  many  diseases;  the 
art  of  the  physician  consisting,  in  most  cases,  in  atvakeninc:  or 
directing  the  action  of  that  power.  When  a thorn  is  thrust  into 
a part  endowed  with  sensibiliiv,  a sharp  pain  is  felt,  the  fluids 
rush  in  abundance  to  the  part,  it  becomes  red  and  swollen;  all 
the  vital  powers  are  excited,  the  sensibility  becomes  more  acute, 
the  contractility  greater,  and  the  temperature  rises.  Does  not 
this  increase  of  vital  energy  in  the  injured  part,  this  process 
which  takes  place,  around  the  substance  that  is  the  cause  of  the 
disorder,  those  means  w'hich  are  provided  to  expel  it,  indicate 
the  existence  of  a preserving  principle,  incessantly  watching 
over  the  harmony  of  the  functions,  and  struggling  against  all 
the  powers  that  may  tend  to  interrupt  its  exercise,  or  to  annihi- 
late the  vital  motion? 

Theory  of  injlammation.  Inflammation  may,  I believe,  be  de- 
fined, the  increase  of  vital  properties  in  the  part  which  it  affects. 
Sensibility  becomes  more  acute  in  the  part  so  affected,  its  con- 
tractility greater;  and  from  that  increase  of  sensibility , and  ac- 
tion, arise  all  the  symptoms  characteristic  of  inflammation.  Thus 
the  pain,  the  swelling,  the  redness,  the  heat,  and  the  difference 
in  the  state  of  the  secretions,  denote  in  the  part,  a more  ener- 
getic and  active  vitality. 

I'hose  who  have  objected  to  the  definition  which  I have  given 
of  inflammation,  have  evidently  mistaken  the  functions  of  the 
organs  for  their  properties.  It  is  very  true,  that  inflammation 
of  the  eye  is  attended  with  loss  of  sight,  but  that  circumstance 
depends  on  the  opacity  of  the  transparent  parts  which  should 
transmit  the  luminous  rays  of  the  retina.  The  sight  is  prevented 
by  a mechanical  obstacle,  but  the  sensibility  of  the  organ  is  aug- 
mented, to  such  a degree,  that  the  faintest  light  reaching  the 
bottom  of  the  eye,  through  the  transparent  cornea  dimmed  by 
the  congestion  of  the  vessels,  causes  in  it  intolerable  pain.  On 
this  principle,  darkness  is  universally  recommended  to  patients 
affected  with  ophthalmia.  In  like  manner,  when  a muscle  is  in- 


S3 


flamed,  the  action  of  the  fibre,  its  decurtatlon,  is  prevented  by 
the  congestion  in  the  cellular  membrane,  which  covers  it,  and 
fills  its  interstices.  The  cause  preventing  contraction,  or  the 
exercise  of  contractility,  is  mechanical,  and  may  be  compared 
to  that,  which,  in  an  inflamed  lung,  opposes  the  admission  of  air? 
and  the  passage  of  the  blood,  from  the  right  to  the  left  side  of 
the  heart.  Can  any  one  call  in  question,  the  increase  of  vital  ac- 
tion in  peripneumony?  I am  therefore  of  opinion,  that  the  above 
definition  is  better  than  that  proposed  by  Bichat,  in  his  “ Ana- 
tomie  generale,”  a work  of  later  date  than  the  first  edition  of 
these  Elements  of  Physiology,  and  in  which  he  makes  inflam- 
mation to  consist  in  the  increase  of  those  l ital  properties,  which 
he  terms  insensible. 

All  the  parts  of  the  human  body,  with  the  exception  of  the 
epidermis  and  its  different  productions,  as  the  nails  and  the  hair, 
appear  capable  of  inflammation.  One  might  include  among  these 
“ epidermoid”  parts,  certain  dry  and  slender  tendons,  as  those  of 
the  flexors  of  the  fingers,  which  when  pricked,  lacerated  and  ir- 
ritated in  a thousand  ways,  are  insensible  to  pain,  and  remain 
uninjured  in  the  midst  of  a whitlow,  though  attended  with  sup- 
puration of  all  the  neighbouring  soft  parts;  and  when  exposed  to 
the  air,  they  exfoliate  instead  of  granulating.  Organization  is  so 
indistinct  in  all  these  parts,  life  so  feeble  and  languid,  that  they 
remain  insensible  to  the  impression  of  all  those  causes  which 
might  tend  to  increase  its  activity. 

The  degree  of  sensibility  in  a part,  the  number  and  size  of  the 
nerves  and  vessels  which  are  sent  into  it,  determine  the  degree 
of  its  aptitude  to  inflammation;  thus  the  bones  and  cartilages  in- 
flame with  considerable  difficulty.  When  one  of  these  parts  is 
laid  bare,  the  first  effect  of  the  irritation  to  which  it  is  exposed,  is 
a softening  of  its  substance.  When  a bone  is  laid  hare,  it  becomes 
cartilaginous  and  softens,  in  consequence  of  the  absorption  of  the 
phosphate  of  lime  which  fills  up  the  interstices  of  its  tissue;  and 
it  is  only  after  this  kind  of  incarnation,  that  fleshy  granulations 
begin  to  sprout,  as  may  be  observed  on  the  extremities  of  bones 
after  amputation.  The  difficulty  with  which  inflammation  is  set 
up  in  the  harder  parts  of  the  body,  explains  why,  before  the  twelfth 
or  fifteenth  day  after  a fracture,  it  is  of  little  consequence  towards 
union  of  the  bone,  that  the  fractured  ends  should  be  placed  in 


54 


apposition}  not  that  is  it  right  to  wait  so  long,  before  applying 
the  proper  bandages,  which  are  indispensable  from  the  first,  to 
prevent  the  pain  and  laceration  occasioned  by  the  displaced 
bones.  The  blood  is  determined,  from  all  quarters,  towards  the 
irntated  and  painful  part,  which  swells  and  assumes  a red  colour, 
from  the  presence  of  that  fluid.  The  swelling  would  be  unlimited, 
if,  at  the  same  time  that  the  arteries  increase  in  power  and  cali- 
ber, to  occasion  that  determination,  the  veins  and  lymphatics  did 
not  acquire  a corresponding  energy,  to  enable  them  to  relieve 
the  part  of  the  fluids  which  have  accumulated  in  it,  and  which 
irritation  is  constantly  determining  to  it.  The  power  of  irrita- 
bility and  contractility  increases  with  sensibility;  the  circulation 
is  more  rapid,  in  the  inflamed  part;  the  pulsations  of  the  capil- 
lary vessels  are  manifest.  The  part  is  likewise  hotter,  because, 
in  a given  time,  there  passes  through  its  tissue  more  arterial 
blood,  from  which  a larger  quantity  of  caloric  is  disengaged, 
and  the  continued  effects  of  the  pulmonary  respiration  are  bet- 
ter marked  in  it  than  in  any  other  organ. 

It  forms  no  part  of  our  intention  ib  treat  of  the  varieties  of 
inflammation:  they  depend  principally  on  the  structure  of  the 
organ  which  is  affected,  on  the  violence  and  rapidity  of  the 
symptoms,  and  on  its  effects. 

Is  not  the  lurgescence  of  an  inflamed  part,  occasioned  in  the 
same  manner,  as  in  parts  subject  to  erection,  as  the  corpora 
cavernosa  of  the  penis  and  of  the  clitoris,  the  nipples,  the  iris, 
&c.?  In  erection  of  the  penis,  as  in  inflammation,  there  is  an  ir- 
ritation, a determination  of  fluids  to  the  part,  an  increase  of  sen- 
sibility and  contractility;  yet  its  condition  is  not  that  of  inflam- 
mation. Nature  has  so  disposed  the  organization  of  these  parts, 
that  they  can  sustain,  without  injury,  those  instantaneous  aug- 
mentations of  vital  energy,  necessary  to  the  exercise  of  the  func- 
tions performed  by  the  organs  to  which  they  belong.  As  in 
inflammation,  these  congestions  disappear,  when  the  cause  of 
irritation  has  ceased  to  act;  thus,  the  pupil  dilates,  because  the 
iris  recedes,  when  the  eye  is  no  longer  exposed  to  the  rays  of  a 
vivid  light.  The  penis  returns  to  its  naturally  flaccid  and  soft 
state,  when  no  irritation  operates  to  determine  to  it  the  fluids 
whose  presence,  as  long  as  the  erection  lasts,  is  easily  explained 


55 


by  the  continuance  of  the  irritation,  without  its  being  necessary 
to  have  recourse  to  mechanical  explanations,  to  account  for  that 
phenomenon.  When  the  irritation,  which  produces  the  vital 
turgescence  of  the  penis  or  iris,  is  carried  too  far,  or  continues 
too  long,  the  natural  congestion  becomes  morbid.  It  is  well 
known,  that  priapism  is  frequently  attended  with  mortification 
of  the  penis,  and  that  the  too  long  continued  action  of  light  on 
the  eve,  brings  on  inflammation  of  that  organ. 

The  preceding  observations  on  inflammation,  shew,  that  an 
acquaintance  with  its  phenomena  is  useful,  even  in  a phvsio- 
logical  point  of  view.  The  vital  processes,  which  in  some  organs 
take  place  in  so  obscure  a manner,  that  they  are  imperceptible, 
acquire  in  infiammattion  a character  of  rapidity  and  intensity, 
which  renders  it  much  easier  to  observe  and  recognize  them. 
Considered  in  a general  and  abstract  point  of  view',  and  merely 
with  a reference  to  its  object,  inflammation  may  be  considered 
as  a means  emploved  by  nature,  to  repel  the  influence  of  noxious 
agents,  which,  when  introduced  within  the  body,  or  on  its  sur- 
face, she  has  no  power  of  resisting,  but  by  a more  active  deve- 
lopment of  the  powers  which  animate  it. 

During  the  severe  winter  of  1793,  the  chemist  Pelletier  re- 
peated the  celebrated  experiment  of  freezing  mercury,  and  ob- 
tained a solid  ball  in  the  bulb  of  a barometer,  which  he  had  for 
a long  while  kept  immersed  in  the  midst  of  a quantity  of  ice, 
continually  moistened  with  nitric  acid.  When  the  metal  had 
attained  a completely  solid  state,  he  drew  the  ball  from  the  bulb, 
and  placed  it  on  his  hand.  The  heat  of  the  part,  joined  to  that 
of  the  atmosphere,  soon  restored  the  quicksilver  to  its  fluid 
state:  at  the  same  instant,  he  experienced  in  his  hand  so  intoler- 
able a degree  of  cold,  that  he  was  obliged  to  drop  the  quicksilver 
instantly.  There  soon  came  on,  in  the  painful  and  chilled  part, 
a phlegmonous  inflammation,  which  was  cured  by  resolution. 
Quicksilver,  in  a solid  state,  is  one  of  the  coldest  bodies  in  na- 
ture: how  very  rapid  the  caloric  must  have  been  carried  oflT  in 
this  case,  and  how  deep  the  impression  must  have  been  in  the 
palm  of  the  hand,  doubly  aflFected  by  the  cold,  and  by  the  vital 
re-action,  which  terminated  in  inflammation!  I have  produced 
a similar  effect,  by  endeavouring  to  melt  a piece  of  ice  in  my 
hand,  during  the  heat  of  summer.  In  this  experiment,  the  im- 


56 


pression  of  cold  is  soon  succeeded  by  a sensation  of  acute  paia 
and  extraordinary  throbbings,  in  the  hand  and  fore  arm.  When 
the  two  hands  are  afterwards  compared,  that  which  held  the 
piece  of  ice  is  extremely  red,  from  the  congestion  of  blood  in 
the  cutaneous  capillary  tissue,  and  is  very  different  in  its  ap- 
pearance, from  that  which  was  not  the  subject  of  experiment. 

Analogous  facts,  if  seriously  considered,  should  induce  the 
foll6wers  of  Brown  to  apply  to  the  effects  of  cold,  the  distinction 
which  he  applied  to  debility,  of  direct  and  indirect.  They 
would  have  no  difficulty  in  ascertaining,  that  in  its  medical  ap- 
plication, that  negative  state  of  caloric,  which  is  directly  debili- 
tating, may,  nevertheless,  by  the  re-action  which  it  excites,  be 
considered  as  an  indirect  tonic. 

§ X.  OF  THE  SYSTEM  OF  THE  GREAT  SYMPATHETIC  XERVES. 

. The  great  sympathetic  nerves  are  to  be  considered  as  the  bond 
destined  to  unite  the  organs  of  the  nutritive  functions,  by  whose 
action  man  grows,  is  evolved,  and  incessantly  repairs  the  con- 
tinual waste  attending  the  vital  motions.  They  form  a nervous 
system,  very  distinct  from  the  system  of  the  cerebral  nerves; 
and,  as  the  latter  are  the  instruments  of  the  functions  by  which 
we  hold  intercourse  with  external  objects,  the  great  sympathetic 
nerves  supply  motion  and  life  to  the  organs  of  the  inward,  as- 
similating, or  nutritive  functions. 

In  animals  without  vertebrae,  ma}'^  not  the  nervous  system, 
which  floats  in  the  great  cavities  with  the  viscera  which  they 
contain,  be  considered  as  consisting  entirely  of  the  great  sympa- 
thetics?  These  nerves  are  principally  distributed  to  the  organs 
of  inward  life,  whose  activity,  in  those  animals,  seems  to  grow, 
in  proportion  as  their  external  senses,  and  their  faculty  of  loco- 
motion, are  imperfect.  If  the  great  sympathetics  exist  in  all  the 
animals  which  have  a distinct  nervous  system,  do  they  not,  in 
an  especial  manner,  contain  the  principle  of  vegetable  life,  essen- 
tial to  the  existence  of  every  organized  body  possessing  the 
power  of  digestion,  absorption,  circulation,  secretion  and  nutri- 
tion? Finally,  is  it  not  probable,  that  in  man,  the  system  of  the 
great  sympathetic  nerves  has  a very  great  share  in  occasioning 
a number  of  diseases,  and  that  the  impressions  with  which  pa- 


57 


tients  are  affected,  are  referred  to  their  numerous  ganglions, 
while  the  brain  is  exclusively  the  seat  of  intellect  and  thought?* 

These  suggestions  will,  doubtless,  be  answered  in  the  affirma- 
tive, if  one  consider  the  origin,  the  distribution  and  the  peculiar 
structure  of  these  nerves,  the  acute  sensibility  of  their  branches, 
as  well  as  the  disorders  attending  their  injury. 

Extended  along  the  vertebral  column,  from  the  base  of  the 
skull  to  the  lower  part  of  the  sacrum,  these  great  nerves,  in 
some  measure  parasitic,  do  not  arise  from  the  branches  supplied 
them  by  the  fifth  and  sixth  pairs  arising  from  each  side  of  the 
brain:  they  live  and  are  nourished,  as  it  were,  at  the  expense 
of  all  the  nerves  of  the  spinal  marrow,  from  which  they  receive 
branches,  so  that  there  is  not  one  of  them,  from  which  one  can 
say,  that  the  great  sympathetics  arise  exclusively.  The  numer- 
ous ganglions  which  are  distributed  along  their  course,  divide 
them  into  so  many  small  systems,  from  which  arise  the  nerves 
of  the  organs  nearest  to  them.  Amid  these  bulgings,  consider- 
ed by  several  physiologists,  as  so  many  little  brains,  in  which 
is  performed  the  elaboration  of  the  fluid  which  they  transmit  to 
the  nerves,  no  one  is  of  more  importance  than  the  semi-lunar 
ganglion,  situated  behind  the  organs  which  occupy  the  epigastric 
region,  and  from  which  those  nerves  originate,  which  are  dis- 
tributed to  the  greater  part  of  the  viscera  of  the  abdomen.  It  is 
to  the  region  occupied  by  that  ganglion,  in  which  the  great  sym- 
pathetic nerves  unite,  and  which  may  be  considered  as  the  cen- 
tre of  the  system  formed  by  their  union,  that  we  refer  all  our 
agreeable  sensations;  there  it  is  that  we  feel  in  sadness,  a con- 
striction which  is  commonly  referred  to  the  heart.  Thence  in 
the  sad  emotions  of  the  soul,  seem  to  originate  those  painfuT 
irradiations  which  trouble  and  disorder  the  exercise  of  all  the 
functions.f 

* These  opinions  on  the  lises  of  the  great  sympathetic  nerves,  are  explained 
in  my  Essay  on  the  connexion  of  Life  with  the  circulatioti.  This  Essay  was 

published  before  any  thing  that  has  appeared  on  the  same  subject Consult 

the  “ Memoires  de  la  Societe  Medicale  pour  I’an  VII.” 

j-  Consult  on  the  subject  of  the  epigastric  centre,  Van  Helmont,  who  calls 
it  the  archeus;  Buffon,  Borden,  Barthez  and  Lacaze,  who  give  It  the  name  of 
the  phrenic  centre,  because  they  ascribe  to  the  diaphragm,  what  belongs  to  the 
nervous  ganglions  placed  in  front  of  its  crura. 

H 


58 


The  numerous  filaments  of  the  great  sympathetic  nerves  are 
finer,  they  are  not  of  the  same  whitish  colour,  nor  of  the  same 
consistence  as  the  filaments  of  the  cerebral  nerves.  On  that  ac- 
count they  are  less  easily  dissected,  the  nervous  fibrillaeare  less 
distinct,  their  reddish  chords  are  moister,  and  they  appear  form- 
ed of  a more  homogeneous  substance:  their  membranous  cover- 
ings are  less  considerable.  They  are  likewise  endowed  with  a 
more  acute  and  more  delicate  sensibility.  Every  one  knows  the 
danger  attending  wounds  of  the  mesentery,  a membranous 
duplicature,  in  itself  insensible,  but  containing  such  numerous 
nerves  destined  to  the  intestinal  tube,  that  the  most  pointed  in- 
strument can  scarcely  wound  the  mesentery,  without  injuring 
some  of  their  branches.  The  pain  attending  affections  of  the 
great  sympathetic  nerves,  is  of  a very  peculiar  kind;  it  leads 
directly  to  the  extinction  of  the  vital  power.  It  is  a well-known 
fact,  that  a bruise  of  the  testicles  overpowers,  in  a moment,  the 
strongest  man.  Every  one  knows,  that  patients  who  die  of 
strangulated  hernia,  of  volvulus,  or  of  every  other  aflFection  of 
the  same  kind,  die  in  the  most  distressing  anguish,  their  heart 
feels  oppressed,  and  they  are  tormented  with  constant  vomiting. 
Intestinal  and  nephritic  colics  are  attended  with  the  same  sort 
of  pain;  that  attending  injection  of  the  tunica  vaginalis  in  hydro- 
cele, is  of  the  same  kind.  And  one  expects  a favourable  event 
of  the  operation,  only  in  those  cases  in  which  the  patient  has 
fell  pain  along  the  spermatic  chord,  in  the  course  of  the  sper- 
matic nerves,  which  arise,  as  it  is  well  known,  from  the  renal 
plexus.  In  three  cases  of  wounds  of  the  abdomen,  I was  led  by 
the  nature  of  the  pain  which  the  patients  suffered,  to  prognos- 
ticate that  the  wounds  had  penetrated;  the  event  justified  my 
prognostic.  In  all  these  affections  of  the  great  sympathetic 
nerves,  the  pulse  is  frequent  and  hard,  the  face  is  covered  with 
a cold  sweat,  the  features  are  sunk;  all  the  symptoms  are  alarm- 
ing and  soon  terminate  fatally. 

The  use  of  the  system  of  the  great  sympathetic  nerves  is,  not 
merely  to  establish  a closer  connexion  and  a greater  union  be- 
tween all  the  organs  which  perform  the  functions  of  assimilation, 
but  likewise  to  free  those  parts  from  the  influence  of  the  will. 
A power  of  the  mind  so  fickle  and  so  varying,  that  life  would 
be  in  constant  danger,  if  we  had  it  in  our  power  to  stop  or 


59 

suspend  the  exercise  of  functions  with  which  life  is  essentially 
connected. 

If  we  consider  what  are  the  organs  to  which  the  functions  of 
assimilation  are  intrusted,  and  which  receive  their  nervous  in- 
fluence from  the'  great  sympathetic  nerves,  we  shall  find,  that 
the  action  of  the  greater  number,  is  wholly  independent  of  the 
control  of  the  will.^  The  heart,  the  stomach,  the  intestinal 
canal,  &c.  do  not  obey  the  will,  and  seem  to  possess  a more 
insulated  and  more  independent  existence,  and  to  act  and  rest, 
without  any  influence  on  our  part.  Some  of  these  organs,  as  the 
bladder,  the  rectum,  and  the  muscles  of  respiration,  which  do 
not  receive  their  nerves  exclusively  from  the  great  sympathetics, 
are  obedient  to  the  will,  and  receive  from  the  brain  the  principle 
of  motion,  the  former,  from  the  branches  which  the  sacral  nerves 
send  to  the  hypogastric  plexuses;  the  diaphragm,  from  the  nerves 
which  it  receives  from  the  fifth  and  sixth  cervical  pairs. 

The  great  sympathetic  nerves  supply  the  diaphragm,  the 
rectum,  and  bladder,  only  with  nerves  of  sensation.  This  pro- 
vision was  a very  necessary  one,  for,  if,  as  is  the  case  with  the 
heart,  and  the  intestines,  these  parts  had  received  their  nerves 
of  motion  from  the  great  sympathetics,  their  action  would  have 
been  independent  of  the  will,  as  is  the  case  with  all  the  parts 
which  these  nerves  supply  with  motion.  The  bladder  and  rectum, 
placed  at  the  extremities  of  the  digestive  apparatus,  and  destined 
to  serve  as  reservoirs  to  the  excrementitious  residue  of  our  solid 
and  liquid  aliments,  would  have  been  constantly  evacuating 
their  contents,  as  fast  as  the  substances  which  are  destined  to 
be  retained  within  them  for  some  time,  reached  their  cavity. 

On  the  other  hand,  if  the  diaphragm  had  received  its  nerves 
of  motion  from  the  great  sympathetics,  respiration  would  have 
ceased  to  be  a voluntary  function,  of  which  we  might  at  pleasure 

* All  those  parts  which  receive  their  nerves  from  ganglions,  are.  equally 
independent.  Professor  Chaussier  thinks,  that  the  upper  filaments  of  the 
great  sympathetic  nerves,  ascend  along  the  internal  carotid,  and  join  the 
sphenopalatine  and  lenticular  ganglions. — M Ribes  thinks  he  has  ascertained 
by  dissection,  that  several  very  long  and  slender  filaments  follow  the  course  of 
the  branches  of  the  internal  carotid,  and  like  them  are  sent  to  the  base  of  the 
brain,  beyond  which  they  cannot  be  traced.  I have  myself  observed,  in  dissec- 
tion, these  filaments  around  the  branches  of  the  internal  carotid  artery,  but  I 
had  always  considered  them  to  be  formed  of  cellular  substance. 


60 


accelerate,  slacken,  or  even  completely  suspend  the  action.  To 
prove  that  the  act  of  respiration  is  under  the  control  of  the  will, 
we  may  have  recourse  to  analogy,  and  adduce  the  instance  of 
reptiles,  as  lizards,  frogs, serpents,  salamanders,  and  toads,  which 
are  cold-blooded  animals,  and  in  which  this  function  is  manifrstly 
voluntary.  We  may  further  mention  those  slaves,  who,  we  are 
told  by  Galen,  put  themselves  to  death,  when  summoned  before 
their  executioners  or  judges.  According  to  that  physiologist, 
and  others,  they  choked  themselves,  by  swallowing  their  tongue. 
But  it  is  sufficient  to  know  how  the  muscles  that  bind  down  the 
tongue  are  situated,  and  the  degree  of  motion  which  they  allow, 
to  see  how  little  ground  there  is  for  that  opinion.  The  action  of 
the  brain  would,  in  that  case,  have  been  no  longer  necessary  to 
the  maintenance  of  life;  in  an  animal  without  a brain,  respira- 
tion would  have  continued,  and  the  circulation  would  not  have 
been  interrupted.  The  death  of  that  viscus  would  not  have  been 
attended  with  the  sudden  death  of  all  the  rest. 

The  nerves  which  arise  from  the  spinal  marrow,  and  which 
give  to  the  diaphragm  the  power  of  contraction,  a power  which 
that  muscle  loses  suddenly,  if  these  nerves  be  tied,  appear  to 
me  the  chief  links  which  unite  the  internal  assimilating  or  nu- 
tritive functions,  to  those  which  keep  up  the  relation  of  the 
animal  with  external  objects.  Without  this  bond  of  union,  the 
series  of  vital  phenomena  would  have  been  less  close,  and  their 
dependence  less  necessary.  Had  it  not  been  for  the  necessity 
that  the  diaphragm  should  receive  from  the  brain,  by  means  of 
the  phrenic  nerves,  the  principle  which  determines  its  contrac- 
tions, acephalous  animals,  which  are  born  without  that  organ, 
might  continue  to  live  as  they  did  before  birth,  when  the  organs 
of  nutritive  life  received  blood,  which  had  undergone,  in  the 
lungs  of  the  mother,  the  changes  necessary  to  life.  But  where 
the  bond  which  united  them  to  the  mother  is  destroyed,  obliged 
themselves  to  produce  in  their  fluids,  the  necessary  changes,  by 
the  inhalation  of  the  vivifying  principle  contained  in  the  atmo- 
sphere, they  no  longer  can  obey  that  necessity;  the  organs 
of  respiration  are  deficient  in  the  principle  w'hich  should  excite 
them. 


61 


When  an  internal  inflammation  is  of  small  extent,’*'  and  is 
seated  in  a part  in  which  there  are  not  many  nerves,  and  whose 
tissue  yields  easily  to  the  humours  which  irritation  determines 
into  it,  the  whole  morbid  action  takes  place  in  the  affected  part, 
and  the  general  order  of  the  functions  is  not  sensibly  deranged. 
But  when  inflammation  takes  place  in  a part  endowed  with 
much  sensibility,  or  of  a close  texture,  as  the  fingers  and  toes, 
then  fever  comes  on,  because  a sympathy  in  the  morbid  action 
takes  place,  between  the  diseased  part  and  the  rest  of  the 
system.  This  diffusion  of  the  local  action  almost  infallibly  takes 
place,  when  inflammation  occurs  in  one  of  the  organs  of  the 
assimilating  functions.  This  effect  may  be  considered  as  uni- 
form, though  Morgagni  mentions  several  instances  of  inflamma- 
tion of  the  liver,  marked  by  no  peculiar  symptoms. 

A knowledge  of  the  great  sympathetic  nerves  accounts  for 
this  difference.  When  an  external  part  is  affected  with  inflam- 
mation, the  irritation  which  it  suffers,  is  by  means  of  its  nerves 
propagated  to  the  brain,  which  by  a re-action,  called  by  Vicq- 
d’Azyr  (who  on  this  subject  has  only  developed  the  opinions  of 
Van  Helmont)  internal  nervous  action,  transmits  that  irritation 
to  the  heart,  to  the  organs  of  respiration,  of  digestion  and 
of  secretion,  in  which  the  phenomena,  denoting  a febrile  state, 
are  principally  evolved.  When,  on  the  contrary,  the  heart,  the 
lungs,  or  any  other  internal  organ  is  affected  with  acute  in- 
flammation, all  the  viscera  partake  in  the  derangement  with 
which  any  one  of  them  is  affected,  and  without  the  intervention 
of  the  brain.  They  are  all  intimately  connected  by  the  filaments 
which  they  receive  from  the  great  sympathetic  nerves;  and,  by 
means  of  that  nervous  system,  which  is  in  especial  manner  ap- 
propriated to  them,  they  carry  on  a more  intimate  intercourse 

* A thousand  pustules  in  the  small  pox  occasion  only  a moderate  degree  of 
fever,  if  they  are  at  a distance  from  each  other;  but  if  the  disease  is  confluent, 
that  is,  if  the  pustules  are  close  together  and  run  into  each  other,  the  fever 
becomes  considerable  and  the  patient’s  life  is  endangered.  The  fleshy  granu- 
lations which  sprout  in  abundance  from  an  ulcerated  surface,  are  so  many 
small  phlegmons  unaccompanied  by  a febrile  state,  but  if  brought  close  to 
each  other  by  irritation,  that  condition  will  not  fail  to  ensue.  Vaccination  is  not, 
in  the  greater  number  of  cases,  attended  by  the  slightest  febrile  action,  if,  as 
I have  always  done,  the  punctures  are  made  at  a certain  distance  from  each 
«ther,  so  that  the  inflammatory  areols  may  not  run  into  each  other. 


62 


of  sensations  and  aflFections.  Besides,  the  derangement  of  the 
important  functions  intrusted  to  the  diseased  organs,  is  neces- 
sarily attended  with  proportionate  changes  in  all  the  acts  of  the 
animal  economy,  in  the  same  manner,  no  doubt,  as  the  defect 
of  one  wheel  interrupts  or  disturbs  the  mechanism  of  the  whole 
machine; 

There  exists  in  the  stomach  an  union  of  the  cerebral  and 
sympathetic  nerves,  which  explains  the  manifest  dependency, 
in  which  that  one  of  the  three  supports  of  life  is  found  with  the 
brain;  a dependency  so  marked,  that  every  strong  aflFection  of 
the  soul,  every  violent  agitation  of  the  mind,  weakens  or  even 
totally  suspends  the  action  of  digestion  in  the  stomach. — This 
combination  of  cerebral  and  sympathetic  nerves  likewise  ac- 
counts for  a phenomenon,  which  was  mentioned  in  speaking  of 
the  influence  of  habit  on  the  action  of  the  organs.  The  stomach 
diflTers  essentially  from  the  intestinal  canal;  for,  far  from  getting 
accustomed  to  the  impression  of  emetics,  so  as  to  become  by 
degrees  less  sensible  to  their  action,  as  the  intestines  to  the 
action  of  purgatives,  though  three  grains  of  tartar  emetic  could 
at  first,  scarcely  excite  it,  half  a grain  only  of  that  salt  is  able  to 
bring  on  vomiting,  when  b}’  frequent  use,  it  has  acquired  the 
habit  of  the  motions  excited  by  its  action.  Is  it  not  in  that  case 
with  the  stomach,  as  with  a limb,  whose  muscles  perform  mo- 
tions with  the  greater  ease  and  facility,  when  they  have  been 
often  practised. 

§ XL  OF  THE  RELATIONS  OF  PHYSIOLOGY  TO  SEVERAL  OTHER 

SCIENCES. 

It  would  be  entertaining  a very  incorrect  notion  of  the  science 
of  living  man,  to  imagine  with  some  authors,  that  it  solely  con- 
sists in  the  application  of  the  laws  of  natural  philosophy,  to  the 
explanation  of  the  phenomena  of  the  animal  economy.  Phy- 
siology is  an  independent  science;  resting  upon  truths  of  its 
own,  which  it  draws  from  the  observation  of  those  actions, 
which,  in  their  aggregate  succession  and  connexion,  constitute 
life.  It  is  enriched,  it  is  true,  with  facts  furnished  to  it  by 
natural  philosophy,  chemistry,  and  mathematics;  but  what  it 
has  borrowed  from  these,  is  accessory  merely,  and  does  not 
form  an  essential  part  of  the  edifice  of  the  science.  Thus,  the 


63 


better  to  understand  the  mechanism  of  hearing  and  vision^ 
physiology  borrows  from  acoustics  and  optics,  elementary  no- 
tions on  sound  and  light;  and,  in  order  to  obtain  a more  correct 
knowledge  of  the  nature  of  our  solids  and  fluids,  and  of  the 
manner  in  which  animal  substances  are  constantly  passing  from 
the  one  to  the  other  of  these  two  conditions,  physiology  calls  in 
the  aid  of  chemistry.  Thus,  geometry  and  mechanism  furnish  it 
with  the  means  of  better  understanding  the  advantageous  form 
of  the  organs,  and  the  perfection  of  their  structure. 

No  study  carries  along  with  it  a more  lively  interest,  than 
that  of  the  admirable  relations  existing  between  the  conforma- 
tion of  our  parts,  and  the  external  objects,  to  which  they  are 
applied.  These  relations  are  calculated  with  such  precision, 
and  laid  down  with  such  accuracy,  that  the  organs  of  sense  and 
of  motion,  considered  in  this  point  of  view,  may  be  regarded 
as  the  model  of  the  most  ingenious  productions  of  art.  So  true 
it  is,  in  the  words  of  the  great  physician  of  Pergamus,  that 
nature  did  every  thing  before  art,  and  better.* 

At  the  beginning  of  the  last  century,  geometrical  physicians, 
deceived  by  an  appearance  of  rigid  precision,  attempted  to  ex- 
plain every  thing  by  the  calibre  of  vessels,  their  length,  their 
curvatures,  the  compound  ratio  of  the  action  of  solids  and  the 
impulse  of  fluids.  Hence  were  formed  theories  so  very  im- 
perfect, that,  as  we  shall  see,  in  treating  of  several  points  of 
physiology,  and  especially  of  the  force  with  which  the  heart 
acts,  not  one  of  those  who  proposed  them,  coincides  with  those 
who  have  since  followed  their  track.  However,  it  does  not 
admit  of  a doubt,  that  there  occur  in  the  animal  machine, 
effects  which  are  referable  to  the  laws  of  hydraulics.  The  brain, 
for  example,  required  a large  and  constant  supply  of  arterial 
blood,  vivified  by  recent  circulation  through  the  lungs;  but  the 
too  rapid  and  abrupt  access  of  that  fluid  in  the  brain,  might 
have  disordered  its  structure.  Nature,  therefore,  has,  as  we 

* ^andoquldem  naiura,  ut  arbitror,  et  prior  tempore  sit,  et  in  operibus  magis 
sapiens  quam  ars. — Galenus,  de  vsu  partium,  lib.  VII.  cap,  13. 

It  was  from  observing  the  manner  in  which  nature  prevents  the  diffusion  of 
light  in  the  globe  of  the  eye,  that  Euler  was  led  to  the  improvement  of  his 
astronomical  telescopes. 


s,  ' 


64 

shall  mention  in  the  article  of  the  cerebral  circulation,  employ- 
ed all  the  hydraulic  resources  in  her  power,  to  break  the  force 
with  which  the  blood  enters  the  brain,  and  to  slacken  its  course. 

Has  man  ever  applied  the  laws  of  hydraulics  in  a more 
felicitous  manner  than  nature,  in  the  rete  mirabile  formed  at 
the  base  of  the  brain  by  the  carotids  of  quadrupeds?  An 
arrangement  truly  remarkable,  without  which,  the  blood  con- 
veyed to  the  brain  by  those  arteries,  impelled  by  a force 
superior  to  that  of  the  human  heart,  and  not  having  to  over- 
come the  resistance  of  its  own  gravity,  would  infallibly  have 
occasioned  a disorganization  of  that  organ,  whose  consistence 
is  so  soft. 

As  to  the  application  w’hich  is  allowable  of  mathematical 
sciences,  it  may  be  said,  that,  as  in  physiology,  but  little  is 
absolutely  certain,*  and  much  merely  probable,  we  can  reckon 
only  on  probabilities,  and  seek  our  elements  in  facts  deduced 
from  observation  or  experience:  facts,  which  when  collected 
and  multiplied  to  a certain  degree,  lead  to  results  of  equal  value 
with  truths  absolutely  demonstrated. 

The  phenomena  presented  by  living  bodies  vary  incessantly, 
in  their  activity,  their  intensity,  and  their  velocity.  How  can 
mathematical  formulae  apply  to  such  variable  elements?  As  well 
might  you  inclose  in  a frail  vessel,  hermetically  sealed,  a fluid 
subject  to  expansion,  and  of  variable  bulk.  The  motions  of  pro- 
gression in  man  and  in  the  animals,  afford,  nevertheless,  suffi- 
ciently correct  applications  of  calculation.  Calculation  may 
likewise  be  applied  with  advantage,  to  the  measurement  of  the 
results  of  our  different  secretions,  to  ascertain  the  quantity  of 
air,  or  of  aliment,  introduced  into  our  organs,  &c. 

Among  the  principal  causes  which  have  retarded,  in  a consi- 
derable degree,  the  progress  of  physiology,  may  be  enumerated 
the  mistake  of  those  who  have  endeavoured  to  explain  all  the 
phenomena  of  living  bodies,  by  a single  science,  as  chemistry, 
hydraulics,  Sfc.,  while  the  union  of  all  these  sciences  will  not 

account  for  the  sum  of  these  phenomena.  The  abuse,  however, 

m 

I 

* This  is  to  be  understood,  as  applying  only  to  the  causes  of  the  pheno- 
mena, and  not  to  the  phenomena  themselves;  for  physiology  is  perhaps  richer 
tiian  any  other  science,  in  facts  unquestionable,  and  easily  ascertained  by 
observation. 


65 


of  these  sciences,  should  not  be  a reason  for  setting  them  aside 
altogether.  The  facts  obtained  from  natural  philosophy,  che- 
mistry, mechanics,  and  geometry,  are  so  many  means  applicable 
to  the  solution  of  the  great  problem  of  the  vital  economy;  a 
solution  which,  though  as  yet  undiscovered,  should  not  be  con- 
sidered as  unattainable,  and  to  which  we  shall  approach  the 
nearer,  as  we  attempt  it  with  a greater  number  of  data.  But 
it  cannot  be  too  often  repeated,  that  he  alone  can  hope  for  that 
honour,  who,  in  the  application  of  the  laws  of  natural  philosophy 
to  living  bodies,  will  take  into  account  the  powers  inherent  in 
organized  nature,  which  control,  with  supreme  influence,  all 
the  acts  of  life,  and  modify  the  results  that  appear  most  to  de- 
pend on  the  laws  by  which  inorganic  bodies  are  governed. 

Anatomy  and  physiology  are  united  by  such  close  relations, 
that  it  has  been  an  opinion  with  some,  that  they  are  absolutely 
inseparable.  If  physiology,  say  they,  has  for  its  object,  a know- 
ledge of  the  functions  carried  on  by  our  organs,  how  is  one  to 
understand  their  mechanism,  without  knowing  the  instruments 
by  which  they  are  performed?  One  might  as  well  attempt  to  ex- 
plain the  manner  in  which  the  hand  of  a watch  performs  the  circle 
of  its  diurnal  revolution,  without  understanding  the  springs  and 
numerous  wheels  which  set  it  in  motion.  Haller  is  the  first  who 
established  the  connection  between  anatomy  and  physiology,  and 
who  illustrated  it  in  his  great  work.  Since  Haller,  a great  num- 
ber of  anatomists,  and  among  them  Sffimmering,*  in  a work 
recently  published,  have  combined,  as  much  as  possible,  these 
two  sciences;  the  latter,  in  treating  separately  of  each  system 
of  organs,  explains  what  is  best  known  of  their  uses  and  pro- 
perties. 

However  close  the  connexion  between  anatomy  and  physio- 
logy, they  have,  nevertheless,  appeared  perfectly  distinct  to  the 
greater  number  of  authors,  and  we  have  several  valuable  works 
on  anatomy,  of  which  physiology  occupies  but  a small  part. — 
This  manner  of  embracing  the  two  sciences  appears  to  me  at- 
tended with  the  greatest  advantage;  in  fact,  if  the  insulated  des- 
cription of  organs  suffices  to  the  physiologist  who  wishes  to 


* J.  Ch.  Soemmering',  de  corporis  humani  fabrifd.  6 vols.  8vo.  1804. 

I 


66 


study  their  functions,  that  method  is  attended  with  the  disad- 
vantage of  furnishing  few  truly  useful  views,  in  the  practice 
of  operative  surgery.  To  render  the  knowledge  of  the  human 
body  more  especially  applicable  to  the  practice  of  surgery,  it  is 
necessary,  not  only  to  consider  separately  the  different  parts, 
but  likewise  to  view  them  in  their  connexion,  and  to  determine 
precisely  their  relations.  The  anatomist,  who  knows  that  the 
principal  artery  of  the  thigh  is  the  crural, — that, continued  un- 
der the  name  of  popliteal,  it  passes  behind  the  knee  in  its  way  to 
the  leg, — that,  in  its  course,  it  supplies  with  branches  different 
parts  of  the  limb, — even  though  he  knew  perfectly  the  name, 
the  number  of  these  branches,  the  varieties  to  which  they  are 
subject,  the  parts  to  which  they  are  distributed,  would  never- 
theless possess  a knowledge  of  that  branch  of  the  system,  almost 
useless  in  the  treatment  of  the  diseases  with  which  it  may  be 
affected.  The  situation  of  the  artery,  its  direction,  the  parts 
which  surround  it,  its  precise  relations  to  each  of  them,  its  su- 
perficial or  deep  seated  course,  &c.  are  the  only  circumstances 
from  which  he  can  derive  any  advantage. 

He  who,  in  this  point  of  view,  cultivates  anatomy,  may  be 
compared  to  the  chemist;  in  the  same  manner  as  the  latter  is 
never  better  acquainted  with  a substance,  than  when  he  is  able 
to  decompose  it,  and  to  reproduce  it  from  a combination  of  its 
parts,  so  the  anatomist  is  well  acquainted  with  the  body  of  man, 
only,  when  having  studied  separately,  and  with  the  greatest  care, 
each  of  his  organs  and  each  of  the  systems,  formed  by  the  col- 
lection of  a certain  number  of  similar  organs,  he  is  able  to  assign 
to  each  of  (hem  its  place,  to  determine  its  relations,  and  the  pro- 
portions which  it  bears  in  the  structure  of  any  one  of  our  limbs. 
The  study  of  the  latter  is  much  more  difficult  and  extensive,  than 
that  of  the  former:  for,  the  chemist  who  decomposes  and  recom- 
pounds a well-known  substance,  phosphat  of  lime,  for  instance, 
attains  only  to  the  knowledge  of  its  constituent  principles,  and 
respectiv^e  proportions;  the  phenomena  of  situation  altogether 
escape  him.  The  anatomist,  on  the  other  hand,  who  knows  that 
such  a part  is  composed  of  bones,  of  muscles,  of  nerves,  of  ves- 
sels, must  know,  not  only  every  one  of  these  parts,  their  relative 
bulk,  but  the  exact  place  in  which  they  are  to  be  found. 


6f 


Anatomy,  pursued  in  this  spirit,  offers  a field  of  wide  extent! 
k is  the  art  which  Leibnitz  called  the  analysis  of  situation,  ana- 
lysis situs;  and  the  knowledge  of  it  is  too  important  not  to  re- 
quire a separate  place,  among  the  departments  of  medical  know- 
ledge. I will  not  pass  over  the  motives  that  are  alleged  for  com- 
bining anatomy  and  physiology  in  one  course  of  instruction* 
Anatomy,  confined  to  the  mere  description  of  the  organs,  is  too 
dry  and  fatiguing;  physiology  throws  over  it  interest  and  variety! 
it  helps  to  ensure  the  attention  of  the  hearers,  who  will  retain 
more  permanently,  what  they  have  listened  to  with  pleasure. 
Would  not  one  think  that  physiological  details  were,  for  an  au- 
dience, what  is  contrived  for  a sick  and  fioward  child,  in  the 
honey  that  is  rubbed  on  the  edge  of  the  cup,  to  disguise  the 
bitterness  of  the  draught  that  is  to  recal  him  to  life?  In  com- 
bining two  objects,  of  which  one  has  no  interest  but  that  of  use- 
fulness, whilst  the  other  is  engaging  as  well,  the  attention  will 
he  not  merely  divided,  but  altogether  distracted,  and  the  mind 
of  those  who  read  or  listen,  will  skim  over  dry  details,  to  seize 
with  avidity  what  furnishes  more  to  its  activity  of  intelligence* 
Anatomy  is  to  physiology,  what  geography  is  to  history.  Gene- 
ral considerations  on  the  situation,  the  size,  the  form,  the  rela- 
tions, the  structure  of  an  organ,  are  an  indispensable  preparation 
to  the  perfect  understanding  of  its  functions;  accordingly,  you 
shall  find  much  anatomy  in  physiological  treatises,  as  you  find 
much  geographical  detail  in  faithful  historians* 

1 have  said  enough,  I trust,  to  escape  the  reproach  of  not 
having  filled  my  book  with  anatomical  descriptions,  from  the 
multitude  of  excellent  works  we  possess  on  the  anatomy  of  the 
human  body.  Let  us  now  enquire  what  relation  physiology 
bears  to  Comparative  Anatomy. 

If  a machine  can  be  perfectly  known,  only  after  taking  it  to 
pieces,  down  to  its  simplest  elements;  if  the  mechanism  of  the 
whole  action  is  conceived,  only  by  separately  studying  the  action 
of  each  different  part,  tomparative  anatomy,  by  aid  of  which 
we  can  study,  in  the  great  chain  which  the  animal  kinds  com- 
pose, the  separate  action  of  each  organ,  appreciate  its  absolute 
or  relative  importance,  consider  it,  at  first,  insulated  and  reduced, 
So  to  speak,  to  its  own  powers,  in  order  to  determine  what  part 
it  bears  in  the  carrying  on  of  a function;  comparative  anatomy 


68 


is  of  absolute  necessity  to  him  who  would  make  great  progress 
in  the  knowledge  of  man:  it  may  be  looked  upon  as  a sort  of 
analytic  method^  by  means  of  which  we  more  completely  attain 
to  the  knowledge  of  ourselves. 

In  order  to  conceive  rightly  the  operations  of  the  human  in- 
tellect, and  explain  the  generation  of  the  faculties  of  the  soul, 
metaphysicians  have  imagined  a statue,  into  which  they  have 
infused  a gradual  animation,  by  investing  it,  one  by  one,  with  our 
organs  of  sensation.  Now,  Nature  has  realised  in  some  sort  this 
dream  of  philosophy.  There  are  animals  to  which  she  has  en- 
tirely denied  the  organs  of  sight  and  hearing;  in  some,  taste  and 
smell  seem  to  have  no  separate  existence  from  touch;  in  others, 
she  has  exercised  a sort  of  analysis  on  a system  of  parts  which  all 
concur  in  one  function.  It  is  thus,  that  in  some  animals,  divest- 
ing the  organ  of  hearing  of  the  accessories  allotted  to  collect, 
transmit,  and  modify  the  rays  of  sound,  she  has  reduced  it  to  a 
simple  cavity,  filled  with  glutinous  fluid,  in  which  float  the  ex- 
tremities of  the  acoustic  nerve,  alone  fitted  to  receive  the  im- 
pression of  sound;  a fact  which  overthrows  all  the  hypotheses 
that  had  ascribed  this  sensation  to  other  parts  of  the  auditory 
apparatus. 

Of  all  the  physical  sciences.  Comparative  Anatomy  is  that 
which  furnishes  the  most  useful  facts  to  physiology.  Like  phy- 
siology, it  is  concerned  with  organized  living  beings:  there  is, 
therefore,  no  need  of  watching  against  the  false  applications,  so 
often  made  from  the  sciences,  whose  objects  are  matter  inor- 
ganic and  dead,  or  which  study,  in  living  beings,  only  the  gene- 
ral properties  of  matter.  Haller  was  so  well  aware  of  the  utility 
of  introducing  this  science  into  physiology,  that  he  has  brought 
together  the  greater  part  of  the  facts  known  in  his  time,  on  the 
anatomy  of  animals,  at  the  head  of  each  chapter  of  his  im- 
mortal work. 

This  general  consideration  of  living  and  animated  beings,  so 
well  adapted  to  unveiling  the  secret  of  our  organization,  has 
this  further  advantage,  that  it  enlarges  the  sphere  of  ideas  of 
him  who  applies  to  it.  Let  him  who  aspires  to  that  largeness  of 
conception,  so  requisite  in  medicine,  where  facts  are  so  multi- 
plied and  various,  explanations  so  contradictory,  and  rules  of 


conduct  so  unfixed,  cast  a general  glance  on  this  great  divisioE 
of  organized  beings,  of  which  many,  in  their  physical  structure, 
so  nearly  resemble  man; — he  will  see  the  sovereign  Architect 
of  the  world,  distributing  to  all  the  element  of  life  and  activity, 
giving  to  some  a less  power  of  motion,  to  others  more;  so  that 
formed  all  on  one  model,  they  seem  only  the  infinitely  varied, 
but  gradual  shades  of  the  same  form,  if  forms  have  shades  like 
colours:  never  passing  abruptly  from  one  to  another,  but  rising 
or  falling  by  gentle  and  due  degrees;  covering  the  interval  that 
separates  two  different  beings,  with  many  species  that  serve  as  a 
transition^  from  one  to  the  other,  and  which  present  a continuous 
series  of  advancement  or  degradation:  organization  being  con- 
stantly simplified,  in  descending  from  man  to  the  inferior  crea- 
tures; but  rising  in  complexity,  in  re-ascending  from  those  ani- 
mals to  man,  who  is  the  most  complex  being  in  nature,  and  was 
justly  considered,  by  ancient  philosophy,  as  the  master-piece  of 
the  Creator. 

If  the  intimate  structure  of  our  organs  totally  eludes  our  in- 
vestigation, it  is,  that  the  finest  and  most  delicate  of  their  consti- 
tuent parts  are  of  such  minute  dimensions,  that  our  senses  have 
no  hold  on  them.  It  is  then  well  to  have  recourse  to  analogy, 

* The  conception  is  noble  and  interesting  of  a scale  of  being,  which,  as  was 
said  by  C.  Bonnet,  connecting  all  the  worlds,  embracing  all  the  spheres,  should 
extend  from  the  atom  to  the  most  exalted  of  cherubim.  Without  carrying  it  so 
high  or  so  low,  if  we  confine  it  to  the  natural  beings  with  which  we  are  well 
acquainted,  and  wliich  can  be  brought  under  observation,  it  will  be  seen,  that 
the  idea  is  not  so  chimerical  as  some  writers  of  most  respectable  authority  have 
supposed  it.  The  plan  traced  by  C.  Bonnet  is  evidently  defective;  we  find  in 
it  beings  set  beside  each  other,  that  have  but  faint  lines  of  resemblance,  or  alto- 
gether illusive.  The  present  state  of  the  natural  sciences  would  allow  of  its 
being  better  done:  one  might  try  at  least  for  all  bodies  what  Jussieu  has  ex- 
ecuted with  regard  to  vegetable  productions;  and  if  this  undertaking,  in  the 
hands  of  men  the  most  able  to  bring  it  to  a successful  termination,  left  any  thing 
defective,  would  not  that  imperfection  be  an  indication  of  the  existence  of 
other  worlds,  or  of  lands  yet  unknown  on  the  globe  we  inhabit;  undiscovered 
regions,  where  those  animals,  and  plants,  and  minerals  would  be  found  which 
were  wanting  to  fill  up  the  gaps  in  the  immense  series  of  co-ordinate  ex- 
istence ? 

Demonstratum fuit  et  hoc,  nullam  rem  contrarias,  vel  omnino  multum  differentes 
qualitates  recipere  posse,  nisi  per  media  prius  iter fecerit. 

GalenuS,  de  usu partium,  lib.  4,  cap.  12. 


70 


and  to  study  the  organization  of  animals  that  exhibit  the  Satno 
organs  on  a larger  scale.  Thus,  the  cellular  texture  of  the  lungs, 
which  cannot  be  distinctly  shewn  in  man,  on  account  of  the  ex- 
treme minuteness  of  the  smallest  bronchiae,  may  be  satisfacto- 
rily seen  in  the  vesicular  lungs  of  salamanders  and  frogs.  In 
like  manner,  the  scales  which  cover  the  bodies  of  fishes  and 
reptiles,  or  the  legs  of  birds,  give  us  a just  idea  of  the  structure 
of  the  epidermis,  and  of  the  arrangement  of  its  small  scales, 
which  lie  over  each  other,  in  a part  of  their  surface. 

The  human  structure  being  more  complicated,  must  produce 
effects  more  numerous,  and  results  more  varied,  and  more  diffi- 
cult to  understand.  In  commencing  the  study  of  the  animal  or- 
ganization by  that  of  man,  we  do  not,  therefore,  follow  the  ana- 
lytical method,  we  do  not  proceed  from  what  is  simple,  to  what 
is  more  complex.  It  would  perhaps  be  an  easier  and  a more 
natural  way  of  arriving  at  a solution  of  the  grand  and  difficult 
problem  of  the  animal  economy,  to  begin  by  explaining  its  most 
simple  terms;  to  rise  by  degrees  from  plants  to  vegetating  ani- 
mals, as  polypi;  from  these  to  white-blooded  animals,  then  to 
fishes  and  reptiles;  from  the  latter  to  warm-blooded  animals, 
and  lastly  to  man  himself,  placed  at  the  head  of  that  long  series 
of  beings  whose  existence  becomes  complicated,  in  proportion 
as  they  approach  him. 

The  study  of  every  part  of  natural  history,  and  especially  of 
comparative  anatomy,  cannot  fail,  therefore,  to  prove  of  infinite 
advantage  to  the  physiologist;  a truth  well  expressed  by  the 
eloquent  M.  de  Buffon,*  who  says,  that  if  there  existed  no  ani- 
mals, the  nature  of  man  would  be  still  more  incomprehensible. 

I shall  say  nothing  of  the  well  known  relations  of  physiology 
to  medical  science,  of  which  it  is  justly  considered  as  the  base 
or  support.  Medicine,  called  by  some  the  art  of  healing,  by 
others  more  properly,  the  art  of  treating  diseases,  may  be  defined 
the  art  of  preserving  health,  or  curing  diseases,  or  of  rendering 
them  more  supportable;  medicine,  in  all  its  parts,  is  enlightened 
by  physiology,  and  cannot  have  a surer  guide.  Owing  to  a neglect 
of  this  auspicious  guide,  therapeutics  and  materia  medica  long 


Histoire  nat.  tom.  V.  12mo.  p.  241.  Discours  sur  la  nature  des  animaiix. 


71 


remained  involved  in  a mist  of  conjectures  and  hypothesis.  Phy- 
sicians should  never  for  a moment  forget,  that  as  a great  num- 
ber* of  diseases  consist  in  a derangement  of  the  vital  functions, 
all  their  efforts  should  tend  to  bring  back  sensibility  and  contrac- 
tility to  their  natural  condition;  that  the  best  classification  of  dis- 
eases and  of  medicines,  is  that  which  is  founded  on  a judicious 
distinction  of  the  vital  powers.  With  this  view  it  is  that  M. 
Alibert,  in  his  elements  of  materia  medica,  classes  medicines 
according  to  their  effects  on  sensibility  or  contractility,  and 
according  to  the  organs  on  which  their  action  is  particularly 
exerted. 

§ XII.  CLASSIFICATION  OF  THE  VITAL  FUNCTIONS. 

After  having  treated  separately  of  the  vital  powers  or  facul- 
ties, nothing  is  easier  than  to  arrange,  in  a clear  and  methodical 
order,  the  functions  carried  on  by  the  organs  which  these  pow- 
ers call  into  action.  The  term  function  might  be  defined,  means 
of  existence.  This  definition  would  be  the  more  just,  as  life  is 
only  the  exercise  of  these  functions,  and  as  it  ceases,  when  any 
one  of  the  more  important  can  be  no  longer  carried  on.  From 
not  distinguishing  the  faculties,  from  the  functions  which  are 
merely  the  acts  of  the  faculties  or  powers,  several  modern 
divisions,  though  far  preferable  to  the  old  classification  of  the 
functions  into  vital,  animal  and  natural,  are,  nevertheless^  defi- 
cient in  accuracy  and  simplicity.  Thus  Vicq-d’Azyr  in  the 
classification  of  the  phenomena  of  physiology,  inserted  in  the 
discourse  which  he  has  prefixed  to  his  work  on  Anatomy,  mis- 
takes the  cause  for  the  effect,  and  places  sensibility  and  irrita- 
bility among  the  functions,  and  commits  another  mistake,  by 
ranking  among  the  latter,  ossification,  which  is  but  a peculiar 
mode  of  nutrition,  belonging  to  parts  of  a hard  structure. 

The  best  method  of  classing  the  actions  which  are  pei'formed 
in  the  living  human  body  is,  doubtless,  that  by  which  they  are 
distributed  and  arranged  according  to  the  object  which  they 

* All  diseases  consist  in  physical  derangements,  as  solutions  of^l^ntinuity,  dis- 
placements, organic  alterations,  as  polypi,  aneurisms,  and  other  eC^tions  re- 
sulting from  organic  affection  andalteration  of  structure;  tiital  laitvi,  as  fevers, 
ataxi(g,  adynamia,  vesanise,  &c.  see  Nosographie  Cldrurgicale. 


72 


fulfil — Aristotle,  BuflFon,  and  especially  Grimaud,  have  laid  on 
that  base  the  foundation  of  a method  which  we  shall  adopt,  with 
the  modifications  which  we  are  about  to  mention. 

Aristotle  and  Buffon  had  observed,  that  among  the  acts  of  the 
living  economy,  some  were  common  to  all  beings  that  have  life, 
to  plants  and  animals  during  sleep  and  in  waking,  while  others 
seemed  to  belong  exclusively  to  man,  and  to  the  animals  which 
more  or  less  resemble  him.  Of  these  two  modes  of  existence, 
the  one  vegetative,  the  other  animal,  the  former  appeared  to 
them  the  more  essential,  as  being  more  diffused  and  consisting 
merely  in  the  assimilation  of  nutritive  molecules,  in  the  nutrition 
absolutely  necessary  to  the  preservation  of  the  living  being,'*' 
who,  as  his  substance  is  incessantly  wasting,  would  soon  cease  to 
exist,  if  these  continual  losses  were  not  always  repaired  by  the 
act  of  nutrition. 

Grimaud,  Professor  of  Physiology  at  Montpellier,  too  soon 
lost  to  the  science  which  he  cultivated  as  a philosopher  truly  de- 
serving that  name,  adopted  this  simple  and  luminous  division, 
developed  it  better  than  had  been  done  before  him,  and  uniform- 
ly followed  it  in  his  lectures  and  in  his  works-f  This  division  of 
the  functions  into  internal,  which  he  likewise  calls  digestive,  and 
into  external  or  loco-motive,  lately  brought  forward  under  the 
name  of  organic  and  animal,  the  former  of  which  terms  is  quite 
inaccurate  and  defective,  since  it  leads  to  a belief,  that  the 
animal  life  is  not  confided  to  organs,  and  that  these  vital  in- 

• Nam  anima  nutriti  va  etiam  aliis  inesi,  et prima  et  mojcima,  communis facultas 
emimne,  secundum  quam  omnibus  vivere  inest.  Aristot.  de  anim.  lib.  2.  cap.  4. 

In  his  MS.  lectures  on  Physiology,  he  seems  to  feel  a complacency  in  that 
division  which  he  had  in  a manner  appropriated  to  himself,  by  his  happy  illus- 
trations of  it,  and  by  the  changes  which  he  had  introduced  into  it  In  every 
lecture,  1 might  almost  say  in  every  page,  he  returns  to  this  division,  et^lains 
it,  dilates,  and  comments  upon  it.  “ The  functions,”  says  he,  “ may  be  divided 
“into  two  great  classes;  some  are  performed  in  the  interior  of  the  body,  and 
“ exclusively  belong  to  it;  others  take  place  outwardly  and  belong  to  external 
‘‘objects,  &c.”  The  digestive  power  presides,  in  his  opinion,  over  the  internal 
ftmetions,  whose  ol\ject  is  nutrition,  the  loco-motive  power  directs  the  external 
functions  “ It  is  by  means  of  the  organs  of  sense  that  the  animal  enlarges  his 
existence,  that  he  applies  and  distributes  it  on  the  surrounding  objects,  that 
he  take  cognizance  of  the  qualities  in  those  objects  which  concern  him;  it  is 
bv  means  of  the  muscles  essentially  obedient  to  the  organs  of  sense,  that  he 
ad:.p  s himself  to  those  objects,  that  he  places  hinjself  in  a manner  suited  t* 
the  mode  of  their  activity,  &c.” 


73 


struments  are  solely  employed  on  internal  life  or  nutrition 
(^Motus  asftimilationis^  Bacon;  Bias  alterativum^  Van  Heltnont): 
This  distinction  does  not  comprehend  the  whole  of  the  phe- 
nomena, and  does  not  embrace  the  sum  of  the  functions 
which  are  performed  in  the  animal  economy.  In  fact,  there  are 
not  found  in  the  two  great  classes  which  it  establishes,  the  acts 
by  which  animals  and  vegetables  re-produce  and  perpetuate 
themselves,  and  immortalize  the  duration  of  their  species.  All 
the  functions  destined  to  the  preservation  of  the  species  are  not 
included;  they  merely  relate  to  the  functions  subservient  to  the 
preservation  of  individuals. 

I have,  therefore,  thought  it  right  to  include  under  two  gene- 
ral classes,  in  the  first  place,  the  functions  which  belong  to  the 
preservation  of  the  species,  functions  without  which  man  might 
exist,  as  we  see  in  eunuchs,  but  without  which  the  human  spe- 
cies would  soon  perish,  from  a loss  of  the  power  of  reproduc- 
tion. In  laying  down  these  two  great  divisions,  I have  merely 
considered  the  object  and  end  which  each  function  has  to  fulfil. 
Among  the  functions  which  are  employed  in  the  preservation 
of  the  individual,  some  fulfil  this  office  by  assimilating  to  his 
own  substance  the  food  with  which  he  is  nourished;  the  others, 
by  establishing,  in  a manner  suited  to  his  existence,  his  relations 
with  the  beings  which  surround  him. 

The  functions  destined  to  the  preservation  of  the  species,  may 
likewise  be  divided  into  two  classes.  Those  of  the  first  class  re- 
quire the  concourse  of  two  sexes;  they  constitute  generation  pro- 
perly so  called;  those  of  the  second  order,  exclusively  belong  to 
the  female,  who,  after  conception,  is  alone  destined  to  bear,  to 
nourish,  to  bring  into  the  world,  and  suckle  the  new  being,  the 
result  of  conception. 

The  internal,  assimilating,  or  nutritive  functions  concur  in  the 
same  end,  and  all  serve  to  the  elaboration  of  the  nutritive  matter. 
The  aliment  once  admitted  into  the  body,  is  subjected  to  the  ac- 
tion of  the  digestive  organs,  which  separate  its  nutritive  parts: 
the  absorbents  take  it  up  and  convey  it  into  the  mass  of  fluids; 
the  circulatory  system  conveys  it  to  all  the  parts  of  the  body^ 
makes  it  flow  towards  the  organs;  the  lungs  and  the  secretory 
glands  supply  it  with  certain  elements,  and  deprive  it  of  others, 
alter,  modify,  and  animalize  it;  in  fine,  nutrition,  which  may  be 

K 


^74 


considered  as  the  complement  of  the  assimilating  functions, 
whose  object  it  is  to  provide  for  the  maintenance  and  growth  of 
the  organs,  applies  to  them  this  animalized  substance,  assimi- 
lated by  successive  acts,  when  ithas  become  quite  similar  to  them. 

Several,  however,  of  these  functions,  serve  at  once  to  preserve 
and  to  destroy.  Absorption,  which  takes  up  extraneous  mole- 
cules to  be  employed  in  the  growth  of  the  organs,  takes  up 
equally  the  organic  molecules  which  are  detached  by  motion, 
friction,  heat,  and  all  the  other  physical,  chemical,  and  vital 
causes.  The  action  of  the  heart  and  of  the  blood-vessels  sends 
these  fragments,  together  with  the  parts  truly  recrementitious,  to- 
wards the  lungs,  which,  at  the  same  time  that  they  bring  about 
a combination  of  the  nutritive  parts  with  the  oxygen  of  the  at- 
mosphere, separate  from  the  blood  the  materials  which  can  no 
longer  be  employed  in  nourishing  the  organs;  the  same  power 
sends  them  towards  the  secretory  glands,  which  not  only  purify 
what  is  liquid,  by  separating  from  it  that  which  cannot  without 
danger  remain  in  the  animal  econom)^  but  which  likewise  ela- 
borate or  prepare  peculiar  fluids,  some  of  which  are  results  of 
the  act  of  nutrition,  are  employed  in  that  act,  and  impart  to  the 
substances  on  which  it  is  performed  a certain  degree  of  animali- 
zation  (as  to  the  bile  and  saliva),  while  the  others  seem  to  be 
intermediate  states,  which  the  nutritive  particles  of  the  food 
are  obliged  to  undergo,  before  complete  animalization;  such 
are  the  serous  fluids  and  the  fat. 

It  might  perhaps  seem  more  in  conformity  to  the  order  of  na- 
ture, to  have  combined  the  account  of  respiration  with  that  of 
the  circulation,  by  treating  of  the  course  of  the  venous  blood, 
after  the  action  of  the  absorbent  vessels,  with  which  the  veins 
have  so  much  analogy:  then  to  have  treated  of  the  phenomena 
of  respiration,  or  of  the  conversion  of  the  venous  blood  into  ar- 
terial, and  of  the  course  of  the  latter  into  all  the  parts  of  the 
body,  by  the  action  of  the  heart  and  arteries.  But  the  advantage 
which  would  be  obtained  from  a method  so  contrary  to  the  com- 
mon practice,  which  is  to  consider  separately  the  functions  of 
circulation  and  respiration,  appeared  to  me  too  unimportant  to 
justify  its  adoption. 

The  external  or  relatiye  functions,  equally  connected  by  their 
common  destination,  connect  the  indiyidnal  to  every  thing  that 


75 


surrounds  him:  the  sensations,  by  warning  him  of  the  presence 
of  objects  which  may  be  useful  or  injurious  to  him;  motions,  by 
enabling  him  to  approach,  or  avoid  such  objects,  according  as  he 
perceives  relations  of  advantage  or  disadvantage,  according  as 
the  opposite  sensations  of  pain  or  pleasure  result  from  this  ac- 
tion on  them,  or  from  theirs  on  him.  In  fine,  voice  and  speech 
give  him  communication  with  beings  enjoying  the  same  means 
of  communication,  and  that  without  a necessity  of  motion.  The 
brain  is  the  principal  organ  of  these  functions,  as  the  system  of 
circulation  is  the  centre  of  the  assimilating  functions.  All  the 
impressions  received  by  the  organs  of  sense,  are  transmitted  to 
the  brain,  and  from  the  brain,  determinations  arise,  as  well  as 
the  voluntary  motions  and  the  voice.  The  sanguineous  system 
receives  the  molecules  destined  to  nutrition,  and  those  which 
are  to  be  thrown  out  of  the  body.  The  sensitive  and  circulatory 
systems  are  the  only  systems  provided  with  a centre,  (the  brain 
and  the  heart),  which  extend  to  all  parts  of  the  body,  by  emana- 
tions originating  from  that  organ,  or  terminating  in  it  (the 
nerves,  the  arteries,  and  veins):  and,  as  the  motions  and  the 
voice  depend  on  sensation,  and  are  immediately  connected  with 
it  as  necessary  consequences,  so  respiration,  secretion,  and  nutri- 
tion are,  in  a manner,  but  consequences  of  the  circulation  which 
distributes  the  blood  to  all  the  organs,  in  order  that  these  may 
produce  on  it  various  changes  which  constitute  respiration,  se- 
cretion, and  nutrition.  They  are,  to  anticipate  what  is  to  come 
hereafter,  only  different  kinds  of  secretion  that  take  place  at  the 
expense  of  the  different  principles  contained  in  the  blood. 

The  circulation  which  holds  the  functions  of  nutrition  in  a 
kind  of  dependence,  subjects  the  brain,  which  is  the  principal 
organ  of  the  external  functions,  to  an  influence  still  more  imme- 
diate and  indispensable.  The  muscular  motions  are  not  less  un- 
der its  influence.  It  is  the  first  function  that  is  apparent  in  the 
embryo,  whose  evolution  it  brings  about;  in  natural  death,  of 
all  the  functions,  it  is  the  last  to  cease.  These  are  many  reasons 
which  justify  Haller,  for  having  placed  it  in  the  first  order,  and 
for  having  begun  by  its  history,  his  great  work  on  physiology. 
I enter  into  this  digression,  only  to  expose  the  absurdity  of  the 
claims  of  some  authors,  who,  because  they  have  varied  the  me- 
thodical order  of  the  functions,  broken  the  series,  or  made  the 


76 


slightest  changes,  for  example,  by  placing  the  history  of  the 
fuiTction  of  smell  and  taste  before  the  account  of  the  internal  or 
nutritive  functions,  think  they  have  totally  changed  the  aspect 
of  the  science:  pitiful  sophists,  who  accumulate  subtleties  in- 
stead of  facts  and  ideas. 

In  warm  and  red-blooded  animals,  the  nutritive  functions, 
digestion,  absorption,  circulation,  respiration,  the  secretions 
and  digestion  are  performed  as  in  man,  and  in  that  respect, 
there  exist  between  them  very  slight  differences;  nay,  in  some 
animals,  these  functions  are  performed  with  much  more  energy. 
Thus  several  animals  digest  substances,  on  which  our  own  or- 
gans produce  no  effect,  and  others  (birds)  have  a more  rapid 
circulation,  a more  active  nutrition,  and  evolve  more  heat.  But 
not  one  of  them  is  as  well  provided  with  organs  to  keep  up  in- 
tercourse, as  a living  being,  with  surrounding  objects.  In  no  one 
animal,  are  the  senses  possessed  of  the  same  degree  of  perfec- 
tion; the  eagle,  whose  sight  is  so  piercing,  has  a ver)'  dull  sense 
of  touch,  taste,  and  smell.  The  dog,  whose  smell  is  exquisite, 
has  a very  ordinary  extent  of  sight;  in  him  the  taste  and  touch 
are  equally  imperfect. — His  touch,  in  the  perfection  of  which 
no  animal  comes  up  to  man,  has  not  been  improved  in  delicacy, 
at  the  expense  of  the  other  senses.  The  sight,  the  hearing,  the 
taste  and  smell,  preserve  a great  delicacy,  when  their  sensibility 
has  not  been  impaired,  by  injudicious  or  too  frequent  impres- 
sions. The  sensitive  centre  is  in  no  one  better  developed,  and 
fitter  to  direct  safely  the  use  of  the  organs  of  motion.  No  other 
animal  can  articulate  vocal  sounds,  so  as  to  acquire  speech. 

This  greater  extension  of  life  in  man,  from  the  number  and 
perfection  of  his  organs,  makes  him  liable  to  many  more  dis- 
eases than  the  other  animals.  It  is  with  the  human  body,  as  with 
those  machines  that  become  more  liable  to  be  deranged,  by  in- 
creasing the  number  of  their  wheels,  with  a view  of  obtaining 
more  extensive  or  more  varied  effects. 

All  i-rganized  bodies  are  possessed  of  assimilating  functions; 
but  as  assimilation  requires  means  varying  in  number  and  power, 
according  to  the  nature  of  the  being  which  performs  it,  the 
series  of  assimilating  phenomena  commences  in  the  plant  by 
absorption,  since  it  draws  immediately  from  the  earth,  the 
juices  which  it  is  to  appropriate  to  itself.  Its  absorbing  system, 


77 


at  the  same  time,  performs  the  functions  of  a circulatory  organ, 
or  rather,  the  circulation  does  not  exist  in  plants,  and  the  direct 
and  progressive  motion  of  the  sap  which  ascends  from  the  root 
towards  the  branches,  and  sometimes  in  a retrograde  course, 
from  the  branches  towards  the  roots,  cannot  be  compared  to 
the  circulation  of  the  fluids  which  takes  place  in  man,  and' in 
the  animals  which  most  resemble  him,  by  means  of  a system  of 
vessels  which  every  moment  bring  back  the  fluids  to  the  same 
spot,  and  convey  them  over  the  whole  body,  by  making  them 
describe  a complete  circle,  frequently,  even  a double  rotation 
(animals  with  a single  or  double  circulation,  that  is,  whose  heart 
has  one  or  two  ventricles.)  Plants  breathe  after  their  own  man- 
ner, and  produce  a change  in  the  atmospherical  air,  by  depriv- 
ing it  of  its  carbonic  acid  gas,  the  result  of  combustion  and  of 
animal  respiration,  so  that  by  a truly  admirable  reciprocity, 
plants,  which  decompose  carbonic  acid  and  allow  oxygen  to  ex- 
hale, continually  purify  the  air,  which  combustion  and  animal 
respiration  are  incessantly  contaminating. 

The  functions  preservative  of  the  species  are  common  to 
animals  and  plants.  The  organs  by  which  these  functions  are 
performed,  when  compared  in  these  two  kingdoms  of  nature, 
offer  a resemblance  which  has  struck  all  naturalists,  and  has  led 
them  to  observe,  that  of  all  the  acts  of  vegetable  life,  no  one  is 
more  analogous  to  the  animal  economy,  than  that  by  which 
fecundation  is  effected. 

We  shall  not  here  explain  the  general  characters  of  the  two 
orders  of  functions  which  are  subservient  to  the  preservation  of 
the  species:  the  differences  which  belong  to  them  are  pointed 
out  in  several  parts  of  this  work.*  I shall  merely  observe  with 
the  authors  who  have  considered  them  generally,  that  they  are 
in  an  inverse  ratio  to  each  other,  so  that,  in  proportion  as  the 
activity  of  the  assimilating  functions  increases,  that  of  the  ex- 
ternal functions  is  abated.  Grimaud  has,  in  the  most  complete 
manner,  illustrated  this  idea  of  the  constant  opposition  which 
exists  between  those  two  series  of  actions,  over  which,  in  the 
opinion  of  that  physician,  there  preside  two  powers  which  he 

• Especially  in  the  account  of  living'  beings,  § V.  of  the  preliminary  dis- 
course; articles  deep  and  fetus.  It  is  impossible  at  present  to  go  over  all  these 
'«listinctions,  without  entering  into  useless  and  disagreeable  repetitions. 


78 


calls  loco-motive  and  digestive.  It  is  in  no  kind  of  animals 
more  distinct  than  in  the  carnivorous,  which  possess  organs  of 
sense  of  the  greatest  delicacy,  together  with  muscles  capable  of 
prodigious  efforts,  and  yet  powers  of  assimilation  so  feeble, 
that  their  food  cannot  be  digested,  unless  it  be  composed  of 
material  analogous  in  composition  to  their  own  organs.* 

Too  much  importance  should  not  be  attached  to  this  classifi- 
cation; like  all  other  divisions,  it  is  purely  hypothetical.  All  is 
connected  together,  all  is  co-ordinate  in  the  animal  economy; 
the  functions  are  linked  together,  and  depend  on  one  another, 
and  are  performed  simulantaneously;  all  represent  a circle  of 
which  it  is  not  possible  to  mark  the  beginning  or  the  end.  In 
circulum  aheunt  (Hippocrates).  In  man,  while  awake,  diges- 
tion, absorption,  circulation,  respiration,  secretion,  nutrition, 
sensation,  motion,  voice,  and  even  generation,  may  be  perform- 
ed at  the  same  time;  but,  whoever  in  the  study  of  the  animal 
economy  should  bestow  his  attention  on  this  simulantaneous 
exertions  of  the  functions,  would  acquire  but  a very  confused 
knowledge  of  them.f 

By  becoming  familiar  with  these  abstractions,  one  might 
soon  mistake  them  for  realities;  one  might  even  go  the  length 
of  seeing  two  distinct  lives  in  the  same  individual;  one  would 

* In  carnivorous  animals,  the  power  of  dig-estion  is  extremely  weak;  but 
their  muscles  are  very  powerful.  This  relative  force  of  the  muscles  was  neces- 
sary in  carnivorous  animals,  as  they  live  by  depredations  and  slaughter,  as 
their  instinct,  in  unison  with  their  organization,  sets  them  constantly  at  war 
with  every  thing  that  has  life,  and  as  their  subsistence  depends  on  their  being 
victorious  in  the  battles  to  which  Nature  incessantly  calls  them. 

GRiMAUD,y?rst  JMemoir  on  Kutrition. 

f The  division  which  I lay  down,  is  not  to  be  strictly  adopted,  and  as 
being  absolutely  true.  It  is  a mere  hypothesis  to  be  attended  to,  only  in  so  far 
as  it  assists  in  arranging  one’s  ideas  in  a more  orderly  manner.  For,  every 
arrangement,  even  when  arbitrary,  is  useful  in  laying  before  us  a great 
number  of  ideas,  and  in  thereby  facilitating  the  comparison  that  is  to  be  insti- 
tuted among  them.  All  the  acts  of  Nature  are  so  connected,  and  are  linked 
together  in  so  close  an  union,  and  she  passes  from  the  one  to  the  other,  by 
such  uniform  motions,  and  by  gradations  so  insensible  and  so  adjusted,  as  to 
leave  no  space  for  us  to  lay  down  the  lines  of  separation,  or  demarcation, 
which  we  may  choose  to  draw.  All  our  methods  of  classing  and  arranging  the 
productions  of  nature,  are  mere  abstractions  of  the  mind,  which  does  not  con- 
sider things  as  they  really  are,  but  which  attends  to  certain  qualities,  and 
neglects  or  rejects  all  the  rest.  Grimaud,  Leetureson  Phjsioioj}-. 


79 


be  apt  to  assign  as  the  character  of  internal  life,  that  it  is  carried 
on  by  organs  independent  of  the  will.  Although  this  faculty  of 
the  soul  presides  over  the  phenomena  of  respiration,  of  masti- 
cation, of  the  expulsion  of  the  urine  and  faeces,  one  might  con- 
sider life  as  intrusted  to  unsymmetrical  organs,  although  the 
heart,  the  lungs, and  the  kidneys,  are  evidently  symmetrical;  one 
might  fancy  it  to  exist  in  the  foetus,  which  neither  breathes,  nor 
digests,  &c.  Nothing  in  the  animal  economy,  said  Galen,  is 
ruled  by  invariable  laws,  or  can  be  subject  to  the  same  accurate 
results  and  calculations,  as  an  inanimate  machine  (iV>7  est  in 
corpore  viventi  plane  sincerum.  Galen).  Thus,  respiration, 
which  connects  the  external  and  assimilating  functions,  fur- 
nishes the  blood  with  the  principle  which  is  to  keep  up  the 
action  of  the  brain,  and  to  excite  muscular  contractions. — On 
the  other  hand,  the  motion  of  the  muscles  is  of  use  in  the  dis- 
tribution of  the  humours,  and  concurs  in  the  phenomena  of 
assimilation.  The  brain,  by  means  of  the  eighth  pair  of  nerves, 
holds  influence  over  the  stomach.  The  sensations  of  taste  and 
smell  seem  to  preside,  in  an  especial  manner,  over  the  choice 
of  food  and  of  air,  and  to  belong  rather  to  the  digestive  and 
respiratory  functions,  than  to  those  of  the  intellect  or  of  thought. 

We  have  seen  in  this  kind  of  general  introduction  to  the 
study  of  physiology,  what  idea  is  to  be  formed  of  that  science 
as  well  as  of  life,  the  study  of  which  is  its  object;  into  how 
many  classes  the  beings  in  nature  may  be  divided,  and  into  how 
many  elements  they  are  resolvable:  what  differences  exist,  be- 
tween inorganized,  and  organized  and  living  bodies;  between 
plants  and  animals;  how  life  is  complicated,  modified,  and 
extended,  in  the  immense  series  of  beings  which  are  endowed 
with  it,  from  the  plant  to  man;  and  in  further  particularizing 
the  object  under  our  consideration,  we  have  examined,  what 
are  the  organs  which,  by  their  union,  form  the  human  machine; 
what  powers  govern  the  exercise  of  their  functions:  Then,  we 
have  laid  down  the  fundamental  laws  of  sensibility  and  contrac- 
tility, we  have  spoken  of  sympathies  and  habits,  of  the  internal 
nervous  apparatus,  which  unites,  collects,  and  systematizes  the 
organs  of  the  assimilating  functions;  we  have  endeavoured  to 
determine  from  facts,  the  existence  of  the  cause  which  subjects 
living  beings  to  a set  of  laws  very  different  from  those  which 


80 


inorganic  matter  obe3’s.  The  knowledge  of  these  laws,  is  the 
light  which  is  to  guide  us  in  the  a[)plication  to  physiology  of 
the  accessory  sciences.  Finally,  in  the  arrangement  of  the  ob- 
jects which  this  science  considers,  I have  adopted  a more  simple 
and  natural  division,  than  any  hitherto  employed. 

I shall  close  this  preliminary  discourse,  by  saying  a few  words 
on  the  order  adopted  in  the  distribution  of  the  chapters.  I might 
have  begun  by  a view  of  the  external  functions,  as  well  as  of 
those  of  assimilation  or  of  nutrition,  of  sensation,  or  of  diges- 
tion. I have  given  precedence  to  the  functions  of  assimilation, 
because  of  all  others,  they  are  the  most  essential  to  existence,  and 
their  exercise  is  never  interrupted,  from  the  instant  in  which  the 
embryo  begins  to  live,  till  death.  In  beginning  with  an  account 
of  them,  we  imitate  nature  therefore,  who  imparts  to  man 
this  mode  of  existence,  before  she  has  connected  him  with  out- 
ward objects,  and  who  does  not  deprive  him  of  it,  until  the 
organs  of  sense,  of  motion,  and  of  the  voice,  have  completely 
ceased  to  act. 

As  to  the  course  which  has  been  followed  in  the  arrangement 
of  the  functions  that  belong  to  the  same  order,  or  which  concur 
in  the  same  end,  it  was  too  well  laid  down  by  nature,  to  allow 
us  to  depart  from  it.  I have  thought  it  right,  that  the  conside- 
ration of  the  voice  should  immediately  precede  that  of  genera- 
tion, in  order  that  the  arrangement  might,  at  a glance,  shew  the 
connexion  which  exists  between  their  phenomena.  Several  ani- 
mals use  their  voice,  only  during  the  season  of  love;  the  birds 
which  sing  at  all  times,  have,  during  that  period,  a more 
powerful  and  sonorous  voice.  When  man  becomes  capable  of 
reproduction,  his  vocal  organs  suddenly^  become  evolved,  as 
though  nature  had  wished  to  inform  him,  that  it  is  through 
them  he  is  to  express  his  desires  to  the  gentle  being  who  may 
sympathize  in  them.  The  voice,  therefore,  serves  as  a natural 
connexion,  between  the  external  functions,  and  those  which  are 
employed  in  the  preservation  of  the  human  species. 

The  voice,  which  leads  so  naturally  from  the  functions  which 
establish  our  external  relations,  to  those  whose  end  is  the  pre- 
servation of  the  species,  is  still  more  intimately  connected  with 
motion.  It  is,  in  a manner,  the  complement  of  the  phenomena 
of  loco-motion;  by  means  of  it, our  communication  with  external 


81 


objects  is  rendered  easier,  more  prompt,  and  more  extensive:  it 
depends  on  muscular  action,  and  is  the  result  of  voluntary  mo- 
tion. Finally,  these  motions  sometimes  supply  the  place  of 
speech,  in  pantomime,  for  example,  and  in  the  greater  number 
of  cases,  the  language  of  action  concurs  in  adding  to  its  effect. 
Every  thing,  therefore,  justifies  me  in  placing  this  function 
after  motion,  in  separating  it  from  respiration,  with  which 
every  other  author  has  joined  it,  without  considering  that  the 
relation  between  the  voice  and  respiration  is  purely  anatomical, 
and  can,  therefore,  in  no  wise  apply  to  physiology. 

I have  placed  after  generation,  an  abridged  account  of  life 
and  death,  in  which  will  be  found  whatever  did  not  belong  to 
any  of  the  preceding  divisions.  The  necessity  of  this  appendix, 
containing  the  history  of  the  different  periods  of  life,  that  of  the 
temperaments  and  varieties  of  the  human  species,  that  of  death 
and  putrefaction,  arises  from  the  impossibility  of  introducing 
into  the  particular  history  of  the  functions,  these  general  phe- 
nomena in  which  they  all  participate. 


I. 


FIRST  CLASS. 


LIFE  OF  THE  INDIVIDUAL. 


FIRST  ORDER. 


FUNCTIONS  OF  ASSIMILATION, 

Or,  Functions  which  are  subservient  to  the  preservation 
of  the  Individual^  by  assimilating  to  his  substance 
the  food  by  which  he  is  nourished. 


ir 


: 


VY-Jv'. 

" • . ■ "■■'  ' • -I 


' -:p€r 


NEW  ELEMENTS 


OF 

PHYSIOLOGY. 


CHAPTER  I. 

OF  DIGESTION, 

I.  Digestion  is  a function  common  to  all  animals,  by  which 
substances  extraneous  to  them,  are  introduced  into  their  bodies, 
and  subjected  to  the  action  of  a peculiar  system  of  organs,  their 
qualities  altered,  and  a new  compound  formed,  fitted  to  their 
nourishment  and  growth. 

II.  General  considerations  on  the  I^igestive  Organs,  Animals 
alone  are  provided  with  organs  of  digestion;  all  of  them,  from 
man  down  to  the  polypus,  contain  an  alimentary  cavity  variously 
shaped.  The  existence  of  a digestive  apparatus  may,  therefore, 
be  taken  as  the  essential  characteristic  of  the  animal  kind.  In 
man,  this  apparatus  consists  of  a long  tube  extending  from  the 
mouth  to  the  anus:  within  this  canal,  there  empty  themselves 
the  excretory  ducts  of  several  neighbouring  glands,  that  secrete 
fluids  fit  for  changii^,  for  liquefying,  and  animalizing  the  ali- 
mentary substance.  The  different  parts  of  this  digestive  tube  are 
not  of  equal  capacity;  at  first,  enlarged  in  the  part  which  forms 
the  mouth  and  pharynx,  it  becomes  narrower  in  the  oesophagus; 
this  last,  dilating  considerably,  forms  the  stomach,  which  again 
contracting,  is  continued  down  under  the  name  of  intestine. 
This  tube  itself  varies  in  size  in  different  parts  of  its  extent; 
and  it  is  by  the  consideration  of  these  differences  of  size,  that 
anatomists  have  principally  been  guided  in  their  divisions. 

The  length  of  the  digestive  tube  is  from  five  to  six  times  the 
length  of  the  whole  body,  in  an  adult:  it  is  greater  in  proportion 


OF  DIGESTION. 


86 

in  a child.  At  this  age,  likewise,  digestion  is  more  active,  and 
proportioned  to  the  necessities  of  growth  in  the  individual.  The 
digestive  cavity  is  in  man  open  at  both  extremities;  in  some 
animals,  in  the  zoophyte  for  example,  one  opening  serves  the 
purpose  of  mouth  and  of  anus,  receives  the  food  and  ejects  the 
excrementitious  remains. 

The  extent  of  the  digestive  canal  is  according  to  the  nature 
of  the  aliments  on  which  the  animals  feed:  the  less  those  ali- 
ments are  analogous  in  their  nature,  to  the  substance  of  the 
animal  which  they  are  to  nourish,  the  longer  must  they  remain 
in  his  body  to  undergo  the  necessary  changes.  Therefore,  it  is 
observed,  that  the  intestine  of  graminivorous  animals  is  very 
long,  their  stomach  very  capacious  and  often  complex,  while 
carnivorous  animals  have  their  intestinal  canal  short  and  strait, 
and  so  arranged,  that  the  animal  substances  which  are  most 
nourishing,  in  least  bulk,  of  easy  and  rapid  digestion,  which,  by 
too  long  a stay  in  the  intestines,  might  become  putrid,  pass 
readily  through  it.  In  this  respect,  man  holds  a middle  station 
between  those  animals  which  feed  on  vegetables,  and  those 
which  feed  on  animal  substances.  He  is,  therefore,  equally  fitted 
for  these  two  kinds  of  food;  he  is  neither  exclusively  herbivor- 
ous, nor  carnivorous,  but  omnivorous  or  polyphagous.  This 
question,  of  such  easy  solution,  has  long  employed  physicians, 
naturalists,  and  philosophers;  each  bringing,  in  favour  of  his 
opinion,  very  plausible  arguments,  drawn  from  the  form  and 
number  of  the  teeth,  from  the  length  of  the  intestinal  canal, 
from  the  force  of  its  parietes,  &c. 

The  parietes  of  the  digestive  tube  are  essentially  muscular;  a 
mucous  membrane  lines  its  inside,  forming  within  it  various 
folds;  lastly,  a third  coat  is  accidentally  placed  over  the  other 
two:  and  is  furnished  by  the  pleura  to  the  oesophagus,  by  the 
peritoneum  to  the  stomach,  as  well  as  to  the  intestinal  canal. 

The  characteristic  of  this  third  coat  is,  that  it  does  not  cover 
the  whole  surface  of  the  parts  of  the  tube  to  which  it  is  applied. 
The  muscular  coat  may  be  considered  as  a long  hollow  muscle, 
extending  from  the  mouth  to  the  anus,  and  formed,  throughout 
almost  the  whole  of  its  length,  by  two  layers  of  fibres,  the  one 
set  longitudinal,  the  other  circular.  The  will  directs  the  motions 
of  the  two  extremities,  while  the  rest  of  its  course  is  not  under 


OF  DIGESTION.  gy 

its  control.  In  the  cells  of  the  tissue  which  unites  its  surfaces 
to  the  other  coats,  fat  never  accumulates,  which  might  have 
impeded  its  contractions,  and  straitened  and  even  obliterated 
the  tube  along  which  the  food  was  to  pass. 

III.  Of  Food,  solid  and  liquid.  The  aliments  which  nourish 
man,  are  obtained  from  vegetables  or  from  animals.  The  mineral 
kingdom  furnishes  only  condiments,  medicinal  substances  or 
poisons. 

By  aliment  is  meant  whatever  substance  affords  nutrition,  or 
whatever  is  capable  of  being  acted  upon  by  the  organs  of  diges- 
tion. Substances  which  resist  the  digestive  action,  those  which 
the  gastric  juice  cannot  sheathe,  whose  asperities  it  cannot 
soften  down,  whose  nature  it  cannot  change,  possess,  to  a certain 
degree,  the  power  of  disturbing  the  action  of  the  digestive  tube, 
which  revolts  from  whatever  it  cannot  overcome:  there  is  no 
essential  difference  between  a medicinal  substance  and  a poison. 
Our  most  active  remedies  are  obtained  from  among  the  poison- 
ous substances:  tartar  emetic,  corrosive  sublimate,  opium,  all 
of  them  remedies  of  so  much  efficacy  in  skilful  hands,  when 
administered  unseasonably  or  in  too  strong  doses,  act  as  most 
violent  poisons;  they  forcibly  resist  the  digestive  powers  and 
furnish  them  nothing  to  be  acted  upon,  while  mild  and  inert  sub- 
stances yield  to  these  powers,  and  come  under  the  class  of  ali- 
ments. What  then  is  to  be  thought  of  our  ptisans,  of  chicken 
and  veal  broth,  and  other  such  remedies?  That  they  are  employ- 
ed to  deceive  the  hanger  and  thirst  of  the  patient,  to  prevent  his 
receiving  into  his  stomach,  substances  whose  laborious  diges- 
tion would  take  up  the  strength  required  for  the  cure  of  the  dis- 
ease; that  they  are  mere  precautions  of  regimen;  that  he  who 
most  varies  this  kind  of  resource,  can  only  be  said  to  adopt  a 
treatment  of  expectation,  leaving  to  nature  alone,  the  care  of  ex- 
citing those  salutary  motions  which  are  to  bring  about  a cure. 
Why  do  certain  vegetable  purgatives,  as  manna  and  tamarinds, 
produce  so  little  effect,  even  though  given  in  large  doses?  Be- 
cause these  substances  contain  many  nutritious  particles  capable 
of  being  assimilated,  so  that  strong  constitutions  digest  them 
and  completely  neutralize  their  irritating  or  purgative  qualities. 
An  animal  or  vegetable  substance,  though  essentially  nutritious, 
may  act  as  a medicine,  or  even  as  a poison,  when,  in  consequence 


OF  DIGESTION. 


88 

of  the  extreme  debility  of  the  digestive  tube,  or  because  it  has 
not  been  sufficiently  divided  by  the  organs  of  mastication,  it  re- 
sists the  digestive  action.  Thus  surfeits  are  brought  on,  because 
the  stomach  is  debilitated,  because  it  is  oppressed  by  too  great 
a mass  of  substances,  or  because  having  been  imperfectly  tritu- 
rated, they  are  insoluble.  It  is  on  considerations  of  this  kind, 
that  the  true  foundations  of  materia  raedica  are  laid. 

Mineral  substances  are  of  a nature  too  heterogeneous  to  our 
own,  to  admit  of  being  converted  into  our  substance.  It  appears 
that  their  elements  require  the  elaboration  of  vegetable  life; 
hence  it  has  been  justly  observed,  that  plants  are  laboratories 
in  which  nature  prepares  the  food  of  animals. 

Aliments  obtained  from  plants  are  less  nutritious  than  those 
furnished  by  the  animal  kingdom,  because  in  a given  bulk,  they 
contain  fewer  parts  that  can  be  assimilated  to  our  own  substance. 
Of  all  the  parts  of  vegetables,  the  most  nourishing  is  their  amy- 
laceous fecula,  but  it  yields  the  more  readily  to  the  action  of 
the  digestive  organs,  from  having  already  experienced  an  inci- 
pient fermentation;  on  that  account,  leavened  bread  is  the  best 
of  vegetable  aliments.  The  flesh  of  young  animals  is  less  nou- 
rishing than  that  of  the  full-grown,  although,  at  an  early  age, 
the  flesh  of  the  former  abounds  more  in  gelatinous  juices;  for, 
this  abundant  gelatine  wants  the  necessary  degree  of  consistence. 

However  various  our  aliments  may  be,  the  action  of  our  or- 
gans always  separates  from  them  the  same  nutritious  principles; 
in  fact,  whether  we  live  exclusively  on  animal  or  vegetable  sub- 
stances, the  internal  composition  of  our  organs  does  not  alter; 
an  evident  proof,  that  the  substance  which  we  obtain  from  ali- 
ments, to  incorporate  with  our  own,  is  always  the  same,  and 
this  affords  an  explanation  of  a saying  of  the  father  of  physic. 
“ There  is  but  one  food,  but  there  exist  several  forms  of  food.” 

Attempts  have  been  made  to  ascertain  the  nature  of  this  ali- 
mentary principle,  common  to  all  nutritive  substances,  and  it  is 
conjectured,  with  some  probability,  that  it  must  be  analogous 
to  gummy,  mucilaginous,  or  saccharine  substances;  they  are  all 
formed  from  hydrogen  and  carbon,  are  well  known  to  differ 
chemically,  only  in  the  different  proportions  of  oxygen  which 
they  contain.  Thus,  sugar  is  a kind  of  gum,  containing  a con- 
siderable quantity  of  oxygen;  and  which  is  reduced,  in  a cer- 


89 


OF  DIGESTION. 

tain  degree,  to  the  state  of  starch,  when  brought  to  a very  fine 
powder  by  means  of  a rasp,  for,  the  friction  disengaging  a por- 
tion of  its  oxygen,  deprives  it  in  part  of  its  flavour,  and  leaves  it 
an  insipid  taste,  similar  to  that  of  farinaceous  substances.  No- 
thing, in  fact,  nourishes  better,  more  quickly,  and  from  a smaller 
bulk,  than  substances  of  this  kind.  The  Arab  crosses  the  vast 
plains  of  the  desert,  and  supports  himself  by  swallowing  a 
small  quantity  of  gum  arabic.  The  nourishing  quality  of  animal 
and  vegetable'  jellies  is  well  known;  saccharine  substances  soon 
cloy  the  appetite  of  those  who  are  fondest  of  them.  In  decrepid 
old  age,  some  persons  live  exclusively  on  sugar;  I know  several 
in  that  condition,  who  spend  the  day  in  chewing  this  substance, 
which  is  a laborious  employment  for  their  feeble  and  toothless 
jaws.  Lastly,  milk,  the  sole  nourishment  of  the  early  periods  of 
life,  contains  a great  proportion  of  gelatinous  and  saccharine 
matter. 

Though  man,  destined  to  live  in  all  latitudes,  is  formed  to 
subsist  on  all  kinds  of  food,  it  has  been  observed,  that  the  in- 
habitants of  warm  climates  generally  prefer  a vegetable  diet. 
The  Bramins  in  India,  the  inhabitants  of  the  Canary  Islands, 
and  of  the  Brazils,  &c.  who  live  almost  exclusively  on  herbs, 
grain,  and  roots,  inhabit  a climate,  against  the  excessive  heat  of 
which  they  have  to  seek  means  of  protection:  now,  the  digestion 
of  vegetables  is  attended  with  less  heat  and  irritation.  The 
philosophical  or  religious  sects,  by  which  abstinence  from  ani- 
mal food  was  considered  as  a meritorious  act,  were  all  insti- 
tuted in  warm  climates.  The  school  of  Pythagoras  flourished  in 
Greece,  and  the  anchorites,  who,  in  the  beginning  of  the  Chris- 
tian religion,  peopled  the  solitudes  of  Thebais,  could  not  have 
endured  such  long  fastings,  or  supported  themselves  on  dates 
and  water,  in  a more  severe  climate.  So  that  the  monks  that 
removed  into  different  parts  of  Europe,  were  obliged  to  relax 
from  the  excessive  severity  of  such  a regimen,  and  yielded  to 
the  irresistible  influence  of  the  climate;  the  most  austere  came 
to  add  to  the  vegetables,  which  formed  the  base  of  their  food, 
eggs,  butter,  fish,  and  even  water  fowl.  In  books  of  casuistry, 
it  may  be  seen,  on  what  ridiculous  grounds  there  was  granted  a 
dispensation  in  favour  of  plovers,  of  water  hens,  wild  ducks, 
snipes,  scoters,  birds  whose  brown  flesh,  more  animalized  and 

M 


90 


OF  DKiESTlOK. 


more  heating,  ought  to  have  been  proscribed  from  the  kitchen 
of  monasteries,  much  more  strictly  than  that  of  common  poultry. 

Consider  what  is  the  alimentary  regimen  of  the  different  na- 
tions on  the  face  of  the  earth,  and  you  will  see,  that  a vegetable 
diet  is  preferred  by  the  inhabitants  of  warm  countries:  to  them, 
sobriety  is  an  easy  virtue;  it  is  a happy  consequence  of  the  cli- 
mate. Northern  nations,  on  the  contrary,  are  voracious  from 
instinct  and  necessity.  They  swallow  enormous  quantities  of 
food,  and  prefer  those  substances  which  in  digestion  produce 
the  most  heat.  Obliged  to  struggle  incessantly  against  the  action 
of  cold,  which  tends  to  benumb  the  vital  powers,  to  suspend 
every  organic  motion,  their  life  is  but  a continual  act  of  resist- 
ance to  external  influences.  Let  us  not  reproach  them  with 
their  voracity,  and  their  avidity  for  ardent  spirits  and  fermented 
liquors.  Those  nations  that  inhabit  the  confines  of  the  habitable 
world,  in  which  man  is  scarcely  able  to  withstand  the  severity 
of  the  climate,  the  inhabitants  of  Kamtschatka,  the  Samoiedes, 
live  on  fish,  that  in  the  heaps  in  which  they  are  piled  up,  have 
already  undergone  a certain  degree  of  putrefactive  fermentation. 
Does  not  the  use  of  a food  so  acrid  and  heating,  that  in  our 
climate  it  would  inevitably  be  attended  with  a febrile  action, 
prove  plainly  the  necessity  of  balancing,  by  a vigorous  inward 
excitement,  the  debilitating  influence  of  powers  that  are  ope- 
rating from  without?  The  abuse  of  spirituous  liquors  is  fatal  to 
the  European  transported  to  the  burning  climate  of  the  West 
Indies.  The  Russian  drinks  spirituous  liquors  with  a sort  of  im- 
punity, and  lives  on  to  an  advanced  age,  amidst  excesses  under 
which  an  inhabitant  of  the  south  of  Europe  would  sink. 

Th  is  influence  of  climate  affects  alike  the  regimen  of  man  in 
health,  and  that  of  man  in  sickness,  and,  it  has  been  justly  ob- 
served of  medicine,  that  it  ought  to  vary  according  to  the  places 
in  which  it  is  practised.  Barley  ptisan,  honey,  and  a few  other 
substances,  the  greater  part  obtained  from  the  vegetable  king- 
dom, sufficed  to  Hippocrates  in  the  treatment  of  diseases;  his 
therapeutic  treatment  was,  in  almost  every  case,  soothing  and 
refreshing.  Physicians,  who  practise  in  a climate  such  as  that  of 
Greece,  may  imitate  this  simplicity  of  the  father  of  physic. 
Opium,  bark,  wine,  spirits,  aromatics,  and  the  most  active  cor- 
dials are,  on  the  other  hand,  the  medicines  suited  to  the  inhabi- 


OF  DIGESTION. 


91 

tants  of  the  north.  The  English  physicians  use,  freely  and  with- 
out risk,  these  medicines,  which  elsewhere  would  be  attended 
with  the  utmost  danger. 

Simple  aqueous  drinks  promote  digestion,  by  facilitating  the 
solution  of  the  solids;  by  serving  as  a vehicle  to  their  divided 
parts;  and  when  rendered  active  by  saline  or  other  substances, 
as  spirituous  liquors  are  by  alcohol,  they  are  further  useful  in 
stimulating  the  organs  and  exciting  their  action. 

The  least  compound  drinks  are  possessed,  in  different  de- 
grees, of  this  double  property  of  dissolving  solid  aliments,  and 
of  stimulating  the  digestive  organs.  The  purest  water  is  render- 
ed stimulating  by  the  air,  and  by  the  salts  which  it  contains,  in 
different  proportions;  and,  to  the  want  of  that  stimulating  qua- 
lity, is  to  be  attributed  the  difficult  digestion  of  distilled  water. 

The  drinks  best  suited  to  the  wants  of  the  animal  economy, 
are  those  in  which  the  stimulating  principles  are  blended,  in 
due  proportions,  with  the  water  which  holds  them  in  solution. 
But  almost  all  the  fluids  which  we  drink,  contain  a certain  pro- 
portion of  nutritious  particles.  Wine,  for  example,  contains 
these  nutritive  particles  in  greater  quantity,  as  it  is  the  produce 
of  a warmer  climate,  and  as  saccharine  matter  predominates  in 
its  composition.  Thus,  Spanish  wines  are  in  themselves  nou- 
rishing, and  are  perhaps  fitter  to  satisfy  hunger  than  to  allay 
thirst,  while  the  acidulous  Rhenish  wines,  which  are  merely 
thirst-allaying,  scarcely  contain  any  cordial  quality.  Between 
the  two  extremes  are  the  French  wines,  which  possess,  in  a 
nearly  equal  degree,  the  treble  advantage  of  diluting  the  fluids, 
of  stimulating  the  organs,  and  of  furnishing  to  the  animal  eco- 
nomy materials  of  nutrition. 

IV.  Of  hunger  and  thirst.  By  the  words  hunger  and  thirsty 
are  meant  two  sensations,  which  warn  us  of  the  necessity 
of  repairing  the  loss  which  our  body  is  continually  undergoing 
from  the  action  of  the  vital  principle.  Their  nature,  as  is  well 
observed  by  M.  Gall,  is  not  better  known  than  that  of  thought. 
Let  us  endeavour  to  explain  the  phenomena  by  which  they  are 
attended. 

The  effects  of  a protracted  abstinence  are,  a diminution  of  the 
weight  of  the  body,  a diminution  which  becomes  sensible  In  the 
course  of  twenty-four  hours;  a wasting  of  the  body,  from  the  loss 


92 


OF  DIGESTION. 


of  fat,  discoloration  of  the  fluids,  especially  the  blood,  loss  of 
strength,  excessive  sensibility,  sleeplessness,  with  painful  sensa- 
tions in  the  epigastric  region. 

Death  from  inanition  is  most  easily  brought  on,  in  those  who 
are  young  and  robust.  Thus,  the  unfortunate  father  whose  hor- 
rible story  has  been  related  by  Dante,  condemned  to  die  of  hunger 
and  shut  up  with  his  children  in  a dark  dungeon,  died  the  last, 
on  the  eighth  day,  after  having  witnessed,  in  the  convulsions  of 
rage  and  despair,  the  death  of  his  four  sons,  unhappy  victims  of 
the  most  execrable  vengeance  ever  recorded  in  the  history  of 
man.  Haller  has  related,  in  his  great  work  on  physiology,  se- 
veral instances  of  prolonged  abstinence;  if  we  are  to  give  credit 
to  these  accounts,  some  of  which  are  deficient  in  the  degree  of 
authenticity  required  to  warrant  belief,  persons  have  been  known 
to  pass  eighteen  months,  two,  three,  four,  five,  six,  seven,  and 
even  ten  years,  without  taking  any  nourishment.  In  the  memoirs 
of  the  Edinburgh  Society,  is  found  the  history  of  a woman  who 
lived  on  whey  only,  for  fifty  years.  The  subjects  of  these  cases 
are  mostly  weak,  infirm  women,  living  in  obscurity  and  inaction, 
and  in  whom  life,  nearly  extinct,  just  showed  itself,  in  an  almost 
insensible  pulse,  an  unfrequent  and  indistinct  respiration.  It  is  a 
fact  well  worthy  of  observation,  that  the  muscles  and  viscera  of 
some  of  them  when  examined  after  death,  shone  with  a light 
evidently  phosphoric.^  Can  it  be  that  phosphorus  is  the  result 
of  the  lowest  degree  of  animalization?  It  may  be  easily  con- 
ceived that  living,  in  a manner,  on  their  own  substance,  the  fluids 
in  such  persons,  have  been  frequently  subjected  to  the  causes 
which  produce  assimilation  and  animalization,  and  have  under- 
gone the  greatest  alteration  of  which  they  are  capable. 

The  proximate  cause  of  hunger  has  by  some  been  conceived 
to  depend  on  the  friction  of  the  nervous  papillae  of  the  empty 
stomach  on  each  other;  by  others,  it  has  been  imputed  to  the 
irritation  produced  on  its  parietes,  by  the  accumulation  of  the 
gastric  juice.  It  has  been  thought  to  depend  on  the  lassitude  at- 
tending the  permanent  contraction  of  the  muscular  fibres  of  the 
stomach;  and  on  the  compression  and  creasing  of  the  nerves, 

* Nitidissima  viscera  sunt  animali mn  farne  enectorum,  et  argentei fibrarunifasdcul’ 

Haller,  Eiem,  Phys.  tom.  VI. page  183. 


OF  niORSTION. 


93 

during-  that  permanent  constriction j on  the  dragging  down  of 
the  diaphragm  by  the  liver  and  spleen,  when  the  stomach  and  in- 
testines being  empty,  cease  to  support  those  viscera:  a dragging 
’ which  is  the  greater,  as  a new  mode  of  circulation  takes  place 
in  the  viscera,  which  are  supplied  with  blood  by  the  cceliac  ar- 
tery, and  while  the  stomach  receives  less  blood,  the  spleen  and 
liver  increase  in  weight  and  size,  because  their  supply  is  in- 
creased. 

Those  who  maintain,  that  hunger  depends  on  the  friction  of 
the  parietes  of  the  stomach  against  each  other,  when  brought 
together  in  an  empty  state,  adduce  the  example  of  serpents, 
whose  stomach  is  purely  membranous,  and  who  endure  hunger 
a long  time,  while  fowls  whose  powerful  and  muscular  stomach 
is  able  to  contract  stongly  on  itself,  endure  it  with  difficulty.  But 
to  say  nothing  of  the  great  difference  of  vitality,  in  the  organs  of  a 
bird  and  of  a reptile,  the  stomach  which  continues  closing  on  itself 
as  it  is  emptied,  may  contract  to  such  a degree  as  scarcely  to 
equal  in  size  a small  intestine,  without  its  following,  as  a neces- 
sary consequence,  that  the  parietes  which  are  in  contact,  should 
exert  on  each  other  any  friction,  on  which  the  sensation  of  hun- 
ger may  depend.  In  fact,  the  presence  of  food  is  necessary  to 
determine  an  action  of  the  parietes  of  the  stomach,  and  as  long 
as  it  is  empty,  there  is  nothing  to  call  forth  such  action. 

Those  who  think  that  hunger  is  mechanically  produced  by  the 
weight  of  the  spleen  and  liver  that  keeps  pulling  down  the  dia- 
phragm, which  the  empty  stomach  no  longer  bears  up,  observe, 
that  it  may  be  appeased,  for  a time,  by  supporting  the  abdominal 
viscera  by  means  of  a wide  girdle;  that  hunger  ceases  as  soon  as 
the  stomach  is  full,  before  the  food  can  have  yielded  to  it  any 
materials  of  nutrition.  On  this  hypothesis,  which  is  purely  me- 
chanical, as  that  which  explains  hunger  by  the  irritation  of  the 
gastric  juice,  by  the  lassitude  of  the  contracted  muscles,  by  the 
compression  of  the  nerves,  how  shall  we  explain  the  fact,  that 
when  the  hour  of  a meal  is  over,  hunger  ceases  for  a time?  Ought 
not  hunger,  on  the  contrary,  to  be  considered  as  a nervous  sen- 
sation which  exists  in  the  stomach,  is  communicated  by  sympa- 
thy to  all  the  other  parts,  and  keeping  up  an  active  and  con- 
tinuous excitement  in  the  organ  in  which  it  is  principally  seated, 
determines  into  it  the  fluids  from  all  parts.  This  phenomenon, 


OF  DIGESTION. 


94 

like  all  those  which  depend  on  nervous  influence,  is  governed  by 
the  laws  of  habit,  by  the  influence  of  sleep,  and  of  the  passions 
of  the  mind,  whose  power  is  so  great,  that  literary  men,  ab- 
sorbed in  meditation  and  thought,  have  been  known  entirely  to 
forget  that  they  required  food.  Every  thing  which  awakens  the 
sensibility  of  the  stomach,  in  a direct  or  sympathetic  manner,  in- 
creases the  appetite  and  occasions  hunger.  Thus,  bulimia  de- 
pends, sometimes,  on  the  irritation  of  a tape  worm  in  the  organs 
of  digestion.  The  application  of  cold  to  the  skin,  by  increasing, 
from  sympathy,  the  action  of  the  stomach,  has  been  known  to 
occasion  fames  canina^  of  which  several  instances  are  related  by 
Plutarch  (Life  of  Brutus).  Ardent  spirits,  and  highly  seasoned 
food,  excite  the  appetite,  even  when  the  stomach  is  overfilled. 
Whatever,  on  the  contrary,  blunts  or  renders  less  acute  the  sen- 
sibility of  the  stomach,  renders  more  endurable  or  suspends  the 
sensation  of  hunger.  Thus,  we  are  told  by  travellers,  that  the 
Turkish  dervises  and  the  Indian  faquirs,  endure  long  fasts,  be- 
cause they  are  in  the  habit  of  using  opium,  and  lull,  in  a manner, 
by  this  narcotic,  the  sensibility  of  the  stomach.  Tepid  and  re- 
laxing drinks  Impair  the  appetite;  the  use  of  opiates  suspends 
suddenly  the  action  of  the  stomach. 

V.  Of  thirst.  The  blood  deprived  of  its  serosity,  by  insensi- 
ble perspiration  and  by  internal  exhalation,  requires  incessant 
dilution,  by  the  admixture  of  aqueous  parts,  to  lessen  its  acri- 
mony; and  as  the  serosity  is  incessantly  exhausting  itself,  tfie 
necessity  for  repairing  that  loss  is  ever  urgent.  The  calls  of 
thirst  are  still  more  absolute  than  those  of  hunger,  and  it  is  much 
less  patiently  endured.  If  it  be  not  satisfied,  the  blood,  and  the 
fluids  which  are  formed  from  it,  become  more  and  more  stimu- 
lating, from  the  concentration  of  the  saline  and  other  substances 
which  they  contain.  The  general  irritation  gives  rise  to  an  acute 
fever,  with  heat  and  parching  of  the  fauces,  which  inflame  and 
may  even  become  gangrenous,  as  happens  in  some  cases  of  hy- 
drophobia. English  sailors,  who  were  becalmed,  had  exhausted 
all  their  stock  of  fresh  water,  and  were  at  a distance  from  land; 
not  a drop  of  rain  had  for  a long  while  cooled  the  atmosphere: 
after  having  borne,  for  some  time,  the  agonies  of  thirst,  further 
increased  by  the  use  of  salt  provisions,  they  resolved  to  drink 
their  own  urine.  This  fluid,  though  very  disgusting,  allayed 


OP  DIGESTION. 


95 


their  thirst;  but  at  the  end  of  a few  days,  it  became  so  thick  and 
acrid,  that  they  were  incapable  of  swallowing  a mouthful  of  it. 
Reduced  to  despair,  they  expected  a speedy  death,  when  they 
fell  in  with  a ship  which  restored  them  to  hope  and  life.  Thirst 
is  increased  every  time  that  the  aqueous  secretions  are  increased; 
thus,  it  becomes  distressing  to  a dropsical  patient,  in  whom  the 
fluids  are  determined  towards  the  seat  of  effusion.  It  is  exces- 
sive in  diabetes,  and  in  proportion  to  the  increased  quantity  of 
urine.  In  fever,  it  is  increased,  from  the  effect  of  perspiration, 
or  because  in  some  of  these  affections,  for  example,  in  bilious 
fevers,  the  blood  seems  to  become  more  acrid.  Hence  the  ad- 
vantage of  cooling,  diluting,  and  refreshing  drinks,  administered 
copiously,  with  a view  to  correct  the  temporary  acrimony  occa- 
sioned by  the  absence  of  a great  quantity  of  the  serous  parts  of 
the  blood,  and  to  lessen  the  over  excitement  of  a fluid  become 
too  stimulating. 

The  use  of  aqueous  drink  is  not  the  most  effectual  method  of 
allajdng  thirst.  A traveller  exposed  to  the  scorching  heat  of  sum- 
mer, finds  it  advantageous  to  mix  spirits  to  plain  water,  which 
alone  does  not  stimulate  sufficiently  the  mucous  and  salivary 
glands,  whose  secretion  moistens  the  inside  of  the  mouth  and 
pharynx,  and  covers  these  surfaces  with  the  substance  best  cal- 
culated to  suspend,  at  least  for  a time,  the  erethism  on  which 
thirst  appears  to  depend. 

VI.  On  mastication.  The  organs  employed  in  the  mastication  of 
the  food,  are  the  lips,  the  jaws,  and  the  teeth  with  which  these 
are  furnished:  the  muscles  by  which  they  are  moved,  and  those 
which  form  the  parietes  of  the  mouth.  The  motions  of  the  lips 
are  extremely  varied,  and  depend  on  the  single  or  combined 
action  of  their  muscles,  by  which  the  greater  part  of  the  face  is 
covered,  and  which  may  be  enumerated  as  follow: — Elevators 
of  the  upper  lip  {caninus^  incisivus,  levatores  communes  labiorum 
and  myrtiformes).  Depressors  of  the  under  lip  (triangularis 
labiorum^  quadratus  gence).  Abductors  (buccinator, zygomaticus 
major  and  minor,  platysma  myoides,')  Constrictors  (orbicularis 
oris'). 

VII.  The  motions  of  the  upper  jaw  are  so  confined,  that  some 
have  denied  that  it  has  any  motion;  it  nevertheless  rises  a little, 
when  the  lower  jaw  descends;  but  it  ie  principally  by  the  de- 


96 


OF  DIGESTION. 


pression  of  the  latter,  and  that  the  mouth  is  opened.  The  mus- 
cles at  the  back  of  the  neck,  and  that  part  of  the  digastric  mus- 
cle nearest  the  mastoid  process,  produce  a slight  elevation  of 
the  upper  jaw,  which  moves  with  the  whole  head,  to  the  bones 
of  which  it  is  firmly  united.  This  connexion  of  the  upper  jaw 
with  the  bones  of  the  head,  renders  this  jaw  less  moveable  in 
man  than  in  the  great  number  of  animals,  in  which,  freed  from 
the  enormous  weight  of  the  skull,  it  stretches  out  in  front  of 
that  cavity,  over  the  lower  jaw.  As  we  follow  downwards  the 
scale  of  animal  existence,  the  motions  of  the  upper  jaw  is  seen 
to  increase,  the  further  we  descend  from  the  human  species;  it 
is  equal  to  that  of  the  lower  jaw,  in  the  reptiles  and  in  several 
fishes;  hence  the  enormous  dimensions  of  the  mouth  of  the 
crocodile  and  shark;  hence  serpents  frequently  swallow  a prey 
of  a bulk  greater  than  their  own,  and  would  be  suffocated,  but 
for  the  power  they  possess  of  suspending  respiration  for  a long 
time,  and  of  waiting  patiently  till  the  gastric  juice  dissolves  the 
food,  as  it  is  swallowed. 

In  the  act  of  mastication,  the  upper  jaw  may  be  considered 
as  an  anvil,  on  which  the  lower  jaw  strikes  as  a moveable  ham- 
mer, and  the  motions  of  the  under  jaw,  the  pressure  it  exerts, 
and  its  efforts,  would  soon  have  disturbed  the  connexion  of  the 
different  bones  of  which  the  face  is  formed,  if  this  unsteady 
edifice,  merely  formed  of  bones,  in  juxta  position,  or  united  by 
sutures,  were  not  supported,  and  did  not  transmit  to  the  skull, 
the  double  effort  which  presses  on  it  from  below  upwards,  and 
pushes  it  out  laterally.  Six  vertical  columns,  the  ascending 
apophyses  of  the  superior  maxillary  bones,  the  orbitar  processes 
of  the  malar  bones,  and  the  vertical  processes  of  the  palate  bones, 
support  and  transmit  the  effort  which  takes  place  in  the  first  di- 
rection, while  the  zygomatic  processes  forcibly  press  the  bones  of 
the  face  against  each  other,  and  powerfully  resist  separation  out- 
wardly or  laterally.  The  lower  jaw  falls  by^  its  own  weight,  when 
its  elevators  are  relaxed;  the  external  pterygoid  muscles,  and 
those  attached  to  the  os  hyoides,  complete  this  motion,  the  centre 
of  which  is  not  in  the  articulation  of  the  jaw  to  the  temporal 
bones,  but  corresponds  to  a line  that  should  cross  the  coronoid 
processes,  a little  above  the  angles  of  the  jaw.  It  is  around  this 
axis,  that,  in  falling,  the  lower  jaw  performs  a motion  of  rota- 


OF  DIGESTION. 


97 

tion,  by  which  its  condyles  are  turned  forwards,  while  its  angles 
are  carried  backwards.  In  children,  the  coronoid  processes  stand- 
ing off  at  a smaller  distance  from  the  body  of  the  bone,  of  which 
they  have  nearly  the  same  direction,  the  centre  of  motion  is 
always  in  the  glenoid  cavities,  which  the  condyles  never  quit, 
however  much  the  jaw  may  be  depressed.  By  this  arrangement, 
nature  has  guarded  against  dislocation,  which  would  have  been 
frequent  at  an  early  period  of  life,  from  crying,  during  which, 
the  jaw  is  depressed  beyond  measure,  or  when  not  knowing 
the  just  proportion  between  the  capacity  of  the  mouth,  and  the 
size  of  the  bodies  they  would  put  into  it,  children  endeavour 
to  introduce  those  which  it  cannot  receive.  The  lower  jaw 
forms  a double  bended  lever  of  the  third  kind,  in  which  the 
power,  represented  by  the  temporal,  masseter  and  internal 
pterygoid  muscles,  lies  between  the  fulcrum  and  the  resistance, 
at  a smaller  or  greater  distance  from  the  chin. 

The  mode  of  articulation  of  the  jaw  to  the  temporal  bones, 
allows  it  only  a motion  upwards  and  downwards,  in  which  the 
teeth  of  both  jaws  meet  like  the  blades  of  scissors,  and  a lateral 
motion,  in  which  the  teeth  glide  on  each  other,  producing  a fric- 
tion well  calculated  to  grind  the  food,  which  in  the  first  part  of 
the  act  of  mastication  was  torn  or  divided. 

VIII.  In  carnivorous  animals,  the  levator  muscles  of  the 
under  jaw,  especially  the  temporals  and  masseters,  are  prodi- 
giously large  and  powerful.  In  them,  the  coronoid  processes, 
to  which  the  temporal  muscles  are  attached,  are  very  promi- 
nent; the  condyles  are  received  into  a very  deep  cavity;  while 
in  herbivorous  animals,  on  the  contrary,  they  are  less  strong 
and  bulky,  and  the  pterygoid  muscles,  by  whose  action  the  late- 
ral or  grinding  motion  is  performed,  are  stronger  and  more 
marked.  The  glenoid  cavities  are  also  in  them  wide  but  shal- 
low, so  that  they  allow  the  condyles  to  move  freely  on  their 
surface.  The  comparative  power  of  the  levator  and  abductor 
muscles  of  the  lower  jaw,  may  be  easily  appreciated,  by  view- 
ing the  temporal  and  zygomatic  fossae.  Their  depth  is  always 
in  an  inverse  ratio,  and  proportioned  to  the  bulk  of  the  muscles 
which  they  contain.  In  carnivorous  animals,  the  zygomatic 
arch,  to  which  , the  masseter  is  attached,  is  depressed,  and 
seems  to  have  yielded  to  the  effort  of  the  muscle.  In  the  point 

N 


98 


OF  DIGESTION. 


of  view  which  we  have  just  taken,  man  holds  a middle  station 
between  carnivorous  animals  and  those  which  feed  on  vegetable 
substances;  nothing,  however,  determines  his  nature  better  than 
the  composition  of  his  dental  arches. 

IX.  The  small  white  and  hard  bones  which  form  the  dental 
arches,  are  not  alike  in  all  the  animals  whose  jaws  are  furnished 
with  them.  All  have  not,  as  man,  three  kinds  of  teeth.  The 
laniary*  teeth  are  not  to  be  met  with,  in  the  numerous  class  of 
rodentia.  Some  are  without  incisors;  the  former  appear  more 
fitted  to  tear  fibrous  tissues  which  offer  much  resistance.  In 
carnivorous  animals,  they  are  likewise  very  long,  and  bent  like 
curved  pincers.  The  grinders  are  principally  employed  in  grind- 
ing substances  previously  divided  by  the  laniary  teeth,  which 
tear  them,  or  by  the  incisors,  which,  in  meeting  as  the  blades  of 
scissors,  fairly  cut  them  through:  the  latter,  of  which  each  jaw 
contains  four,  acting  only  on  bodies  which  present  but  a slight 
resistance,  are  placed  at  the  extremity  of  the  maxillary  lever. 
The  grinders  are  brought  nearer  to  the  fulcrum,  and  it  is  on 
them  that  the  great  stress  of  mastication  rests.  If  we  wish  to 

• After  the  example  of  several  naturalists,  I have  thought  it  right  to  give 
that  name  to  the  canine  teeth;  in  the  first  place,  because  their  principal  use 
being  to  lacerate  or  tear  fibrous  tissues,  it  is  fit  that  they  should  have  a name 
from  their  manner  of  acting  on  the  food,  as  is  the  case  with  tlie  incisors  and 
molares:  in  the  second  place,  because  the  word  canine  may  lead  to  an  errone- 
ous conception,  by  leading  to  a belief  that  this  kind  of  tooth  belongs  only  to 
one  kind  of  carnivorous  animals,  while  they  are  stronger  and  more  distinct  in 
the  lion,  the  tiger,  &c. 

Such  an  explanation  is  indispensable,  at  a period  when  every  body  aspires 
to  the  easy  glory  of  introducing  innovations  in  language.  The  invention  of 
words  is,  however,  in  the  opinion  of  a celebrated  female  writer,  a decided 
symptom  of  barrenness  of  ideas. 

The  teeth  differ  essentially  from  the  other  bones,  by  the  acute  sensibility 
with  which  they  are  endowed;  2dly,  by  the  nerves  which  may  be  traced  into 
them,  while  they  seem  to  be  wanting  in  every  other  part  of  the  osseous  sys- 
tem; 3dly,  by  the  mode  of  distribution  of  the  blood  vessels:  these  penetrate 
into  them  at  an  aperture  which  is  seen  at  the  extremity  of  their  root,  and  they 
expand  in  the  mucous  membrane  contained  in  the  tooth,  and  which  forms  the 
most  essential  part  of  the  bone;  4thly,  by  their  not  undergoing  any  change  from 
exposure  to  the  air,  a property  which  they  owe  to  the  enamel  which  covers 
them  externally.  It  has  been  said,  with  justice,  that  nature,  in  sheathing  the 
tooth  with  this  covering,  has  Imitated  the  process  of  tempering,  by  means  of 
which  we  harden  the  edge  of  steel  or  iron  tools. 


OF  DIGESTION. 


crush  a very  hard  substance,  we  instinctively  place  it  between 
the  last  large  grinders,  and  by  thus  shortening  considerably  the 
lever,  between  the  resistance  and  the  fulcrum,  we  improve  on 
the  lever  of  the  third  kind,  which,  though  most  employed  in 
the  animal  economy,  acts  the  most  unfavourable.  The  laniary 
teeth  have  very  long  fangs,  which  lying  deeply  buried  in  the 
alveolar  processes,  give  them  a degree  of  firmness  to  enable 
them  to  act  powerfully^  without  any  danger  of  being  loosened 
from  their  situation. 

The  enamel  which  covers  the  teeth,  preserves  the  substance 
of  the  bone  exposed  to  the  contact  of  the  air,  from  the  injuri- 
ous effects  which  would  not  fail  to  result  from  direct  exposure, 
and  as  enamel  is  much  harder  than  bone,  it  enables  the  teeth  to 
break  the  hardest  bodies  without  injury.  The  concentrated  acids 
soften  this  substance  and  occasion  a painful  affection  of  the 
teeth.  The  sensibility  possessed  by  these  bones  is  seated  in 
the  mucous  membrane  which  lines  their  inward  cavity,  through 
which  are  distributed  the  vessels  and  nerves,  which  enter  by 
openings  at  their  roots.  This  membrane  is  the  seat  of  a great 
number  of  diseases,  to  which  the  teeth  are  subject.  The  enamel, 
incessantly  worn  by  repeated  friction,  grows  and  repairs  its 
waste.  The  alveolar  processes  which  receive  the  fangs  of  the 
teeth,  firmly  embrace  them,  and  all  of  them  being  exactly  coni- 
cal in  form,  every  point  of  these  small  cavities,  and  not  merely 
theh  lower  part  at  which  the  nerves  and  vessels  enter,  supports 
the  pressure  which  is  applied  to  these  bones.  When  from  acci- 
dental causes,  or  in  the  progress  of  age,  the  teeth  are  gone,  their 
alveoli  contract,  then  disappear;  the  gums,  a reddish  and  dense 
membranous  substance,  which  connects  the  teeth  to  the  sockets, 
harden  and  becomes  callous  over  their  thinned  edges.  Old  men 
who  have  lost  all  their  teeth,  masticate  but  imperfectly,  and 
this  circumstance  is  one  of  the  causes  of  their  slow  digestion, 
as  the  gastric  juice  acts  with  difficulty  on  food,  whose  particles 
are  not  sufficiently  divided. 

X.  Salivary  solution.  The  above  mechanical  trituration  is  not 
the  only  change  which  the  food  undergoes  in  the  mouth.  Sub- 
jected to  the  action  of  the  organs  of  mastication,  which  over- 
come the  force  of  cohesion  of  its  molecules,  it  is  at  the  same 


OF  DIGESTION. 


100 

time  imbued  with  the  saliva.  This  fluid,  secreted  by  the  gland* 
placed  in  the  vicinity  of  the  mouth,  is  poured,  in  considerable 
quantity,  into  that  cavity  during  mastication. 

The  saliva  is  a transparent  and  viscous  fluid,  formed  of  about 
four  parts  of  water  and  one  of  albumen,  in  which  are  dissolved, 
phosphates  of  soda,  of  lime,  and  of  ammonia,  as  well  as  a small 
quantity  of  muriate  of  soda;  like  all  other  albuminous  fluids,  it 
froths  when  agitated,  by  absorbing  oxygen,  for  which  it  appears 
to  have  a strong  affinity.  Its  affinity  for  oxygen  is  such,  that 
one  may  oxydize  gold  and  silver,  by  triturating  in  saliva  thin 
leaves  of  those  metals  which  are  of  such  difficult  oxvdizement. 

The  irritation  occasioned  by  the  presence  or  the  desire  of 
food,  excites  the  salivary  glands,  they  swell  and  become  so 
many  centres  of  fluxion^  towards  which  the  humours  flow 
abundantly.  Bordeu  first  called  the  attention  of  physiologists 
to  the  great  quantity  of  nerves  and  vessels  received  by  the 
parotid,  maxillary  and  sublingual  glands,  from  the  carotid, 
maxillary  and  lingual  arteries,  from  the  portio  dura  of  the 
seventh  pair  of  nerves,  from  the  lingual  nerve  of  the  fifth  pair, 
which  penetrate  their  substance,  or  pass  over  a portion  of  their 
surface.  This  great  number  of  vessels  and  nerves'is  proportion- 
ed to  the  quantity  of  saliva  which  is  secreted,  and  this  is  esti- 
mated at  about  six  ounces  during  the  average  time  of  a meal. 
It  flows  in  greater  quantity,  when  the  food  that  is  used  is  acrid 
and  stimulating:  it  mixes  with  the  mucus  copiously  secreted 
by  the  mucous,  buccal,  labial,  palatine,  and  lingual  glands, 
and  with  the  serous  fluid  exhaled  by  the  exhalent  arteries  of 
the  mouth.  The  saliva  moistens,  imbues,  and  dissolves  the  ball 
formed  by  the  aliment,  brings  together  its  divided  molecules, 
and  produces  on  them  the  first  change.  There  can  be  no  doubt, 
that  the  saliva  mixing  with  the  food,  by  the  motion  of  the  jaws, 
absorbs  oxygen,  and  unites  to  the  alimentary  substances  a 
quantity  ol^  that  gas  fit  to  bring  about  the  changes  which  they 
are  ultimately  destined  to  undergo. 

XI.  The  muscular  parietes  of  the  mouth  are,  during  masti- 
cation, in  perpetual  action.  The  tongue  presses  on  the  food,  in 
every  direction,  and  brings  it  under  the  teeth;  the  muscles  of 
the  cheek,  especially  the  buccinator,  against  which  the  food  is 
pressed,  force  it  back  again  under  the  teeth,  that  it  may  be  duly 


OF  DIGESTION. 


101 

tritufated.  When  the  food  has  been  sufficiently  divided,  and 
imbued  with  saliva,  the  tip  of  the  tongue  is  carried  to  every 
part  of  the  mouth,  and  the  food  is  collected  on  its  upper  surface. 
The  food  having  been  thus  completely  gathered  together,  the 
tongue  presses  it  against  the  roof  of  the  mouth,  and  turning  its 
tip  upwards  and  backwards,  at  the  same  time  that  its  base  is 
depressed,  there  is  offered  to  the  food  an  inclined  plane,  over 
which  the  tongue  presses  it  from  before  backwards,  to  make, it 
clear  the  isthmus  of  the  fauces,  and  to  thrust  it  into  the  (eso- 
phagus. In  this  course  of  the  food  along  the  pharynx  and  into 
the  (Esophagus,  consists  deglutition,  a function  which  is  assisted 
by  the  co-operation  of  several  organs  whose  mechanism  is  rather 
complicated. 

XII.  Deglutition,  In  the  process  of  deglutition,  the  mouth 
closes  by  the  approximation  of  both  jaws;  at  the  same  time,  the 
submaxillary  muscles,  the  digastrici,,  the  genio-hyoidei^  the 
mylO’hyoidei,,  &c.  elevate  .the  larynx  and  pharynx,  by  drawing 
down  the  os  hyoides  towards  the  lower  jaw,  which  is  fixed  by 
its  levator  muscles.  The  hyo-glossus  muscle,  at  the  same  time 
that  it  elevates  the  os  hyoides,  depresses  and  carries  backwards 
the  base  of  the  tongue.  Then  the  epiglottis,  situated  between 
these  two  parts,  which  are  brought  together,  is  pushed  down- 
wards and  backwards  by  the  base  of  the  tongue,  which  lays 
it  over  the  opening  of  the  larynx.  The  alimentary  mass,  pressed 
between  the  palate  and  the  upper  surface  of  the  tongue,  slides 
on  the  inclined  plane  formed  by  the  latter,  and  pressed  by  its 
tip,  which  bends  back,  clears  the  isthmus  of  the  fauces.  The  mu- 
cous substance  which  exudes  from  the  surface  of  the  amygdalae 
further  facilitates  the  passage  of  the  food.  When  the  food  has 
thus  dropped  into  the  pharynx,  the  larynx  which  had  risen,  and 
had  come  forward,  and  which  in  that  motion  had  drawn  the 
pharynx  along  with  it,  descends  and  falls  backwards.  This  last 
organ,  stimulated  by  the  presence  of  the  food,  contracts,  and 
would  in  part  send  it  back  in  a retrograde  direction,  by  the 
nasal  fossse,  if  the  velum  palati,  elevated  by  the  action  of  the 
levatores  palati,  stretched  transversely  by  the  tensores  palati, 
was  not  applied  to  their  posterior  apertures,  and  towards  the 
openings  of  the  Eustachian  tubes.  Sometimes  this  obstacle  is 
overcome,  and  the  food  returns,  in  part,  by  the  nostrils.  This 


OP  DIGESTIOJf . 


i02 

happens,  when  during  the  act  of  deglutition,  we  attempt  either 
to  laugh  or  speak.  At  such  times,  the  air,  expelled  from  the 
lungs  with  a certain  degree  of  force,  elevates  the  epiglottis,  and 
meeting  the  alimentary  mass,  pushes  it  back  towards  the  nos- 
trils through  which  it  is  to  pass. — The  isthmus  faucium  is 
closed  against  the  return  of  the  food  into  the  mouth,  by  the 
swelling  of  the  base  of  the  tongue,  raised  by  the  action  of  the 
constrictor  isthmi  faucium,  and  of  the  constrictor  pharyngis 
superior,  which  are  small  muscles  contained  in  the  thickness  of 
the  pillars  of  the  velum. 

The  alimentary  mass  is  directed  towards  the  oesophagus,  and 
is  thrust  into  that  canal,  by  the  peristaltic  contractions  of  the 
pharynx,  which  may  be  considered  as  the  narrow  part  of  a 
funnel-like  tube.  The  solid  food  passes  behind  the  aperture  of  the 
larynx,  which  is  accurately  covered  over  by  the  epiglottis.  The 
liquids  flow  along  the  sides  of  that  opening,  along  two  channels 
easily  distinguished.  They  are  always  of  more  difficult  degluti- 
tion than  the  solids;  the  molecules  of  a fluid  have  an  incessant 
tendency  to  separate  from  one  another,  and  to  prevent  this 
separation,  the  organs  are  obliged  to  use  greater  exertion,  and 
to  embrace  with  more  precision  the  substance  that  is  swallow- 
ed. Thus,  it  is  observed,  in  those  cases  in  which  deglutition  is 
prevented  by  some  organic  affection  of  the  (Esophagus,  that  the 
patients,  though  they  have  the  power  of  swallowing  solid  food, 
find  it  difficult  to  swallow  a few  drops  of  a liquid,  and  are 
tortured  with  thirst,  though  they  have  still  the  power  of  satisfy- 
ing their  hunger. 

The  deglutition  of  air  and  of  gaseous  substances  is  still 
more  difficult  than  that  of  liquids,  because  these  elastic  fluids 
are  much  less  coercible,  and  it  requires  considerable  practice 
to  transmit  a mouthful  of  air  into  the  stomach.  M.  Gosse,  of 
Geneva,  had  acquired  that  power  from  repeated  experience, 
and  he  made  use  of  it  to  induce  vomiting  at  pleasure,  and  by 
the  application  of  that  faculty  to  the  interests  of  science,  he 
ascertained  the  digestibility  of  the  articles  of  food  in  most  com- 
mon use. 

The  food  descends  into  the  oesophagus,  propelled  by  the 
contractions  of  that  musculo-membranous  duct,  situated  along 
the  vertebral  column,  from  the  pharynx  to  the  stomach.  Mucus 


OF  DIGESTION. 


105 

is  secreted,  in  considerable  quantity,  by  the  naembrane  which 
lines  the  inner  part  of  the  oesophagus;  it  sheathes  the  substances 
which  pass  along  it,  and  renders  their  passage  moro  free.  The 
longitudinal  folds  of  the  inner  membrane,  allow  the  oesophagus 
to  dilate;  nevertheless,  when  it  is  stretched  beyond  measure, 
severe  pain  is  experienced,  occasioned,  no  doubt,  by  the  dis- 
tention of  the  nervous  plexuses,  formed  by  the  nerves  of  the 
eighth  pair  which  embrace  the  oesophagus,  as  they  course  along 
its  sides. — I purposely  avoid  speaking  of  the  weight  of  the 
food,  as  one  of  the  causes  which  enable  it  to  pass  along  the 
oesophagus.  Although,  in  man  as  in  quadrupeds,  that  weight  is 
no  obstacle  to  deglutition,  it  favours  that  function  in  so  slight  a 
degree,  that  the  diminution  of  muscular  contractility  at  the  ap- 
proach of  death,  is  sufficient,  altogether  to  prevent  it.  The  act 
of  drinking  is  then  attended  with  a noise  of  unfavourable  omen. 
This  noise  consists  in  a gurgling  of  the  fluid  which  has  a tend- 
ency to  get  into  the  larynx,  whose  opening  is  not  covered  over 
by  the  epiglottis;  and  if  it  be  insisted  upon,  that  the  patient  shall 
swallow  some  ptisan,  the  deglutition  of  which  is  impracticable, 
it  flows  into  the  trachea,  and  the  patient  dies  of  suflbeation. 

XIII.  Of  the  Abdomen.  Before  inquiring  any  further  into  the 
phenomena  of  digestion,  let  us  shortly  attend  to  the  cavity 
which  contains  its  principal  organs.  The  abdomen  is  almost 
entirely  filled  by  the  digestive  apparatus,  of  which  the  urinary 
passages  form  a part;  its  size,  the  structure  of  its  parietes,  are 
evidently  adapted  to  the  functions  of  that  apparatus.  The  ca- 
pacity of  the  abdomen  exceeds  that  of  the  other  two  great 
cavities;  its  dimensions  are  not  invariably  fixed,  as  those  of  the 
skull,  whose  size  is  determined  by  the  extent  of  its  osseous  and 
inelastic  parietes.  They  are  likewise  more  varying  than  those  of 
the  chest,  because,  the  degree  of  dilatation,  of  which  the  latter 
is  susceptible,  is  limited  by  the  extent  of  motion  of  which  the 
ribs  and  sternum  are  capable.  The  abdomen,  on  the  contrary, 
enlarges  in  a sort  of  indefinite  manner,  by  the  yielding  of  its 
soft  and  extensible  parietes.  In  some  cases  of  ascites,  the  abdo- 
men has  been  known  to  contain  as  much  as  eighty  pints  of 
liquid,  and  yet  death  has  not  followed  as  a consequence  of  so 
enormous  an  accumulation;  while  in  consequence  of  the  deli- 
cate texture  of  the  brain,  of  the  exact  fulness  of  tbe  skull,  and 


OF  DIGESTION, 


104 

especially  of  the  inflexibility  of  its  parietes,  the  slightest  effusions 
within  that  cavity  are  attended  with  so  much  danger;  while  the 
collection  of  a few  pints  of  fluid,  within  the  chest,  occasions 
suffocation.  This  vast  capacity  of  the  abdomen,  capable  of  being 
easily  increased,  was  required  in  a cavity  whose  viscera,  for  the 
most  part  hollow,  and  admitting  of  dilatation,  contain  substances 
varying  in  quality,  and  from  which  are  disengaged  gases  occu- 
pying a considerable  space.  What  a difference  is  there  not  in 
the  capacity  of  the  abdomen  of  animals,  according  to  the  quality 
of  the  food  on  which  they  feed!  Compare  the  slender  body  of 
the  tyger,  of  the  leopard  and  of  all  carnivorous  animals,  with  the 
heavy  mass  of  the  elephant,  of  the  ox,  and  of  all  animals  that 
wholly  or  principally  live  on  vegetable  food.  In  the  child,  who, 
for  his  growth  and  development,  digests  a considerable  quantity 
of  food,  the  abdomen  is  much  more  capacious  than  in  the  adult 
or  the  old  man.  In  the  child,  the  ensiform  cartilage  is  situated 
opposite  to  the  body  of  the  eighth  or  ninth  dorsal  vertebra.  In 
old  men,  it  descends  to  the  tenth  or  even  the  eleventh,  so  that  the 
capacity  of  the  abdomen  decreases  with  the  want  of  food,  and 
with  the  activity  of  digestion. 

The  internal  organs  of  the  body  are  incessantly  called  into 
action  by  different  causes,  and  excited  to  different  motions. 
The  action  of  the  arterial  system  tends  to  raise  the  cerebral 
mass,  and  to  impart  to  it  motions  of  elevation  and  depression. 
The  motion  of  the  ribs  brings  about  the  expansion  and  the 
compression  of  the  pulmonary  tissue;  the  heart,  which  adheres 
to  the  diaphragm,  drawn  down  by  that  muscle,  when  it  de- 
scends, strikes  against  the  parietes  of  the  chest,  every  time  its 
ventricles  contract.  The  abdominal  viscera  are  not  less  agitated 
by  the  motions  of  respiration;  they  experience  from  the  dia- 
phragm and  from  the  abdominal  muscles  a perpetual  action  and 
re-action,  by  means  of  which  the  circulation  of  the  fluids  in 
their  vessels  is  promoted,  the  course  of  the  food  in  the  alimen- 
tary canal  is  accelerated,  the  activity  of  digestion  increased,  and 
several  excretions,  as  of  the  urine  and  faeces,  performed. 

XIV.  Of  Digestion  in  the  Stomach.  The  food  which  is  taken 
into  the  stomach,  accumulates  gradually  within  its  cavity,  and 
separates  its  parietes,  which  are  always  in  contact  with  each 
other  whei^it  is  empty.  The  stomach,  in  that  mechanical  dis- 


OF  DIGESTION. 


105 


tention  by  the  food,  yields,  without  re-acting.  It  is  not,  however, 
absolutely  passive;  its  parietes  apply  themselves,  by  a general 
contraction,  by  a kind  of  tonic  motion,  to  the  food  which  lies 
within  it,  and  to  this  action  of  the  whole  stomach,  the  ancients 
gave  the  name  of  peristole.  As  the  stomach  dilates,  its  great 
curvature  is  thrust  forward,  the  two  folds  of  the  omentum  re- 
cede from  each  other,  receive  it  between  them,  and  embrace  its 
outer  and  dilated  part.  In  man,  the  principal  use  of  this  fold  of 
the  peritoneum,  appears  to  be  to  facilitate  the  dilatation  of  the 
stomach,  which  expands  chiefly  at  its  forepart,  as  may  be  ob- 
served by  inflating  it  in  a dead  body.  As  this  viscus  becomes 
distended  with  air,  the  two  folds  of  the  omentum  apply  them- 
selves to  its  surface,  and  if  this  membrane  is  pierced  with  a pin, 
at  the  distance  of  an  inch  from  its  great  curvature,  the  pin  is 
observed  to  get  nearer  to  this  curvature;  but  the  upper  portion 
of  the  omentum  can  alone  be  employed  in  this  use,  and  the 
whole  of  this  membranous  fold  is  never  entirely  occupied  by 
the  stomach.  Shall  we  say  with  Galen,  that  the  omentum  guards 
the  intestines  against  cold,  and  preserves  in  them  a gentle 
warmth,  necessary  to  digestion;  or  shall  we  admit  the  opinion 
of  those  who  maintain,  that  it  answers  the  purpose  of  a fluid, 
filling  up  spaces,  and  lessening  the  effect  of  friction  and  pressure 
from  the  anterior  parietes  of  the  abdomen;  or  shall  we  assert 
with  others,  that  the  use  of  the  omentum  is  to  allow  the  blood 
to  flow  into  it,  when  the  stomach,  in  a state  of  contraction,  is 
incapable  of  receiving  it.  May  not  the  blood  which  flows  so 
slowly  in  its  long  and  slender  vessels,  acquire  some  oleaginous 
quality  which  renders  it  fitter  to  supply  the  materials  of  bile?* 
The  stomach  likewise  stretches,  though  in  a less  distinct 
manner,  towards  its  lesser  curvature,  and  the  lamin£E  of  the 
gastro-hepatic  omentum  are  separated  from  each  other,  as  those 
of  the  omentum  majus.  Such  is  the  utility  of  the  gastro-hepatic 

* The  ometitum  is  one  of  those  parts,  the  use  of  which,  in  the  animal 
economy,  is  not  understood.  The  conjectures  enumerated  above  are  wholly 
gratuitous,  and  seem  to  me  abundantly  absurd.  Of  late  it  has  been  suggested, 
by  Dr.  James  Rush,  that  the  omentum  is  a reservoir,  or  depository  of  adipose 
matter,  from  which  the  system  may  derive  nourishment  in  its  extreme  exi- 
gences. This  hypothesis  is  at  least  as  plausible  as  any  which  has  been  advanced 
on  the  subject,  and  is  supported  with  con,siderable  ingenuity.  Vide  his  Inau- 
gural Thesis,  Philadelphia,  1809.'— Ed. 

o 


106 


OF  DIGESTION. 


omentum,  which  may  be  considered  as  a necessary  result  of  the 
manner  in  which  the  peritoneum  is  disposed  in  relation  to  the 
viscera  of  the  abdomen.  This  membrane,  which  extends  from 
the  stomach  to  the  liver,  so  as  to  cover  it,  could  not  fill  the 
space  which  separates  those  organs,  were  it  not  for  a kind  of 
membranous  communication  which  connects  them,  and  in  which 
are  contained  the  vessels  and  nerves,  which,  from  the  lesser 
curvature  or  the  posterior  edge  of  the  stomach,  course  towards 
the  concave  surface  of  the  liver.  This  gastro-hepatic  epiploon, 
may  besides,  by  the  separation  of  the  two  laminae  of  which  it  is 
formed,  favour  the  dilatation  of  the  hepatic  vein,  which  is 
situated,  as  well  as  the  vessels,  the  nerves  and  the  excretory 
ducts  of  the  liver,  in  the  thickness  of  its  right  border. 

The  stomach  has  ever  been  considered  as  the  principal  organ 
of  digestion,  yet  its  function  in  that  process  is  but  secondary 
and  preparatory:  it  is  not  in  the  stomach,  that  the  principal  and 
most  essential  phenomenon  of  digestion  takes  place,  I mean  the 
separation  of  the  nutritive  from  the  excrementitious  part  of  the 
food.  The  food,  when  received  into  the  stomach,  is  prepared 
for  this  separation  which  is  soon  to  be  performed,  it  becomes 
fluid,  and  undergoes  a material  alteration;  it  is  converted  into  a 
soft  and  homogeneous  paste,  known  under  the  name  of  chyme. 
What  is  the  agent  that  brings  about  this  change?  or  in  other 
Avords,  in  what  does  digestion  in  the  stomach  consist? 

As  it  is  frequently  necessary  to  clear  a spot  on  which  one 
means  to  build,  Ave  will  bring  forward  and  refute  the  hypotheses 
that  have  been  successively  broached,  to  explain  the  mechanism 
of  digestion.  They  may  be  enumerated,  as  follows: — concoction^ 
fermentation^  putrefaction^  trituration^  and  maceration  of  the 
food  taken  into  the  cavity  of  the  stomach. 

XV.  The  first  of  these  opinions  Avas  that  of  the  ancients  and 
of  the  father  of  physic;  but,  by  the  term  concoction^  Hippocrates 
did  not  mean,  a phenomenon  similar  to  that  Avhich  takes  place, 
Avhen  food  is  put  into  a vessel  and  exposed  to  the  influence  of 
heat.  The  temperature  of  the  stomach,  Avhich  does  not  exceed 
hat  of  the  rest  of  the  body  (32  degrees  of  Reaumur’s  scale) 
Avould  be  insufficient.  Cold-blooded  animals  digest  equally  Avich 
the  Avarm-blooded,  and,  as  Van  Helmont  observ’es,  febrile  heat 
impairs  instead  of  increasing  the  powers  of  digestion.  In  the 


OF  DIGBSTIOlSr. 


107 

language  of  the  ancients,  concoction  means  the  alteration,  the 
maturation,  the  animalization  of  alimentary  substances,  assimi- 
lated to  our  nature,  by  the  changes  which  they  undergo  in  the 
cavity  of  the  stomach.  It  is,  however,  a verified  fact,  that  the 
natural  heat  of  the  stomach  promotes  and  facilitates  those 
changes.  The  experiments  of  Spallanzani  on  artificial  digestion, 
show,  that  the  gastric  juice  is  not  of  more  efficacy  than  plain 
water,  in  softening  and  dissolving  alimentary  substances,  when 
the  heat  is  below  seven  degrees  (of  Reaumur’s  scale);  that  its 
activity,  on  the  contrary,  is  greatly  increased  when  the  heat  is 
ten,  twenty,  thirty,  or  forty  degrees  above  the  freezing  point. 
The  digestion  in  the  cold-blooded  animals  is,  besides,  slower 
than  in  the  hot-blooded. 

XVI.  The  abettors  of  the  theory  of  fermentation  admit,  that 
the  food  taken  into  the  stomach  undergoes  an  inward  and  spon- 
taneous motion,  in  virtue  of  which  it  forms  new  combinations; 
and  as  the  process  of  fermentation  is  promoted,  bv/tidding  to 
the  substance  that  is  undergoing  that  change,  a certain  quan- 
tity of  the  same  that  has  already  undergone  the  process,  some 
have  supposed,  that  there  continually  exists  in  the  stomach  a 
leaven,  formed,  according  to  Van  Helmont,  by  a subtle  acid,  and 
consisting,  in  the  opinion  of  others,  of  a small  quantity  of  the 
food  that  remains  from  the  former  digestion.  But  indepen- 
dently of  the  circumstance  that  the  stomach  empties  itself  com- 
pletely, and  presents  no  appearance  of  leaven,  when  examined 
a few  hours  after  digestion,  substances  undergoing  fermentation 
require  to  be  kept  perfectly  at  rest,  whereas  the  food  is  exposed 
to  the  oscillatory  circulations  and  to  the  peristaltic  contractions 
of  the  stomach,  and  this  viscus  is  shaken  by  the  pulsations  of  the 
neighbouring  arteries;  it  is  besides  kept  in  continual  motion  by 
the  act  of  respiration.  In  fermentation,  gases  are  either  absorbed 
or  extricated,  neither  of  which  circumstances  takes  place  when 
the  stomach  is  not  out  of  order. 

It  should,  hov/ever,  be  stated,  in  support  of  the  opinion  that 
accounts  for  digestion  on  the  principle  of  fermentation,  that  we 
can  derive  nourishment  only  from  substances  capable  of  under- 
going fermentation,  and  that  the  substances  which  have  under- 
gone the  panary  and  saccharine  fermentation,  are  more  easily 
digested,  and  in  less  time.  This  imperceptible  fermentation,  if 


108 


OF  DIGESTION. 


it  really  take  place,  must  bear  a greater  analogy  to  these  two  last 
processes,  than  to  those  which  are  called  vinous  and  acetous  fer- 
mentation, but  no  one  can  differ  from  it  more  than  the  putrid 
fermentation. 

XVII.  There  have  been  physiologists,  however,  from  the 
time  of  Plistonicus,  the  disciple  of  Praxagoras,  who  maintain, 
that  digestion  is,  in  fact,  the  consequence  of  putrefaction.  But 
not  only  is  ammonia  not  disengaged  during  that  process,  but 
our  digestive  organs  have  the  power,  as  will  be  seen  presently, 
of  retarding,  or  of  suspending,  the  putrefaction  of  the  substances 
which  are  submitted  to  their  action.  Serpents,  which  in  con- 
sequence of  the  greater  dilatability  of  their  oesophagus,  and 
from  the  power  of  holding  asunder  their  jaws,  both  of  which 
are  moveable  nearly  in  an  equal  degree,  frequently  swal- 
low larger  animals  than  themselves,  and  take  several  days  to 
digest  them;  that  part  of  the  animal  exposed  to  the  action 
of  the  stomach,  is  observed  to  be  perfectly  fresh,  and  dis- 
solved to  a certain  extent,  while  the  part  which  remains  out, 
exhibits  signs  of  incipient  putrefaction.  In  fine,  notwithstand- 
ing the  heat  and  moisture  of  the  stomach,  the  food  does  not  re- 
main in  it  long  enough  to  allow  putrefaction  to  come  on,  even 
though  every  thing  else  should  favour  that  process.  Animals 
which  have  by  chance  swallowed  putrescent  animal  substances, 
either  reject  them  by  vomiting,  or,  as  Spallanzani  has  observed 
in  some  birds,  deprive  them  of  their  putridity. 

XVIII.  The  system  of  fermentation  was  invented  by  the 
chemists;  that  of  trituration,  by  the  mechanical  philosophers, 
who  compare  the  changes  which  substances  undergo  in  a mor- 
tar from  the  action  of  the  pestle,  to  the  changes  which  the  food 
undergoes  in  the  stomach.  But  how  different  is  the  triturating 
action  of  a pestle,  which  crushes  a substance  softer  than  itself 
against  a resisting  surface,  to  the  gentle  and  peristaltic  action  of 
the  fibres  of  the  stomach,  on  the  substances  which  it  contains. 
Trituration,  which  is  a mechanical  effect,  does  not  alter  the 
nature  of  the  substance  exposed  to  its  action;  but  the  food  is 
decomposed  and  no  longer  the  same  substance,  after  it  has  re- 
mained some  time  in  the  stomach.  As  this  evidently  absurd 
hypothesis  has  long  been  held  in  high  estimation,  it  will  not  be 


OF  DIGESTION, 


109 

improper  to  spend  a little  time  in  the  refutation  of  the  proofs 
which  are  adduced  in  its  support. 

The  manner  in  which  digestion  is  brought  about  in  birds, 
whose  stomach  is  muscular,  and  especially  in  the  gallinaceous 
fowls,  is  the  most  specious  argument  adduced  by  the  abettors  of 
mechanical  digestion.  Those  granivorous  birds  all  have  a dou- 
ble stomach;  the  first  is  called  the  crop,  its  sides  are  thin  and 
almost  entirely  membranous;  a fluid  is  abundantly  effused  on  its 
inner  surface,  the  seeds  on  which  they  feed  get  softened^  and 
undergo  a kind  of  preliminary  maceration  in  the  crop,  after 
which  they  are  more  easily  ground  by  the  gizzard,  which  is  a 
truly  muscular  stomach,  that  fulfils  the  office  of  organs  of  mas- 
tication, almost  entirely  deficient  in  that  class  of  animals.  The 
gizzard  acts  so  powerfully,  that  it  crushes  the  solid  substances 
exposed  to  its  action,  reduces  into  dust  balls  of  glass  and  crys- 
tal, flattens  tubes  of  tin,  breaks  pieces  of  metal,  and  what  is 
much  more  extraordinary,  breaks  with  impunity  the  points  of 
the  sharpest  needles  and  lancets.  Its  internal  part  is  lined  with 
a thick  semi-cartilaginous  membrane,  incrusted  with  a number 
of  small  stones  and  gravel,  taken  in  vrith  the  food  of  those  birds. 
The  turkey  cock  is,  of  all  other  fowls,  that  in  which  this  struc- 
ture is  most  apparent;  besides  the  small  pebbles  which  line  its 
inner  membrane,  its  cavity  contains,  almost  in  all  cases,  a num- 
ber of  them.  The  rubbing  together  of  these  hard  substances, 
exposed  along  with  the  seeds  among  which  they  are  mixed,  to 
the  action  of  the  sfomach,  may  assist  in  breaking  them  down. 
The  pieces  of  iron  and  the  pebbles  which  the  ostrich  swallows, 
some  of  which  Valisnieri  met  with  in  the  stomach  of  that  bird, 
are  destined  to  the  same  use.  But  this  mechanical  division  which 
the  gizzard  performs  in  the  absence  of  organs  of  mastication, 
does  not  constitute  digestion;  the  food,  softened  and  divided  by 
the  action  of  the  crop  and  of  the  gizzard,  passes  into  the  duode- 
num, and  exposed  in  that  intestine  to  the  action  of  the  biliary 
juices,  undergoes  within  it  the  changes  most  essential  to  the  act 
of  digestiop. 

The  singular  structure  of  the  lobster’s  stomach  is  not  more 
favourable  to  the  hypothesis  of  trituration.  In  that  crustaceous 
animal,  the  stomach  is  furnished  with  a real  mandibular  appa- 
ratus, destined  to  break  down  the  food.  There  are  found  in  it, 


110 


OP  DIGESTION. 


besides,  at  certain  times  of  the  year,  two  roundish  concretions, 
on  each  side,  under  its  internal  membrane.  These  concretions, 
improperly  termed  crabs’  eyes,  consist  of  carbonate  of  lime 
joined  to  a small  quantity  of  gelatinous  animal  matter;  they  dis- 
appear, when,  after  the  annual  shedding  of  the  shell,  the  exter- 
nal covering,  at  first  membranous,  becomes  solid  from  the  depo- 
sition of  the  calcareous  matter  of  which  they  are  formed. 

The  very  great  difference  between  the  stomach  of  these  ani- 
mals and  that  of  man,  ought  to  have  precluded  ev-ery  idea  of 
comparing  them  together.  Spallanzani  has  justly  observed,  that 
in  regard  to  the  muscular  power  of  the  parietes  of  the  stomach, 
animals  might  be  divided  into  three  classes,  the  most  numerous 
of  which  consists  of  those  creatures,  whose  stomach  is  almost 
entirely  membranous,  and  furnished  with  a muscular  coat  of 
very  little  thickness.  In  this  class  are  contained,  man,  quadru- 
peds, birds  of  prey,  reptiles,  and  fishes.  Notwithstanding  the 
weakness  of  that  muscular  coat,  Pitcairn,  by  a misapplied  cal- 
culation, has  estimated  its  power  at  12,951  pounds;  he  reckons 
at  248,335  pounds,  that  of  the  diaphragm  and  of  the  abdominal 
muscles  which  act  on  the  stontiach  and  compress  it  in  the  alter- 
nate motions  of  respiration.  What  does  so  exaggerated  a calcu- 
lation prove,  except,  as  Garat  observes,  that  this  vain  show  of 
axioms,  definitions,  scholia,  and  corollaries  with  which  works 
not  belonging  to  mathematics  have  been  disfigured,  have  strved 
only  to  protect  vague,  confused,  and  false  notions,  under  the 
cover  of  imposing  and  respected  forms.  One  need  only  intro- 
duce one’s  hand  into  the  abdomen  of  a living  animal,  or  a finger 
into  a wound  of  the  stomach,  to  ascertain  that  the  force  of  that 
viscus  on  its  contents,  does  not  exceed  a few  ounces. 

XIX.  The  learned  and  indefatigable  Haller  thought,  that  the 
food  was  merely  softened  and  diluted  by  the  gastric  juice.  This 
maceration  was,  in  his  opinion,  promoted  and  accelerated  by  the 
warmth  of  the  part,  by  the  incipient  putrefaction,  by  the  gentle 
but  continual  motions  which  the  alimentary  substance  under- 
goes. Maceration,  in  time,  overcomes  the  force  of  cohesion  of 
the  most  solid  substances;  but  by  dilution  it  never  changes  their 
nature.  Haller  rested  on  the  experiments  of  Albinus,  on  the 
conversion  of  membranous  tissues  into  mucilage,  by  protracted 
maceration. 


OF  DIGESTION. 


Ill 


la  ruminating  animals,  the  cavity  of  the  stomach  is  divided 
into  four  parts,  which  open  into  one  another,  and  of  which  the 
three  first  communicate  with  the  oesophagus.  When  the  grass, 
after  imperfect  trituration  by  the  organs  of  mastication,  whose 
power  is  inconsiderable,  has  reached  the  paunch,  which  is  the 
first  and  largest  of  the  four  stomachs,  it  undergoes  a real  mace- 
ration, together  with  an  incipient  acid  fermentationi>  The  con- 
tractions of  the  stomach  propel  the  food,  in  small  quantities  at 
a time,  into  the  bonnet,  which  is  smaller  and  more  muscular 
than  the  paunch;  it  coils  on  itself,  covers  with  mucus  the  already 
softened  food,  then  forms  it  into  a ball,  which  rises  into  the 
mouth,  by  a truly  antiperistaltic  motion  of  the  esophagus.  The 
alimentary  bolus,  after  having  been  chewed  over  again  by  the 
animal,  which  seems  to  enjoy  that  process,  descends  along  the 
oesophagus  into  the  third  stomach,  called  the  manyplus,  on  ac-. 
count  of  the  large  and  numerous  folds  of  its  inner  membrane. 
From  this  cavity  the  food  enters  into  the  abomasum,  in  which 
the  stomachic  digestion  is  completed.  Such  is  the  mechanism 
of  rumination,  a function  peculiar  to  animals  that  have  four  sto- 
machs; they  do  not,  however,  ruminate  at  all  periods  of  their 
life.  The  sucking  lamb  does  not  ruminate:  the  half  digested 
milk  does  not  pass  along  the  paunch  or  the  bonnet,  which  are 
useless,  but  at  once  descends  into  the  third  stomach.  Some  men 
have  been  capable  of  a kind  of  rumination;  the  alimentary  ball, 
after  descending  into  the  stomach,  shortly  after  rose  into  the 
mouth,  to  be  there  chewed  a second  time,  and  to  be  anew  im- 
bued with  saliva.  Conrad  Peyer  has  made  this  morbid  pheno- 
menon the  subject  of  a dissertation  entitled,  Mericoiogia^  sive 
de  Ruminantibus, 

This  fourfold  division  of  the  stomach,  so  favourable  to  Hal- 
ler’s theory,  is  observed  only  in  ruminating  animals.  But  though 
animals  are  in  general  monogastric,  as  man,  that  is,  provided 
with  only  one  stomach,  this  viscus  offers  a number  of  varieties, 
the  naost  remarkable  of  which  refer  to  the  relative  facility  which 
the  food  meets,  in  remaining  within  its  cavity.  The  insertion 
of  the  oesophagus  is  nearer  to  its  left  extremity,  and  the  great 
fundus  of  that  viscus  is  smaller,  as  animals  feed  more  exclusively 
on  flesh,  which  is  a substanceof  remarkably  easy  decomposition, 
and  not  requiring  for  its  digestion  a long  stay  in  the  stomach. 


OF  DIGESTION. 


112 

In  herbivorous  quadrupeds,  which  do  not  ruminate,  this  great 
fundus  forms  nearly  one  half,  sometimes  even  the  greater  part 
of  the  stomach,  as  the  oesophagus  enters  into  it  very  near  the 
pylorus.  In  some,  as  in  the  hog,  the  stomach  is  divided  into 
two  parts  by  a circular  contraction.  The  food  which  is  received 
into  the  great  fundus  of  the  stomach,  may  remain  longer  in  that 
viscus,  as  this  part  of  its  cavity  lies  out  of  the  course  of  the  ali- 
ment. 

XX.  Of  the  gastric  juice.  Of  all  the  organs,  the  stomach 
probably  receives,  in  proportion  to  its  bulk,  the  greatest  number 
of  blood-vessels;  in  its  membrano  muscular  parietes,  which  are 
little  more  than  the  twelfth  part  of  an  inch  in  thickness,  there  is 
distributed  the  coronary  artery  of  the  stomach,  entirely  destined 
to  that  organ;  the  pyloric,  the  right  gastro-epiploic,  given  oflF  by 
the  hepatic  artery.  The  greater  part  of  the  blood,  therefore, 
which  passes  from  the  aorta  to  the  coeliac  artery  goes  to  the 
stomach,  for,  though,  of  the  arteries  into  which  that  trunk  is 
divided,  the  coronary  of  the  stomach  is  the  least,  the  arteries 
of  the  liver  and  spleen  send  to  the  stomach  several  pretty  con- 
siderable branches,  before  entering  the  viscera  to  which  they 
are  more  particularly  allotted.  One  need  only  observe  the  great 
disproportion  between  the  stomach  and  the  quantity  of  blood 
which  it  receives,  to  conclude,  that  this  fluid  is  not  merely  sub- 
servient to  its  nutrition,  but  is  destined  to  furnish  the  materials 
of  some  secretion. 

The  secretion  in  question,  is  that  of  the  gastric  juice,  which 
is  most  abundantly  supplied  by  arterial  exhalation,  from  the  in- 
ternal surface  of  the  stomach;  it  is  most  active  at  the  instant 
when  the  food  received  within  its  cavity,  excites  irritation, 
transforms  it  into  a centre  of  fluxion  towards  which  the  fluids 
flow  from  all  directions.  The  state  of  fulness  of  the  stomach, 
favours  the  afflux  of  the  fluids  in  the  vessels,  as,  in  conse- 
quence of  the  extension  of  its  parietes  previously  collapsed,  the 
vessels  are  no  longer  bent  and  creased.  The  arteries  of  the 
stomach,  of  the  spleen  and  liver,  arising  from  a common  trunk, 
it  may  be  easily  understood  how,  when  the  stomach  is  empty, 
little  blood  enters  into  it,  in  that  state  of  contraction;  how,  at 
the  same  time,  the  spleen  which  is  less  compressed,  and  the 
liver,  must  receive  a larger  supply  of  blood,  and  again  a smaller 
quantity,  when  the  stomach  is  full. 


OP  DIGESTION. 


113 

The  gastric  juice,  the  result  of  arterial  exhalation,  mixes  with 
the  mucus  poured  out  by  the  mucous  follicles  of  the  internal 
membrane  of  the  stomach.  This  mixture  renders  it  viscous 
and  ropy  like  the  saliva,  to  which  in  man,  the  gastric  juice  bears 
a great  analogy.  It  is  very  difhcult  to  obtain  it  pure,  so  as  to 
analyze  it,  and  even  if  by  long  fasting,  the  stomach  should 
be  deprived  of  the  alimentary  residue,  which  might  affect  its 
purity,  one  could  not  prevent  its  being  mixed  with  a certain 
quantity  of  liquid  bile,  which  always  flows  back  through  the 
pyloric  orifice,  turns  yellow  the  inner  surface  of  the  stomach, 
in  the  neighbourhood  of  that  orifice,  and  even  imparts  a certain 
degree  of  bitterness  to  the  gastric  juice.  The  passage  of  the  bile 
from  the  duodenum  into  the  stomach,  cannot  be  looked  upon 
as  morbid;  it  occurs  in  the  most  perfect  health,  which  has  led 
to  a well  founded  opinion,  that  a small  quantity  of  the  biliary 
fluid  is  a useful  stimulus  to  the  stomach.  This  opinion  is  con- 
firmed by  an  observation  of  Vesalius,  who  relates,  that  he  found 
the  ductus  communis  choledochus  opening  into  the  stomach,  in 
the  body  of  a convict  noted  for  his  voracious  appetite.  It  is 
further  confirmed  by  what  is  observed  in  birds  of  prey,  in  the 
pike,  &c.  who  digest  easily  and  with  great  rapidity,  because  the 
termination  into  the  duodenum  of  the  ductus  communis  chole- 
dochus, being  very  near  to  the  pylorus,  the  bile  easily  ascends 
into  the  stomach,  and  is  always  found  there  in  considerable 
quantity. 

To  obtain  some  of  this  gastric  juice,  it  is  necessary  either  to 
open  a living  animal  under  the  influence  of  hunger,  or  to  oblige 
anight  bird  of  prey,  as  an  owl,  to  swallow  small  spunges  fastened 
to  a long  thread.  When  the  spunge  has  remained  for  a short 
time  in  the  stomach,  it  is  withdrawn  soaked  with  gastric  juice, 
of  which  the  secretion  has  been  promoted  by  its  presence  in  the 
stomach. 

The  gastric  juice,  in  its  natural  state,  is  neither  acid  nor  alka- 
line; it  does  not  turn  red  or  green,  vegetable  blue  colours.*  Its 

* There  is  some  difference  of  opinion  on  this  point.  Carminati  declares  that 
in  carnivorous  animals  the  gastric  fluid  is  add,  that  in  phytiferous  it  is  alkaline^ 
and  that  in  those  which  live  indiscriminately  on  animal  and  vegetable  food,  it 
is  neither  add  nor  alkaline.  By  Brugnatelli  it  is  said  that,  in  all  animals,  it  is 
«niformly  add.  That  the  gastric  liquor  is  occasionally  add  in  the  human  specie^ 

P 


OF  DIGESTION. 


114 

mogt  remarkable  quality  is,  its  singularly  powerful  solvent  fa- 
culty, the  hardest  bones  cannot  withstand  its  action;  it  acts  on 
those  on  which  the  dog  feeds,  it  combines  with  all  their  organ- 
ized and  gelatinous  parts,  reduces  them  to  a calcareous  residue, 
forming  those  excrementitious  substances  so  absurdly  called 
album  grmcum^  by  the  older  chemists.  The  solvent  energy  of 
the  gastric  juice  is  in  inverse  ratio  of  the  muscular  strength  of 
the  parietes  of  the  stomach,  and  in  those  animals  in  which  the 
parietes  of  that  viscus  are  very  thin,  and  almost  entirely  mem- 
branous, it  has  most  power  and  activity.  In  the  numerous  class 
of  zoophytes,  it  alone  suffices  to  effect  decomposition  of  the 
food,  always  more  prompt  when  accompanied  by  warmth  of 
the  atmosphere,  as  was  observed  by  du  Trembley,  in  the  polypi, 
which  in  summer  dissolve  in  twelve  hours,  what  in  colder 
weather  it  would  take  three  days  to  digest.  In  the  actinia,  in 
the  holothuria,  the  gastric  juice  destroys  even  the  shells  in  the 
muscles  which  they  swallow.  Are  we  not  all  acquainted  with 
the  peculiar  flavour  of  oysters,  how  much  they  tend  to  whet  the 
appetite?  this  sensation  depends  less  on  the  salt  water  contained 
in  the  shell,  than  on  the  gastric  juice  which  acts  on  the  tongue, 
which  softens  its  tissue  and  quickens  its  sensibility.  This  mu- 
cous substance,  when  received  into  the  stomach,  promotes  the 
digestion  of  the  food  which  is  afterwards  taken  into  it;  for,  the 
oyster  itself  is  very  little  nutritious,  and  isused  rather  as  a con- 
diment, than  as  affording  nourishment. 

The  gastric  juice  not  only  pervades  and  dissolves  the  food 
received  into  the  stomach,  but  it  unites  and  intimately  combines 
with  it,  completely  alters  its  nature  and  changes  its  composition. 
The  gastric  juice  acts,  in  a manner  peculiar  to  itself,  on  the  food 


cannot  be  denied.  It  has  indeed  been  found  so  both  by  Reaumur  and  Hunter, 
and  in  subjects  where  there  was  no  reason  to  presume  it  had  become  vitiated 
by  a disordered  condition  of  the  stomach. 

We  are  inclined  to  believe  that  the  gastric  fluid  has  pretty  nearly  the  same 
properties  in  all  animals.  In  support  of  this  conclusion  we  may  appeal  to  the 
fact  which  has  been  verified  by  repeated  experiments,  that  both  carnivorous 
and  phytiferous  animals  digest  and  thrive  well  on  an  exchange  of  food,  tlie  one 
being  made  to  feed  exclusively  on  vegetable  and  the  other  on  animal  matter. 
Vide  Experiments  of  J.  Hunter  and  Spallanzani. — Ed. 


©F  DIGESTION. 


exposed  to  its  action,  and  far  from  inducing  a beginning  of  pu- 
trefaction, suspends  on  the  contrary  and  corrects  putrescency. 
This  antiseptic  quality  of  the  gastric  juice,  suggested  the  prac- 
tice of  moistening  ulcers  with  it  to  accelerate  their  cure,  and  the 
experiments  made  at  Geneva  and  in  Italy,  have,  it  is  said,  been 
fully  successful.  I have  made  similar  experiments  with  saliva, 
which,  there  is  every  reason  to  consider,  is  similar  to  the  gas- 
tric juice;  and  I have  seen  old  and  foul  ulcers  assume  a better 
appearance,  the  granulations  become  healthy,  and  the  affection 
rapidly  advance  towards  a cure,  from  the  use  of  that  irritating 
fluid.  I had  under  my  care  an  obstinate  sore  on  the  inner  ankle  of 
the  left  leg  of  an  adult;  notwithstanding  the  external  application 
of  powdered  bark,  and  of  compresses  soaked  in  the  most  deter- 
gent fluids,  this  sore  was  improvingvery  slowly,  when  I bethought 
myself  of  moistening  it  every  morning  with  my  saliva,  the  secre- 
tion of  which  was  increased  by  the  hideous  aspect  of  the  sore. 
From  that  time,  the  patient  evidently  mended,  and  his  wound 
contracting  daily,  atjast  became  completely  cicatrized. 

However  powerful  the  efficacy  of  the  gastric  juice,  to  dissolve 
the  alimentary  substances,  it  does  not  direct  against  the  coats  of 
the  stomach  its  active  solvent  faculty.  These  parietes  endowed 
with  life,  powerfully  resist  solution.  The  lumbrici  so  tender  and 
delicate,  for  the  same  reason,  can  exist  within  it,  without  being 
in  the  least  affected  by  it;  and  such  is  this  power  of  vital  resist- 
ance, that  the  polypus  rejects  unhurt  its  arms,  when  it  happens 
to  swallow  them  among  its  food.'*’  But  when  the  stomach  and 
the  other  organs  have  lost  their  vitality,  its  parietes  yield  to  the 
solvent  power  of  the  juices  which  it  may  contain,  they  become 
softened,  and  even  in  part  destroyed,  if  we  may  believe  Hunter, 
who  found  its  inner  membrane  destroyed  in  several  points  in  the 
body  of  a criminal,  who  for  some  time  before  his  execution,  had 
been  prevailed  upon,  in  consideration  of  a sum  of  money,  to  ab- 
stain from  food.f 

• It  had  been  thought,  that  no  animal  could  live  on  the  flesh  of  its  own  kind, 
and  this  circumstance  was  explained  on  the  same  principle;  but  to  refute  it, 
■we  need  only  quote  the  instance  of  cannibals,  and  of  several  tribes  of  carni- 
vorous animals,  who,  in  the  absence  of  other  prey,  devour  one  another. 

f The  fact  of  the  stomach  itself,  in  some  instances,  being  partly  dissolved 


OF  DIGESTION. 


116 

The  gastric  juice  is  capable,  even  after  death,  of  dissolving 
food  introduced  into  the  stomach,  by  a wound  made  into  it,  pro- 
vided the  animal  still  preserves  some  degree  of  animal  heat.  It 
acts  on  vegetable  and  animal  substances  triturated  and  put 
into  a small  vessel,  such  as  those  under  which  Spallanzani,  in 
his  experiments  on  artificial  digestion,  kept  up  a moderate  heat. 
Let  us  not  however  consider  as  the  same,  this  solution  of  the 
food  in  the  gastric  juice,  out  of  the  stomach,  and  that  which  oc- 
curs in  digestion  within  the  organ. Everything  tends  to  show, 
that  the  stomach  ought  not  to  be  considered  as  a chemical  ves- 
sel, in  which  there  takes  place  a mixture  giving  rise  to  new  com- 
binations. The  tying  the  nerves  of  the  eighth  pair,  the  use  of 
narcotics  and  of  opium,  intense  thought,  every  powerful  affection 
of  the  mind,  trouble  or  even  entirely  suspend  digestion  in  the 
stomach,  which  cannot  take  place  independently  of  nervous  in- 
fluence. Yet  this  nervous  influence  may  possibly  not  concur  di- 
rectly, and  of  itself,  to  stomachic  digestion;  it  is  perhaps  merely 
relative  to  the  secretion  of  the  gastric  juice,  which  the  ligature 
of  the  nerves,  the  action  of  narcotics  or  of  other  substances  may 
impede,  alter,  or  even  completely  suspend. 

It  is  now  pretty  generally  admitted,  that  digestion  in  the 
stomach,  consists  in  the  solution  of  the  food  in  the  gastric  juice. 
This  powerful  solvent  penetrates,  in  every  direction,  the  ali- 
mentary mass,  removes  from  one  another,  or  divides  its  mole- 
cules, combines  with  it,  alters  its  inward  composition,  and  imparts 
to  it  qualities  very  different  from  those  which  it  possessed  before 
the  mixture.  If,  in  fact,  a mouthful  of  wine  or  of  food  is  re- 
jected, a few  minutes  after  being  swallowed,  the  smell,  the 
flavour,  all  the  sensible  and  chemical  qualities  of  such  substances, 

by  the  operation  of  the  gastric  liquor  after  death,  which  -was  first  noticed  by 
Mr.  Hunter,  has  since  been  fully  confirmed  by  the  observations  of  Mr.  Allan 
Burns,  and  others. — Ed. 

* In  the  experiments  alluded  to  above,  meat  and  bread  mixed  with  the  gas- 
tric fluid  were  reduced  to  a gelatinous  resembling  in  all  its  sensible  pro- 
perties, the  natural  chyme.  By  the  artificial  process  however,  a much  longer 
time  was  found  necessary  to  effect  this  end.  It  is  to  be  regretted  that  these 
experiments  have  not  been  made  with  greater  accuracy.  To  determine  with 
precision  the  identity  of  ttie  artificial  and  natural  process,  the  same  sort  of  food 
should  be  used,  and  the  two  masses  aftertvards  chemically  analysed. — Eu. 


OF  DIGESTION. 


117 

are  so  completely  altered,  that  they  can  scarcely  be  recognized; 
the  vinous  substances  turned,  to  a certain  degree,  sour,  are  no 
longer  capable  of  the  acetous  fermentation.  The  energy  of  the 
solvent  power  of  the  gastric  juice,  perhaps  over-rated  by  some 
physiologists,  is  sufficient  to  dissolve  and  reduce  into  a pulp,  the 
hardest  bones  on  which  some  animals  feed.  It  is  highly  probable, 
that  its  chemical  composition  varies  at  different  times;  that  it  is 
acid,  alkaline  or  saponaceous,  according  to  the  nature  of  the 
food.  Although  the  gastric  juice  be  the  most  powerful  agent  of 
digestion,  its  solvent  power  requires  to  be  aided  by  several  se- 
condary causes,  as  warmth,  which  seems  to  increase,  and,  in  a 
manner,  to  concentrate  itself  in  the  epigastric  region,  as  long  as 
the  stomach  is  engaged  in  digestion;  a sort  of  inward  fermenta- 
tion which  cannot  be,  strictly  speaking,  compared  to  the  decom- 
position which  substances  subject  to  putrefaction  and  acescency 
undergo.  The  gentle  and  peristaltic  action  of  the  muscular  fibres 
of  the  stomach,  which  press,  in  every  direction,  on  the  alimen- 
tary substance,  performs  on  it  a slight  trituration,  while  the 
moisture  of  the  stomach  softens  and  macerates  the  food,  before 
it  is  dissolved;  one  might  therefore  say,  that  the  process  of  di- 
gestion is  at  once  chemical,  mechanical,  and  vital;  in  that  case, 
the  authors  of  the  theories  that  have  been  broached,  have  been 
wrong,  only  in  ascribing  to  one  cause,  such  as  heat,  fermentation, 
putrefaction,  trituration,  maceration,  and  the  action  of  the  gas- 
tric juice,  a process  which  is  the  result  of  a concurrence  of 
these  causes  united. 

The  food  remains  in  the  stomach,  during  a longer  or  shorter 
space  of  time,  according  as  by  its  nature,  it  yields  more  or  less 
readily  to  the  changes  which  it  has  to  undergo.  Gosse  of  Ge- 
neva, ascertained,  by  experiments  performed  on  himself,  that 
the  animal  and  vegetable  fibre,  concrete  albumen,  white  and  ten- 
dinous parts,  paste  containing  fat  or  butter,  substances  which 
have  either  not  undergone  fermentation,  or  vyhich  do  not  readily 
undergo  that  process,  remain  longer  in  the'stomach,  and  offer 
more  resistance  to  the  gastric  juice,  than  the  gelatinous  parts  of 
animals  or  vegetables,  fermented  bread,  &c.;  that  the  latter  re- 
quired but  an  hour  for  their  complete  solution,  while  the  former 
were  scarcely  dissolved  at  the  end  of  several  hours. 

XXI.  The  following  case  throws,  I think,  some  light  on 


OP  DIGESTION. 


il8 

the  mechanism  and  importance  of  the  action  of  the  stomach  in 
digestion.  The  patient  was  a woman  whom  I had  frequent  op- 
portunities of  examining  at  the  “ Hopital  de  la  Charite”  at 
Paris,  in  the  clinical  wards  of  Professor  Corvisart,  in  which 
she  died  on  the  ninth  Nivose  of  the  year  X.  after  six  months’ 
stay  in  the  hospital. 

A fistulous  opening  of  an  oval  form,  an  inch  and  an  half  in 
length,  and  upwards  of  an  inch  in  breadth,  situated  at  the  lower 
part  of  the  chest,  at  the  upper  and  left  side  of  the  epigastric  re- 
gion, afforded  an  opportunity  of  viewing  the  inner  part  of  the 
stomach,  which  when  empty  of  food,  appeared  of  a vermilion 
colour,  was  covered  with  mucus,  its  surface  wrinkled  over  with 
folds  about  half  an  inch  deep,  and  enabled  one  to  distinguish  the 
vermicular  undulations  of  these  folds,  and  of  all  the  parts  which 
were  in  sight.  The  patient,  who  was  then  forty-seven  years  of 
age,  had  had  this  fistula  since  she  was  in  her  thirty-eighth  year. 
Eighteen  years  before,  she  had  fallen  on  the  threshhold  of  a 
door,  and  the  blow  had  struck  against  her  epigastric  region.  The 
place  remained  affected  with  pain,  and  she  became  incapable  of 
walking  or  of  sitting,  otherwise  than  bent  forward  and  to  the 
left  side.  At  the  end  of  this  long  interval,  a phlegmonous  and 
oblong  tumour  appeared  on  the  injured  spot:  during  the  nausea 
and  vomiting  which  came  on  afterwards,  the  tumour  broke,  and 
there  escaped  at  the  wound,  which  was  left  by  this  rupture,  two 
pints  of  a fluid  which  the  patient  had  just  swallowed  to  obtain 
relief.  From  that  time,  the  fistula,  which  at  first  would  scarcely 
have  admitted  the  tip  of  the  little  finger,  increased  daily;  at  first 
it  allowed  only  the  fluids  to  pass,  but,  on  the  eighth  day,  the  solid 
food  came  away  freely,  and  continued  to  do  so  till  she  died. 
When  admitted  into  the  hospital,  she  ate  as  much  as  three 
women  of  her  age,  she  voided  about  a pint  of  urine  and  went  to 
stool  only  once  in  three  days.  Her  faeces  were  yellowish,  dry, 
rounded,  and  weighed  more  than  a pound.  Her  pulse  was  very 
feeble  and  extremely  slow,  its  pulsation  scarcely  exceeding  forty- 
five  or  forty-six  beats  in  a minute.  Three  or  four  hours  after  a 
meal,  an  irresistible  desire  obliged  her  to  take  off  the  lint  and 
compresses  with  which  she  covered  the  fistulous  opening,  and 
to  give  vent  to  the  food  which  her  stomach  might  happen  to  con- 
toin;  it  came  out  rapidly,  and  there  escaped  at  the  same  time, 


OF  DIGESTION?. 


11^ 

and  with  a noise,  a certain  quantity  of  gases.  The  food  thus  eva- 
cuated, exhaled  an  insipid  smell,  was  neither  acid  nor  alkaline, 
for,  the  chymous  and  grayish  coloured  pulp  into  which  they 
were  reduced,  when  suspended  in  a certain  quantity  of  distilled 
water,  did  not  effect  vegetable  blues.  The  digestion  of  the  food 
was  far  from  being  always  complete,  sometimes,  however,  the 
smell  of  wine  could  not  be  recognized,  and  the  bread  formed  a 
viscid,  thick  and  soft  substance,  pretty  similar  to  fibrine  newly 
precipitated  by  the  acetous  acid,  and  it  floated  in  a tenacious 
liquid  of  the  colour  of  common  broth. 

It  follows,  from  the  experiments  performed  at  the  Ecole  de 
Medicine,  on  these  half  digested  substances,  and  on  the  same 
before  their  admission  into  the  stomach,  that  the  changes  which 
they  undergo,  consist  in  the  increase  of  gelatine,  in  the  forma- 
tion of  a substance  which  has  the  appearance  of  fibrine,  vvithout 
having  all  its  qualities,  in  a greater  proportion  of  muriate  and 
phosphate  of  soda,  as  well  as  of  phosphate  of  lime. 

This  patient  was  unable  to  sleep,  till  she  had  emptied  her  sto- 
mach, which  she  cleared  by  swallowing  a pint  of  infusion  of 
chamomile.  In  the  morning,  there  was  seen  in  the  empty  sto- 
mach, a small  quantity  of  a ropy  frothy  fluid,  like  saliva.  It  did 
not  turn  vegetable  blues  to  a green  or  red  colour,  was  not  homo- 
geneous, but  exhibited  particles  of  some  degree  of  consistence, 
among  the  more  fluid  parts,  and  even  albuminous  flakes  com- 
pletely opaque.  The  experiments  performed  on  this  fluid,  showed 
that  it  bore  a considerable  analogy  to  saliva,  which,  however,  is 
rather  more  liable  to  putrefaction. 

The  vermicular  motion  by  which  the  stomach  cleared  itself 
of  its  contents,  took  place  in  two  dilferent,  but  not  in  opposite 
directions;  the  one  pressing  the  food  towards  the  fistulous  open- 
ing, the  other  towards  the  pylorus,  through  which  the  smaller 
quantity  was  allowed  to  pass. 

On  opening  the  body,  it  was  found,  that  the  fistula  extended 
from  the  cartilage  of  the  seventh  left  rib,  as  high  as  the  osseous 
termination  of  the  sixth;  its  edges  were  rounded  and  from  three 
to  four  lines  in  thickness;  they  were  covered  with  a thin  moist 
skin,  of  a red  colour,  and  similar  to  that  of  the  lips.  The  peri- 
toneal coat  of  the  stomach  adhered  so  firmly  to  the  peritoneum 
lining  the  fore  part  of  the  abdomen,  around  the  opening,  that 


OF  DIGESTION. 


120 

the  line  of  adhesion  would  not  be  observed.  The  opening  was 
in  the  anterior  part  of  the  stomach,  at  the  anion  of  the  two-thirds 
on  the  left  side,  with  the  third  on  the  right  of  that  viscus;  that 
is  about  eight  fingers’  breadths  from  its  greater  extremity,  and 
only  four  from  the  pylorus.  It  extended  from  the  greater  to  the 
lesser  curvature.  In  other  respects,  it  was  the  only  organic  af- 
fection of  that  viscus. 

It  should  be  stated,  that  for  several  years,  the  patient  had 
been  thin  and  emaciated,  and  had  led  a languid  life,  which 
was  terminated  by  a colliquative  diarrhoea.  She  seemed  to  be 
supported  only  by  the  small  quantity  of  food  which  passed 
through  the  pylorus,  into  the  duodenum,  where  it  received  the 
influence  of  the  bile,  whose  action  on  the  chyme  is,  as  we  shall 
presently  state,  absolutely  essential  to  the  separation  of  the  nu- 
tritious parts.  Not  that  there  was  any  thing  to  prevent  the  absor- 
bents of  the  stomach  from  taking  up  a certain  quantity  of  nutri- 
tious particles,  but  that  small  quantity  of  food,  in  an  imperfect 
condition,  was  of  very  little  service  in  imparting  nourishment, 
and,  in  that  respect,  she  was  in  similar  circumstances  to  patients 
who  are  affected  with  obstruction  of  the  pylorus,  and  reject  the 
greater  part  of  their  food,  when,  digestion  being  over,  this  con- 
tracted opening  can  no  longer  allow  any’  food  to  pass.* 

XXII.  While  the  alimentary  solution  is  going  on,  the  two 
openings  of  the  stomach  remain  perfectly  closed;  no  gas  disen- 
gaged from  the  food,  escapes  along  the  oesophagus,  except  when 
digestion  is  imperfect.  A slight  shivering  is  felt,  the  pulse  be- 
comes quicker,  and  more  contracted,  the  vital  power  seems  to 
forsake  the  other  organs,  to  concentrate  itself  on  that  which  is 
the  seat  of  the  digestive  process.  The  parietes  of  the  stomach 
are  soon  called  into  action;  its  circular  fibres  contract  in  different 
points;  these  peristaltic  oscillations,  at  first  irregular  and  uncer- 
tain, acquire  more  regularity’,  and  act  from  above  downwards, 
and  from  the  left  to  the  right,  that  is  to  say,  from  the  cardiac  to 

* Cases,  in  many  respects,  similar  to  tlie  above,  are  recorded  by  different 
writers. 

Haller,  in  his  “Chirurgical  Dissertations,”  has  the  history  of  a woman  with 
an  aperture  in  her  stomach,  through  which  she  was  nourished  for  tvetiiysei'ea 
years.  For  other  instances  of  fistulous  openings  in  this  viscus,  consult  the  “ Irisk 
Transactions,”  and  “ Medical  Facts  and  Observations.” — Ed. 


OF  DIGESTION. 


121 

the  pyloric  orifice.  Besides,  its  longitudinal  fibres  shorten  it,  in 
the  direction  of  its  greatest  diameter,  and  bring  nearer  to  each 
other  its  own  orifices.  In  these  different  motions,  the  stomach 
rises  over  the,  pylorus,  so  that  the  angle  which  it  forms  with  the 
duodenum,  almost  entirely  ceases,  and  this  facilitates  the  escape 
of  the  food.  It  has  been  observed,  that  during  sleep,  digestion 
takes  place  much  more  readily,  when  we  lie  on  the  right,  than  on 
the  left  side,  and  this  circumstance  has  been  ascribed  to  the  com- 
pression of  the  liver  on  the  stomach.  It  is  much  more  likely  to 
depend  on  the  circumstance,  that  when  we  lie  on  the  right  side, 
the  passage  of  the  food  is  facilitated  by  its  own  weight,  the  na- 
tural obliquity  of  the  stomach,  from  left  to  the  right,  being  in- 
creased, by  the  changes  attending  the  presence  of  the  food. 

XXIII.  On  the  uses  of  the  Pylorus.  The  pyloric  orifice  is 
furnished  with  a muscular  ring,  covered  over  by  a fold  of  the 
mucous  membrane  of  the  stomach.  This  kind  of  sphincter  keeps 
it  perfectly  closed,  while  digestion  is  going  on  in  the  stomach, 
and  will  not  allow  a free  passage  to  the  food  which  has  not  yet 
undergone  a sufficient  change.  The  pylorus,  which  is  endowed 
with  a peculiar  and  delicate  sensibility,  may  be  considered  as  a 
vigilant  guard,  which  prevents  any  thing  from  passing  into  the 
intestinal  canal,  till  it  has  undergone  the  necessary  changes. 
Several  authors  quoted  by  Haller,  have  very  justly  observed, 
that  the  alimentary  substances  do  not  leave  the  stomach  in  the 
same  order  that  they  were  received  into  it,  but  that  they  are 
evacuated  according  to  their  degree  of  digestibility. 

One  may  say,  that  there  really  takes  place  in  the  stomach,  a 
sorting  of  the  different  substances  which  it  contains.  Those  that 
are  most  readily  dissolved,  get  near  to  the  pylorus,  which  ad- 
mits them,  rejecting  those  which,  not  yet  sufficiently  digested, 
cannot  produce  on  it  the  necessary  affection.  To  this  delicacy 
of  tact^  which  I ascribe  to  the  pylorus,  will  be  objected,  per- 
haps, the  passage  it  allows  to  pieces  of  money  and  other  foreign 
indigestible  substances.  But  these  bodies,  which  have  always 
lain  some  time  in  the  stomach  before  they  make  their  way  into 
the  intestines,  repeatedly  attempt  the  orifice  of  the  pylorus,  and 
pass  through,  only  when  they  have  at  last  accustomed  it  to  their 
contact.  The  gastric  system  is  under  the  laws  of  a secretory 

Q 


122 


OF  DIGESTION. 


gland:  and  as  the  roots  of  the  excretory  ducts,  being  endued 
with  a sort  of  elective  sensibility,  will  not  receive  the  secreted 
fluid,  until  it  has  undergone  the  necessary  preparation  in  the 
glandular  parenchyma,  in  the  same  manner,  the  pylorus  admits 
aliments  and  gives  them  passage  into  the  intestines,  which  may 
be  regarded  as  the  excretory  ducts  of  the  stomach,  only  when- 
the}'  have  been  sufficiently  elaborated  by  the  action  of  this  organ. 

XX IV.  As  the  stomach  empties  itself,  the  spasm  of  the  skin 
goes  oflT;  the  shivering  is  followed  by  a gentle  warmth;. the  pulse 
increases  in  fulness  and  frequency;  the  insensible  perspiration  is 
augmented.  Digestion  brings  on,  therefore,  a general  action 
analogous  to  a febrile  paroxysm;  and  this  fever  of  digestion, 
noticed  already  by  the  ancients,  is  particularly  observable  in 
women  of  great  sensibility.  Nothing  positive  can  be  said  on  the 
duration  of  stomachic  digestion;  food  passes  sooner  or  slower 
from  the  stomach,  according  as  its  nature  is  such  as  to  resist, 
more  of  less,  the  actions  which  tend  to  dissolve  it;  according 
too  to  the  strength  and  vigour  of  the  stomach  at  the  time,  and  to 
the  activity  of  the  gastric  juices.  Yet  we  may  state  from  three 
to  four  hours,  as  the  mean  time  of  their  remaining  there.  It  is 
of  consequence  to  know  the  time  required  for  digestion  in  the 
stomach,  that  we  may  not  disturb  it  by  baths,  bleeding,  &c. 
which  would  call  off  towards  other  organs,  those  powers  which 
ought,  at  that  time,  to  be  concentrated  upon  the  stomach. 

If,  as  is  indisputable,  the  stomach  carries  with  it,  into  its  action, 
all  the  other  organs  of  the  economy;  if  it  summons  to  its  aid, 
so  to  say,  the  whole  system  of  the  vital  powers;  if  this  sort  of 
derivation  is  the  more  conspicuous,  as  the  organization  is  more 
delicate,  the  sensibility  more  lively,  the  susceptibility  greater, 
the  importance  is  apparent  of  enforcing  a strict  diet  in  acute  dis- 
eases, and  in  all  cases  where  Nature  is  engaged  in  an  organic 
operation,  which  a little  increase  of  irritation  could  not  fail  to 
disorder,  or  to  break  off.  Those  who  have  practised  in  great 
hospitals,  know  to  how  many  patients  indigestions  are  fatal.  I 
have  seen  some  with  large  ulcers;  suppuration  was  copious  and 
healthy,  the  granulations  fforid,  and  all  promising  a happy  issue, 
when  ignorant  friends  bring  them  by  stealth  indigestible  food, 
with  which  they  cram  themselves,  in  spite  of  the  utmost  watch- 
fulness. The  stomach,  used  to  a mild  and  moderate  regimen. 


OF  DIGESTION. 


123 


at  once  overloaded  with  food,  is  changed  into  a centre  ofjluxion^ 
towards  which  the  juices  and  humours  all  tend;  an  irritation  is 
produced  beyond  that  on  the  ulcerated  surface,  which,  in  a little 
time,  ceases  to  secrete  pus,  the  fleshy  granulations  become  flab- 
by, extreme  oppression  is  felt;  with  a difficulty  of  breathing 
comes  on  a pungent  pain  in  the  side,  the  pain  sympathetically 
felt  in  the  lungs  makes  this  organ  the  seat  of  an  inflammatory 
and  purulent  congestion,  a rattle  ensues,  and  the  patients  die  of 
suffocation,  at  the  end  of  two  or  three  days,  sometimes  in  twen- 
ty-four hours;  and  this  fatal  termination  is  especially  accelerated, 
when,  as  I have  oftened  witnessed,  a blister  is  applied  to  the  seat 
of  the  pain,  instead  of  the  ulcerated  surface. 

It  will  seem  surprising,  perhaps,  that  in  the  case  of  which  I 
have  just  been  speaking,  it  should  be  in  the  lungs,  and  not  the 
stomach  itself,  that  the  congestion  and  the  pain  take  place;  but, 
besides  that  the  most  permeable  organ  of  the  body,  is  the  lungs, 
as  well  as  the  weakest,  and  the  most  easily  yielding  to  Jluxionary 
motion*^  a host  of  instances  prove,  what  a close  sympathy  unites 
it  to  the  stomach.  Let  us  but  call  to  mind  pleurisies  and  bilious 
peripneumonics,  those  acute  pains  of  the  side,  which  since 
Stahl,  physicians  have  so  successfully  treated  with  vomits.  The 
rapidity  with  which  their  symptoms  go  off",  on  the  evacuation  of 
the  sordes  which  oppress  the  stomach,  shows  clearly  that  these 
sympathetic  diseases  are  not  owing  to  the  metastasis  of  bile 
upon  the  lungs,  and  that  they  do  not  consist  in  the  simultane- 
ous existence  of  a gastric  affection,  and  of  an  inflammatory  state 
of  the  pleura  or  of  the  lungs,  but  that  they  are  simple  gastric 
affections,  in  which  the  lungs  are,  at  the  same  time,  the  seat  of 
a sympathetic  pain. 

The  action  of  the  parietes  of  the  stomach  ceases,  only  when 
this  viscus  is  completely  cleared  of  the  food  it  contained.  The 
gastric  juice,  no  longer  secreted,  ceases  to  be  poured  so  freely 
by  its  arteries;  and  the  parietes,  which  close  upon  each  other, 
are  chieflj'^  lubricated  by  the  mucusso  plentifully  secreted  by 
the  inner  coat. 

* Of  all  the  organs  it  is  that  in  which  we  most  meet  with  organic  injury;  and 
those  who  have  opened  many  bodies,  may  have  observed,  how  rare  it  is  to  find 
the  lungs  completely  sound  in  adults  and  in  old  men. 


OF  DIGESTION. 


124 

At  times,  the  action  of  the  muscular  fibres  of  the  stomach 
is  altogether  inverted,  they  contract  from  the  pylorus,  towards 
the  cardia,  and  this  anti-peristaltic  motion,  in  which  the  con- 
tractions are  effected  with  more  force,  more  rapidly,  and  in  a 
manner  really  convulsive,  produces  vomiting.  Then,  the  action 
of  the  abdominal  muscles  is  added  to  that  of  the  stomach;  the 
viscera  are  driven  upwards  and  backwards,  by  the  contraction 
of  the  large  muscles  of  the  abdomen;  the  diaphragm  rises  up 
towards  the  chest.  If  it  sunk  as  it  contracted,  the  ctsophagus, 
which  passes  in  the  interval  of  its  two  crura,  would  be  com- 
pressed, and  the  passage  of  the  alimentary  substances  by  the 
cardiac  orifice  could  not  take  place.  Accordinglv,  it  is  ob- 
served, that  it  is  only  during  expiration  that  any  thing  passes 
frorij  the  stomach  into  the  cesophagus.  Vomiting  may  depend 
upoh  the  obstruction  of  the  pylorus,  on  the  too  irritating  im- 
pression of  any  substance  on  the  coats  of  the  stomach;  it  may 
be  produced  by  the  irritation  of  some  other  organ  with  which 
the  stomach  is  in  sympathy,  &c. 

^ Digestion  in  the  stomach  is  essentially  assisted  by  nervous 
influence.  Many  physiologists,  since  Brunner,  have  found  that 
the  tying  of  the  eighth  pair  of  nerves  (the  pneumo-gastriques) 
provoked  vomiting  and  retarded  the  work  of  digestion.*  As  it 
is  impossible  to  make  this  experiment  without  affecting  respira- 
tion, a function  of  very  different  importance,  it  becomes  difiicult 
to  know,  whether  the  derangement  of  digestion  did  not  proceed 
from  the  general  disturbance  brought  upon  all  the  functions: 
however,  the  brain  does  not  appear  to  be  in  more  immediate  sym- 
pathy with  the  stomach,  than  with  any  other  part  of  the  di- 
gestive tube.  Disgust  from  the  recollection  of  loathed  food  ex- 
cites vomiting.  A more  than  ordinary  exertion  of  the  brain 
relaxes,  disorders,  and  will  even  suspend,  altogether,  the  func- 
tions of  the  stomach:  an  unexpected  piece  of  news,  a violent 
emotion,  are  attended  with  a cessation  of  the  strongest  sensa- 

* Dr.  Haigbton  has  proved,  in  the  most  satisfactoi-y  manner,  that  a ligature 
on  the  eighth  pair  of  nerves,  far  from  inductiig  vomiting,  renders  the  stomach 
incapable  of  rejecting  its  contents,  even  though  excited  by  the  most  power- 
ful emetics.  T. 

See  Memoirs  of  the  London  Medical  Society,  vol.  II.  page  512 . 


OF  DIGESTION. 


125 


tion  of  hunger.  It  would  be  useless  to  bring  together,  in  this 
place,  proofs  of  the  intimate  connexion  subsisting  between  the 
brain  and  the  stomach,  through  the  intervention  of  the  pneumo= 
gastric  nerves,  for  the  connexion  is  questioned  by  no  one. 

XXV.  Of  digestion  in  the  duodenum.  The  food,  on  quitting 
the  stomach,  enters  the  duodenum  and  there  experiences  new 
changes,  as  essential  as  those  Vhich  were  produced  upon  it  by 
digestion  in  the  stomach.  It  might  even  be  said,  that  as  the 
essence  of  digestion  and  its  principal  object  is  the  separation  of 
the  food  into  two  parts,  the  one  recrementitious  and  the  other 
chylous  or  nutritious,  the  duodenum  in  which  that  separation  is 
performed,  is  its  principal  organ.  In  fact,  however  carefully  one 
may  examine  the  grayish  chyme  which  is  sent  out  of  the  sto- 
mach, it  will  be  discovered  to  be  a mere  slimy  homogeneous 
pulp;  and  in  more  than  a hundred  animals  which  I have  opened 
during  the  process  of  digestion,  I never  observed  the  absorbents 
of  the  stomach  filled  with  real  chyle,  like  those  of  the  intestines.* 

* It  is  not  very  long,  since  an  opinion  universally  prevailed  that  the  chyle 
was  fornaed  in  the  stomach.  This  error,  however,  has  been  completely  exposed 
by  the  well  conducted  experiments  of  Fordyce,  Cruikshank,  &c.  &c. 

Digestion  is  rnt  a simple  operation  confined  to  the  stomach  only.  It  is,  on 
the  contrary,  a hig'nly  complicated  function,  consisting  of  a series  of  processes, 
carried  on  chiefly  in  distinct  portions  of  the  alimentary  tube. 

In  the  stomach,  the  previously  masticated  food  is  reduced  by  the  solvent 
quality  of  the  gastric  liquor  into  that  state  which  is  denominated  chyme.  This 
is  the  first  step.  After  reaching  the  duodenum,  this  pultacious  mass  is  gradu- 
ally converted  into  chyle;  hut  by  what  means  so  important  a change  is  effected, 
we  do  not  ^exactly  know.  For  some  time,  physiologists  have  been  content  to 
impute  it  to  a chemical  action,  resulting  from  a combination  of  the  bile  and 
pancreatic  juice  with  the  chyme.  But  unfortunately  for  an  hj"pothesis,  which 
so  conveniently  solved  the  problem,  it  has  of  late  been  shown  by  experiments, 
that  chyle  may  be  produced,  though  the  hepatic,  cystic  and  pancreatic  ducts 
be  tiea.  We,  nevertheless,  are  not  prepared  to  abandon  the  hypothesis.  Before 
implicit  confidence  is  reposed  in  those  experiments,  we  are,  at  least,  entitled 
to  demand  that  they  be  frequently  repeated,  and  with  the  utmost  caution 
av.d  precision,  so  as  to  leave  no  dotibt  of  their  entire  accuracy. 

When  chyle  is  formed,  we  have  hitherto  viewed  the  digestive  process  as 
completed.  May  not,  however,  some  additional  change,  giving  to  the  fluid 
a more  perfect  character,  take  place  in  its  passage  through  the  lacteals  to  the 
blood-vessels?  Considering  the  number  of  conglobate  glands,  which  in  its 
course  act  upon  it,  the  supposition  does  not  appear  altogether  unlikely.  But 
the  change  thus  wrought,  if  any,  must  be  slight,  as  the  chyle,  prior  to  its 
entering  the  lacteals,  is  well  elaborated,  as  is  evident  from  its  having  some 
of  the  leading  properties  of  blood.  It  is  composed  of  three  parts; 


1.  One 


225  OF  DIGESTION. 

The  duodenum  maybe  considered  as  a second  stomach,  very 
distinct  from  the  other  small  intestines,  by  its  situation  exterior 
to  the  peritoneum,  by  its  size  and  by  its  readiness  of  dilatation, 
the  size  and  regularity  of  its  curvatures,  the  great  number  of 
valvulse  conniventes  with  which  its  inner  part  is  furnished,  the 
prodigious  quantity  of  chylous  vessels  which  arise  from  it,  and 
especially  by  its  receiving,  within  its  cavity,  the  biliary  and 
pancreatic  fluids.  If  the  situation  of  the  duodenum  and  the 
peculiarities  of  its  structure  are  attended  to,  it  will  be  readily 
observed,  that  every  thing  in  that  intestine  tends  to  slacken 
the  course  of  the  alimentary  substance,  and  to  prolong  its  stay 
within  it,  that  it  may  remain  the  longer  exposed  to  the  action  of 
these  fluids. 

The  duodenum  is,  in  fact,  almost  entirely  uncovered  by  the 
peritoneum,  a serous  membrane,  which  like  all  those  that  line 
the  inside  of  the  great  cavities,  and  reflect  themselves  over  the 
viscera  which  they  contain,  by  furnishing  them  external  cover- 
ings, admits  but  of  little  extension,  and  seems  to  stretch,  when 
these  viscera  become  dilated,  only  by  the  unfolding  of  its 
numerous  duplicatures.  Fixed  by  a rather  loose  cellular  tissue 
to  the  posterior  side  of  the  abdomen,  the  duodenum  is  suscep- 
tible of  such  dilatation,  as  to  equal  the  stomach  in  size,  as  is 
sometimes  seen  in  opening  dead  bodies.  Its  curvatures  depend 
on  the  neighbouring  organs,  and  seem  almost  invariably  fixed; 
lastly,  numerous  valvulae  line  its  inner  surface,  so  as  to  add  to 
the  friction,  and  to  increase  the  extent  of  surface,  and  thereby 
the  number  of  absorbents  destined  to  take  up  the  chyle  separat- 
ed in  the  duodenum  from  the  excrementitious  part  of  the  food, 

1.  One,  which  maintains  its  fluidity  during  life,  but  coagulates  after 
death,  or  by  exposure  to  the  air.  This  may  be  compared  to  the  Jibrine  of 
the  blood. 

2.  One,  which  resembles  the  serum  of  the  blood  in  continuing  fluid  when 
exposed  to  the  air,  and  in  co.agulating  at  the  same  degree  of  temperature  as 
the  blood.* 

3.  One,  consisting  of  small  globules  analogous  to  those  of  the  blood,  with 
this  difference,  that  they  are  considerably  more  minute. — Ed. 

* The  proportion  of  the  serum  to  the  fibrine  of  the  chyle  is  varied  by  cir- 
cumstances. In  healthy  chyle  there  is  a considerable  quantity  of  fibrine.  When 
the  digestive  organs  are  weak,  it  is  less. 


OF  DIGESTION, 


127 

by  the  action  of  the  fluids  poured  into  it  from  the  united  ducts 
of  the  liver  and  pancreas. 

XXVI.  OJ  the  bile  and  of  the  organs  which  serve  for  its  secre- 
tion. The  bile  is  a viscous,  bitter,  and  yellowish  fluid,  containing 
a great  quantity  of  water,  of  albumen  to  which  it  owes  its  viscid 
condition,  and  oil  to  which  the  colouring  and  bitter  principle  is 
united;  soda,  to  which  the  bile  owes  the  property  of  turning- 
vegetable  blues  to  a green  colour;  phosphates,  carbonates,  and 
muriates  of  soda,  phosphates  of  lime,  and  of  ammonia;  and, 
lastly,  as  some  say,  oxide  of  iron,  and  a saccharine  substance 
resembling  the  sugar  of  milk.  This  fluid,  which  the  ancients 
looked  upon  as  animal  soap,  fitted  for  effecting  a more  intimate 
mixture  of  the  alimentary  matter,  by  combining  its  watery 
with  its  fat  and  oily  parts,  is,  therefore,  extremely  compound: 
it  is  at  once  watery,  albuminous,  oily,  alkaline,  and  saline.  The 
liver  which  secretes  it,  is  a very  bulky  viscus,  situated  in  the 
upper  part  of  the  abdomen,  and  kept  in  its  place  chiefly  by 
its  attachment  to  the  diaphragm,  of  which  it  follows  all  the 
motion. 

The  hepatic  artery,  which  the  cceliac  sends  off  to  the  liver, 
supplies  it  only  with  the  blood  requisite  for  its  nutrition;  the 
materials  of  its  secretion  are  brought  by  the  blood  of  the  vena 
portcE. 

This  opinion  on  the  uses  of  the  hepatic  artery,  which  I take 
up  with  Haller,  cannot  rest  upon  the  experiments  of  those  who 
pretend  to  have  seen  the  secretion  of  the  bile  going  on,  after  it 
was  tied.  Besides  that  the  position  of  this  vessel  makes  the 
operation  almost  impossible,  which  gives  me  reason  to  doubt  if 
ever  it  was  practised, — ^by  intercepting  the  course  of  the  arterial 
blood  carried  to  the  liver,  this  viscus,  even  under  the  received 
hypothesis,  would  remain  deprived  of  nourishment  and  of 
action;  and  the  vena  portse  would  supply  it,  in  vain,  with  a 
blood  on  which  it  could  exert  no  influence.  When  this  vein  is 
tied,  which  is  far  more  easily  done  than  the  artery,  the  secretion 
of  bile  is  seen  to  stop:  but  the  experiment  which  suspends  the 
abdominal  venous  circulation,  is  too  speedily  fatal,  to  justify 
any  conclusive  inference.  It  is  on  analogical  proofs  that  the 
received  hypothesis  rests,  touching  the  manner  of  the  biliary  se- 
cretion. The  hepatic  arterj',  remarkably  lessened  by  the  branches 


128 


OF  DIGESTION. 


it  has  sent  ofF  in  its  way  towards  the  liver,  is  to  that  organ  what 
the  bronchial  arteries  are  to  the  lungs;  and  in  the  same  manner 
the  branches  of  the  vena  portae,  spread  through  its  substance, 
may  be  compared  to  the  system  of  pulmonary  vessels.  It  is  still 
to  be  confessed,  however,  that  the  enormous  bulk  of  the  liver, 
its  being  found  in  almost  all  animals,  and  the  quantity  of  blood 
carried  into  it  by  the  vena  portae,  compared  to  the  small  secre- 
tion there  is  of  bile,  lead  to  the  belief  that  the  blood  sent  to  it 
from  all  the  other  organs  of  digestion,  undergoes  changes  there 
on  which  science  possesses,  as  yet,  no  certain  data,  though  the 
chemists  maintain,  that  the  liver  is,  in  some  short,  the  supple- 
mentary organ  of  the  lungs,  and  assists  in  clearing  the  blood  of 
its  hydrogen  and  carbon. 

The  name  of  vena  porta:  is  given  to  a particular  venous 
system,  inclosed  in  the  abdominal  cavity,  and  formed  as  fol- 
lows: the  veins  which  bring  back  the  blood  of  the  spleen  and 
the  pancreas,  of  the  stomach  and  intestinal  canal,  are  united  in 
a very  large  trunk,  which  ascends  towards  the  concave  face  of 
the  liver,  and  there  divides  into  two  branches.  These  lie  in 
a deep  fissure  in  the  substance  of  this  viscus;  they  send  out, 
through  all  its  thickness,  a multitude  of  branches,  which  divide 
like  arterial  vessels,  and  end,  in  part,  by  opening  into  the  biliary 
ducts  or  pores,  and,  in  part  by  producing  the  simple  hepatic 
veins.  These  veins,  situated  .chiefly  towards  the  convex  or 
upper  surface  of  the  liver,  bring  back,  into  the  course  of  the 
circulation,  the  blood  which  has  not  been  employed  in  the 
formation  of  bile,  and  that  which  has  not  served  to  nourish 
the  substance  of  the  liver:  for,  they  arise  equally  from  the  ex- 
tremities of  the  vena  portae,  and  from  the  extremities  of  the 
ramifications  of  the  hepatic  artery. 

The  liver  differs  from  all  organs  of  secretion,  in  this,  that 
the  materials  of  the  fluid  it  elaborates  are  not  supplied  to  it  by 
its  arteries.  It  should  seem  that  the  bile,  a fat  and  oily  fluid,  in 
which  hydrogen  and  carbon  predominate,  could  be  drawn  only 
from  venous  blood,  in  which,  as  is  known,  these  two  principles 
are  in  superabundance.  The  blood  acquires  the  venous  quali- 
ties, as  it  passes  along  the  circuitious  course  of  the  circulation, 
and  is  supplied  with  hydrogen  and  carbon  the  more  fully,  the 
slower  it  flows.  Now,  it  is  easy  to  see,  that  all  is  naturally 


OF  DIGESTION. 


129 


disposed  for  slackening  the  circulation  of  the  hepatic  blood,  and 
to  give  it,  eminently,  the  distinguishing  properties  of  venous 
blood.  The  arteries  which  furnish  blood  to  the  organs  in  which 
the  vena  portae  rises,  are  either  very  flexuous  as  the  splenic,  or 
frequently  anastomose,  like  the  arteries  of  the  intestinal  tube, 
which  of  all  that  are  in  the  body,  abound  most  in  visible  divi- 
sions and  anastomoses.  It  will  be  seen  in  the  chapter  on  circu- 
lation, how  well  these  dispositions  are  adapted  for  retarding 
the  course  of  the  arterial  blood.  Once  carried  into  the  organs 
of  digestion,  the  blood  stays  there,  whether  it  be  that  the  coats 
of  the  hollow  viscera  being  collapsed  or  closed  upon  themselves, 
hardly  yield  it  passage,  or  that  the  organization  of  some  one  of 
these  viscera  is  favourable  to  its  stagnation. 

The  spleen  seems  to  serve  this  purpose.  Does  this  dingy  and 
soft  viscus,  lodged  in  the  left  hypochondrium,  and  attached  to 
the  great  fundus  of  the  stomach,  receive  the  blood  into  the 
minute  cells  of  its  spungy  parenchyma,  or  does  this  fluid  merely 
traverse,  very  slowly,  the  delicate  and  tortuous  ramifications  of 
the  splenic  vessels?  In  other  respects,  there  is  no  organ  that 
exhibits  more  variety  of  number,  of  bulk,  of  figure,  of  colour, 
and  of  consistence.  Sometimes  manifold,  often  divided  into 
several  lobes  by  deep  clefts;  its  bulk  varies,  not  only  in  different 
individuals,  but  even  in  the  same,  at  different  times  of  the  day, 
as  the  stomach,  full  or  empty,  admits  or  rejects  the  arterial 
blood,  and  compresses  the  spleen  between  its  large  extremity 
and  the  ribs  under  which  it  is  situated,  or  leaves  it  free. 

The  blood  which  fills  the  tissue  of  the  spleen,  blacker,  more 
fluid,  richer  in  oily  principles,  owes  all  these  qualities,  which 
led  the  ancients  to  consider  it  as  a peculiar  substance,  called  by 
them  the  atra  bills  or  black  bile,  to  its  long  protracted  con- 
tinuance within  that  viscus.  The  branches,  which  by  their  union 
form  the  vena  portae,  have  thinner  parietes  than  the  other  veins 
of  the  body,  they  are  not  furnished  with  valves,  and  they  do 
not  readily  free  themselves  of  l;he  blood  which  fills  them.  The 
action  of  these  veins  is,  in  fact,  so  feeble,  that  it  would  not 
suffice  to  enable  them  to  carry  the  blood  onward,  if  the  gentle 
and  alternate  compression  of  the  diaphragm  and  abdominal 
muscles  on  the  viscera  of  the  abdomen  did  not  favour  its  circu- 
lation. On  reaching  the  liver,  the  blood,  which  is  highly  venous, 

R 


130 


OF  DIGESTION. 


is  further  slackened  in  its  circulation,  by  the  increased  ditneH*- 
sions  of  the  space  in  which  it  is  contained,  the  united  caliber  of 
the  branches  of  the  hepatic  vena  portae  exceeding  considerably 
that  of  the  principal  trunk.  Besides,  these  vessels  are  enveloped 
in  the  parenchymatous  substance  of  the  liver,  and  can  act  but 
feebly.  It,  therefore,  circulates  slowly  through  that  organ,  and, 
with  difficulty,  returns  into  the  course  of  circulation.  The 
hepatic  veins,  which  are  of  pretty  considerable  caliber,  and 
without  valves,  remain  constantly  open,  their  parietes  cannot 
close  and  contract  on  the  blood  which  fills  them,  on  account  of 
their  adhesion  to  the  parenchymatous  substance  of  the  liver. 
They  open  into  the  vena  cava,  very  near  the  place  at  which  that 
vein  terminates  into  the  right  auricle.  The  regurgitation  of  the 
blood,  during  the  contraction  of  that  cavity  of  the  heart,  is  felt 
in  the  veins,  and  the  blood  forced  back  towards  the  liver,  is 
exposed  for  a longer  time  to  its  action. 

The  spleen,  therefore,  performs  only  preparatory  functions, 
and  may  be  considered  as  the  auxiliary  of  the  liver,  in  the  se- 
cretion of  the  bile.  It  is  observed,  that  the  quantity  of  the  latter 
increases  after  the  spleen  has  been  extirpated,  and  that  it  is  less 
yellow,  less  bitter,  and  always  imperfect.  The  blood  which 
circulates  in  the  omentum,  is  very  similar  to  that  of  the  spleen; 
I would  even  say,  that  it  contains  oily  particles,  if  the  drops 
which  I have  clearly  noticed  on  its  surface,  might  not  have  come 
from  the  adipose  tissue  of  the  omentum,  which  allows  the  fluid 
contained  in  its  cells  to  flow,  when  a small  puncture  is  made 
into  it,  in  examining  the  blood  contained  in  its  veins. 

The  bile  secreted  in  the  tissue  of  the  liver*  is  absorbed  by 
the  biliary  ducts,  the  union  of  which  forms  the  hepatic  duct. 
The  latter  issues  from  the  concave  surface  of  the  liver,  and 
conveys  the  bile,  either  immediately  into  the  duodenum,  by 
means  of  the  ductus  communis  choledochus,  or  into  the  gall 
bladder.  This  small  membranous  pouch,  which  adheres  by 
means  of  cellular  tissue  to  the  lower  surface  of  the  liver,  is  in 
some  animals  entirely  distinct  from  that  organ,  and  connected 
to  it  only'  by  the  insertion  of  its  duct  into  that  which  comes 
from  the  liver.  Its  inner  membrane  is  soft,  fungous,  plicated, 


See,  in  the  chapter  on  secretion,  the  laws  which  that  function  obeys. 


OP  DIGESTION. 


131 

and  always  covered  with  the  mucus  secreted  by  the  glandular 
criptse  which  it  contains.  This  mucus  defends  the  gall  bladder 
against  the  action  of  the  bile  which  it  coUfeins.  The  almost 
parallel  course  of  the  hepatic  and  cystic  duc^,  the  acute  angle 
at  which  they  meet,  renders  it  difficult  to  account  for  the  passage 
of  the  bile  into  the  gall  bladder.  It  appears,  that  when  the  duo- 
denum is  empty,  the  bile  regurgitates,  in  part,  from  the  hepatic 
duct  into  the  gall  bladder,  collects  within  it,  becomes  thicker 
and  yellower,  and  acquires  a greater  degree  of  bitterness.  Con- 
sequently, the  use  of  the  gall  bladder  is  to  serve  as  a reservoir 
to  a portion  of  the  bile,  which,  remaining  within  it,  is  improv- 
ed in  quality,  acquires  consistence  and  bitterness,  and  is  height- 
ened in  colour,  by  the  absorption  of  its  fluid  parts. 

XXVII.  The  irritation  produced  on  the  parietes  of  the 
duodenum,  when  distended  by  the  chyme,  is  propagated  to  the 
gall  bladder,  by  the  cystic  and  common  ducts.  Its  parietes 
then  contract,  and  oblige  the  bile  to  flow  along  this  cystic  duct 
into  the  ductus  communis  choledochus.  The  pressure  of  the 
distended  intestines  on  the  gall  bladder,  favours  the  excretion 
of  bile.  The  hepatic  bile  is  also  more  abundantly  poured  into 
the  duodenum  during  digestion,  from  being  secreted  in  greater 
quantity  by  the  liver,  which  participates  in  the  irritation  affect- 
ing the  organs  of  digestion,  and  secretes  a greater  quantity. 
The  cystic  and  hepatic  bile,  mixed  in  the  ductus  communis 
choledochus,  undergoes  a change  before  entering  the  duode- 
num, by  uniting  with  the  fluid  of  the  pancreas.  The  excretory 
duct  of  the  pancreas,  a glandular  organ,  which,  in  structure, 
bears  so  great  an  analogy  to  the  parotid  glands,  that  some  phy- 
siologists, assuming  an  identity  of  functions,  have  called  it  the 
abdominal  salivary  gland,  joins  the  biliary  duct,  before  the 
latter  opens  in  the  duodenum,  after  having  insinuated  itself 
obliquely  between  the  coats  of  that  intestine.  It  arises  within 
the  pancreas,  from  a great  number  of  radicles  which  join  it, 
like  the  feathers  of  a quill  to  a common  trunk.  Its  caliber 
increases  in  size,  as  it  approaches  the  large  end  of  the  pancreas, 
situated  on  the  right,  in  the  concavity  of  the  second  curvature 
of  the  duodenum.  Nothing  precise  is  known,  with  regard  to 
the  nature  of  the  pancreatic  fluid;  the  striking  resemblance  of 
the  pancreas  to  the  salivary  glands  leads  to  a presumption,  that 


OF  DIGESTION. 


132 

this  fluid  bears  considerable  analogy  to  the  saliva.  The  quantity 
of  fluid  secreted  by  the  pancreas  is  likewise  unknown,  but  it 
must  be  consider^e,  if  one  may  judge  from  the  great  number 
of  nerves  and  vessels  which  pervade  its  glandular  tissue,  and  its 
quantity  is,  most  probably,  increased  by  the  irritation  of  the 
food  in  the  duodenum. 

This  combination  of  the  united  pancreatic  and  biliary  fluids 
poured  on  the  chyme,  penetrates  it,  renders  it  fluid,  animalizes 
it,  separates  the  chylous  from  the  excrementitious  part,  and 
precipitates  whatever  is  not  nutritious.  In  bringing  about  this 
separation,  the  bile  itself  seems  to  be  divided  into  two  parts,  its 
oily,  coloured,  and  bitter  portion  passes  along  with  the  excre- 
ments, sheathes  them,  and  imparts  to  them  the  stimulating 
qualities  necessary  to  excite  the  action  of  the  digestive  tube. 
Its  albuminous  and  saline  particles  combine  with  the  chyle, 
become  incorporated  to  it,  are  absorbed  along  with  it,  and 
return  into  the  circulation.  There  may,  in  fact,  be  noticed  in  the 
alimentary  mass,  after  it  has-  undergone  this  combination,  two 
very  distinct  parts:  the  one  is  a whitish  milky  substance,  which 
swims  to  the  surface  and  is  the  least  in  quantity;  the  other  is  a 
yellowish  pulp,  in  which,  when  digestion  is  healthy,  it  is  not 
easy  to  recognize  the  nature  of  the  food.  When  the  liver  is 
obstructed,  and  the  bile  does  not  flow  in  sufficient  quantity,  the 
faeces  arc  dry  and  discoloured;  the  patients  are  troubled  with 
obstinate  costiveness,  the  excrement,  uncombined  with  the  bitter 
and  colouring  matter  of  the  bile,  not  proving  sufficiently  irritat- 
ing to  the  Intestinal  canal. 

We  have  just  mentioned  how  the  separation  of  the  chyle  is 
performed;  but  the  mechanism  of  that  separation  and  the  process 
of  chylification  are  absolutely  unknown.  How  does  the  union  of 
the  bile  to  the  chyme  operate,  in  extracting  from  the  latter  the 
recrementitious  part,  and  in  making  it  swim  above  the  rest?  Is 
there  any  connexion  between  that  process  and  the  nature  of  the 
constituent  principles  of  the  bile?  The  knowledge  of  the  compo- 
•sition  of  the  bile,  affords  as  little  assistance  in  the  explanation, 
as  does  the  knowledge  of  the  chemical  properties  of  the  semen, 
in  understanding  the  admirable  function  of  generation.  All 
these  acts  of  the  animal  economy,  are  as  mysterious  and  inex- 
plicable, as  the  action  of  the  brain  in  producing  thought;  a 


6F  DIGESTION. 


135 

phenomenon  which  so  many  physiologists  have  considered  as 
exceeding  the  power  of  matter,  and  for  which  they  seem  to 
have  reserved  all  their  admiration,  though*  mirari,  which 
I would  translate  by  wondering  at  nothings  ought  to  be  the 
motto  of  any  one  who  has  made  some  progress  in  the  study  of 
the  laws  of  life. 

XXVIII.  Of  the  action  of  the  small  intestines.  After  remain- 
ing a certain  time  within  the  duodenum,  the  alimentary  mass 
decomposed  by  the  bile,  or  rather  by  the  pancreatico-biliary 
fluid,  separated  into  two  parts,  the  one  chylous,  the  other 
excrementitious,  passes  into  the  jejunum  and  ileum,  which  are 
not  easily  distinguished  frona  each  other,  and  which  differ  in 
their  relative  length,  according  to  the  elements  on  which  anato- 
mists ground  the  distinction.^ 

The  jejunum  and  the  ileum  alone  occupy  nearly  three-fourths 
of  the  whole  length  of  the  digestive  canal;  they  are  straiter 
than  the  duodenum,  and  do  not  dilate  so  readily,  because  the 
peritoneum,  which  forms  their  outer  covering,  lies  over  their 
whole  surface,  with  the  exception  of  the  posterior  border  at 
which  their  vessels  and  nerves  enter.  It  is  along  that  border, 
that  they  are  fixed  to  the  mesentery,  a membranous  band  form* 
ed  by  a dupUcature  of  the  peritoneum,  which  contains  the 
vessels  and  nerves  going  to  the  jejunum  and  ileum,  which 
prevents  knots  from  forming  in  the  intestines,  and  is  a security 

* The  redness  of  the  parietes  of  the  jejunum,  the  empty  condition  of  that 
intestine,  its  situation  in  the  umbilical  region,  the  great  number  of  its  valvula: 
conniventes,  do  not  distinguish  it  from  the  ileum,  for,  the  colour  of  the  intes- 
tinal canal  varies  in  different  parts  of  its  extent,  and  the  substances  which  fill 
it  are  found  in  different  parts  of  the  canal,  according  to  the  progress  of  diges- 
tion at  the  time  the  parts  are  examined;  according  as  the  convolutions  are 
situated  within  the  cavity  of  the  pelvis,  or  rise  towards  the  eplgastrlo  region; 
according- to  the  full  or  empty  state  of  the  bladder  and  stomach;  and  the 
number  of  circular  folds,  called  valvulse  conniventes,  diminishes  as  one  gets 
near  to  the  termination  of  the  ileum.  Winslow  got  over  the  difficulty,  by  con- 
sidering the  upper  two-fifths  of  the  small  intestines  as  jejunum,  and  the  re- 
maining three-fifths  as  ileum.  This  last  division,  from  measurement,  is  wholly 
arbitrary,  and  is  besides  useless,  far  there  is  not,  perhaps,  above  one  occasion 
in  which  it  would  be  interesting  to  distinguish  the  jejunum  from  the  ileum- 
In  operating  for  hernia,  when  the  intestine  is  mortified,  one  would  decide  the 
more  readily  to  leave  an  artificial  anus,  if  one  could  be  sure  that  the  gangre- 
nous portion  belonged  to  the  latter  intestine;  but  of  this  it  is  absolutely  im- 
possible  to  be  certain. 


®F  DIGESTION. 


against  the  occurrence  of  intus-susceptio.  It  is  well  known, 
however,  that  in  some  rare  cases,  intus-susceptio  does  take 
place,  with  the  utmost  danger  of  the  patient’s  life,  who  gene- 
rally dies  in  the  agonies  of  insufferable  colic  pains,  which 
Slothing  can  alleviate.  The  progress  of  the  food,  along  the 
small  intestines,  is  retarded  by  its  numerous  curvatures,  very 
aptly  compared  by  some  physiologists  to  the  windings  of  a 
meandering  stream  which  fertilizes  the  soil  it  waters.  These 
numerous  convolutions  of  the  intestinal  canal  favour  the  long 
continued  presence  of  the  food  within  its  cavity,  so  that  the 
chyle  expressed  from  the  excrementitious  part  by  the  peristaltic 
contractions  of  the  intestine,  may  present  itself  to  the  inhaling 
mouths  of  the  lacteals,  by  which  it  is  to  be  absorbed.  These 
chylous  absorbents  are  in  greatest  number  on  the  surface  of  the 
valvulse  conniventes,  which  are  circular  folds  of  the  inner  mem- 
brane, and  these  are  at  a greater  distance  from  each  other,  the 
nearer  they  are  to  the  termination  of  the  ileum.  The  valvulae 
conniventes  not  only  slacken  the  progress  of  the  food,  but  by 
their  projections,  they  sink  during  the  contraction  of  the  bowels, 
into  the  alimentary  mass,  and  the  lacteals  on  their  surface  take 
up,  from  its  inmost  part,  the  chyje  which  they  are  destined  to 
absorb. 

The  number  of  the  valvulse  conniventes  diminishes  with  that 
of  the  lymphatics.  The  progress  of  the  alimentary  substance  is 
gradually  accelerated,  as  it  parts  with  its  nutritive  and  recremen- 
titious  particles.  A quantity  of  mucus,  secreted  by  the  internal 
membrane  of  the  small  intestines,  envelops  the  chymous  mass 
and  promotes  its  progress,  by  lubricating  it;  this  intestinal  mu- 
cus thrown  out  by  the  exhalent  arteries  imbues  it,  renders  it 
liquid  and  adds  to  its  bulk. — This  fluid,  which  seems  to  partake 
of  the  nature  of  albumen  and  gelatine,  and  to  hold  several  sa- 
line substances  in  solution,  is,  for  the  greater  part,  recrementi- 
tious,  and  must  be  very  considerable  in  quantity,  if  we  may 
judge  from  the  caliber  of  the  mesentric  arteries,  and  from  the 
extent  of  the  internal  surface  of  the  intestines.  It  is,  however, 
scarcely  possible,  that  this  exhalation  should  amount  to  eight 
pounds  in  twenty-four  hours,  according  to  Haller’s  calculation, 
who,  as  we  shall  observe,  when  we  treat  of  the  secretions,  has 
generally  over-rated  their,  amount. 


OF  DIGESTIOJT, 


135 

The  peristaltic  contractions,  by  the  assistance  of  which  the 
alimentary  mass  is  sent  along  the  whole  course  of  the  small  intes- 
tines, do  not  occur  in  a regular  and  uninterrupted  succession, 
from  the  stomach  to  the  caecum.  This  undulatory  and  vermicu- 
lar motion  manifests  itself  at  once,  in  several  points  of  the  length 
of  the  tube,  whose  curvatures  straighten  themselves  at  intervals. 
In  this  action,  the  intestinal  curves  are  decomposed  into  a great 
number  of  short  straight  lines  which  meet  so  as  to  form  obtuse 
angles.  The  peristaltic  motion  which  affects  the  muscular  fibres 
of  the  intestines,  is  caused  by  the  irritation  of  the  alimentary 
substance  on  the  sentient  parietes  of  the  canal  along  which  it 
descends  towards  the  great  intestines.  The  jejunum  and  the 
ileum,  covered  by  the  peritoneum,  except  at  the  part  which  con- 
nects them  to  the  mesentery,  at  the  time  of  dilatation,  separate 
the  two  peritoneal  laminae,  forming  the  mesentery.  They  occupy 
the  space  between  the  branches  of  the  mesenteric  vessels,  whose 
last  division  is  always  at  some  distance  from  the  adhering  edge 
of  the  intestine.  If  this  division  of  the  vessels  had  taken  place 
nearer  to  the  union  of  the  intestine  and  mesentery,  the  intestinal 
canal  would  not  have  admitted  of  dilatation,  without  stretching 
the  vessels  situated  at  the  angle  of  separation.  It  is  likewise  ob- 
served, that  in  the  portions  of  the  digestive  tube  which  are  most 
susceptible  of  dilatation,  the  last  vascular  divisions  are  most  dis- 
tant. Hence  the  left  gastro-epiploic  artery  is  always  at  a greater 
distance  from  the  great  curvature  of  the  stomach  than  the  right, 
a circumstance  of  which  no  anatomist  has  hitherto  taken  notice. 

XXIX.  Of  digestion  in  the  great  intestines.  The  alimentary 
mass,  after  it  has  parted  with  nearly  the  whole  o'f  its  nutritive 
particles,  passes  from  the  ileum  into  the  cascum;  it  then  is  re- 
ceived into  the  great  intestines,  which  are  more  spacious,  though 
shorter,  than  the  small,  forming  scarcely  a fifth  of  the  whole 
length  of  the  digestive  tube. 

A musculo-membranous  valvular  ring  is  placed  at  the  oblique 
insertion  of  the  ileum  into  the  first  of  the  great  intestines.  This 
valve,  called  after  Eustachius  or  Bauhinus,  who  are  considered 
as  its  discoverers,  though  the  merit  of  the  discovery  belongs  to 
Fallopius,  is  formed  of  two  semi-circular  segments,  the  right 
edge  of  which  is  free  and  floats  towards  the  cavity  of  the  csecum. 
The  more  the  parietes  of  that  intestine  are  distended  by  the  sub- 


OF  DIGESTION. 


136 

stances  which  it  contains,  the  greater  is  the  difficulty  to  the  re- 
trograde flow  of  such  substances,  for  under  those  circumstances, 
the  two  extremities  of  the  valve  are  at  a distance  from  each 
other,  and  its  edges,  which  are  free,  close  on  each  other,  like 
those  of  a button  hole  whose  angles  are  drawn  in  opposite  di- 
rections; besides,  the  muscular  fibres  which  enter  into  its  struc- 
ture render  it  capable  of  exerting  constriction.  It  is,  therefore, 
calculated  to  permit  the  ready  flow  of  matter  from  the  ileum 
into  the  caecum,  and  forcibly  prevent  their  return  into  the  small 
intestines.  There  are  facts  which  lead  to  a belief,  that  its  resist- 
ance is  sometimes  overcome,  and  that  a clyster,  thrown  in  with 
violence,  would  force  the  valve  and  be  thrown  up  by  vomiting. 
The  great  intestines  may  be  considered  as  a kind  of  reservoir 
destined  to  contain,  for  a certain  time,  the  excrementitious  re- 
sidue of  our  solid  aliments,  so  as  to  save  us  the  disgusting 
inconvenience  of  constantly  parting  with  it. 

As  the  peritoneum  does  not  wholly  cover  the  great  intestines, 
they  are  capable  of  considerable  dilatation,  and  of  extending 
into  the  cellular  substance  which  connects  them  to  the  posterior 
part  of  the  abdomen.  Their  muscular  coat  which,  in  a manner, 
is  the  base  of  the  intestinal  tube,  does  not  consist  throughout 
of  circular  and  longitudinal  fibres.  The  latter,  collected  into 
fasciculi,  form  three  narrow  bands,  in  the  intervals  of  which 
the  parietes  of  the  gut  are  exceedingly  weakened,  and  conse- 
quently capable  of  greater  extension.  These  longitudinal  fibres 
being,  besides,  shorter  than  the  intestine,  crease  it  transversely, 
and  form  within  it  a number  of  cavities  and  cells,  marked  out- 
wardly by  prominences  separated  by  depressions.  If,  in  addi- 
tion to  these  peculiarities  of  structure,  it  be  considered  than  in 
the  CEecum  and  a great  part  of  the  colon,  the  contents  of  the 
bowels  have  to  ascend  against  their  own  weight;  that  the  cur- 
vature forming  the  sigmoid  flexure  of  the  colon  is  very  conside- 
rable, and  that,  in  short,  the  rectum,  before  its  outer  termina- 
tion in  a narrow  aperture,  is  considerably  dilated,  it  will  be 
evident,  that  in  the  great  intestines,  every  thing  tends  to  pro- 
tract the  stay  of  the  excrements. 

The  appendicula  vermi-formis  of  the  caecum  is,  in  man,  too 
small  to  perform  this  office;  in  the  herbivorous  quadrupeds,  in 
which  it  is  much  larger,  and  sometimes  not  single,  it  may  serve 


OF  DIGESTION. 


13T 

as  a reservoir  to  the  fecal  matter.  Its  existence  merely  shews  in 
man,  an  analogy  to  those  animals  in  which  it  is  truly  useful,  and 
it  concurs  in  manifesting,  that  Nature,  in  the  formation  of  par- 
ticular organs,  in  certain  kinds  of  animals,  aims  at  a mere  out- 
line, which  she  fills  up  in  others,  to  shew,  as  it  were,  that  there 
are  points  of  resemblance  between  all  beings  whom  she  has  gifted 
with  life  and  motion. 

While  in  the  great  intestines,  the  alimentary  substance  be- 
comes merely  fecal,  by  parting  with  the  small  quantity  of  chyle 
which  it  may  yet  contain.  The  number  of  the  absorbents  decreases 
progressively  from  the  caecum  to  the  rectum.  The  small  number 
of  these  vessels,  accounts  for  the  difficulty  of  throwing  in  nou- 
rishment by  means  of  clysters,  when  there  is  an  obstruction  to 
deglutition. The  excrements  thicken,  harden,  and  become 
formed  or  moulded,  in  the  cells  of  the  colon,  they  are  then 
urged  by  the  peristaltic  action  into  the  rectum,  in  the  cavity  of 
which  they  accumulate,  till  they  excite  on  its  parietes  an  action 
which  determines  their  expulsion. 

XXX.  Of  the  evacuation  of  the  fceces.  When  a call  to  eva- 
cuate the  feces  is  experienced,  the  rectum  contracts,  while  the 
diaphragm  descending,  and  the  abdominal  muscles  receding 
towards  the  spinef,  thrust  the  viscera  of  the  abdomen  towards 
the  cavity  of  the  pelvis,  and  compress  the  intestines  which  are 
filled  with  fecal  matter.  During  these  efforts,  the  perineum  per- 
ceptibly descends,  and  the  fibres  of  the  levator  ani  are  somewhat 

* This  is  one,  but  not  the  only  reason,  why  the  system  cannot  be  sustained 
for  any  length  of  time  by  injections.  For  the  formation  of  chyle,  containing  the 
elements  of  blood,  which  it  always  does  when  genuine,  it  is  indispensably  ne- 
cessary that  the  aliment  should  be  previously  converted  into  chyme,  an  opera- 
tion which  seems  from  experiments,  cannot  be  effected  in  the  great  intes- 
tines.— Ed. 

■j-  Some  physiologists  have  considered  as  unnecessary,  this  concurrent  action 
of  the  diaphragm  and  abdominal  muscles;  they  ground  their  opinion  on  the 
circumstance,  that  animals  whose  abdomen  has  been  laid  open  are  capable  of 
voiding  their  faeces.  Astruc,  one  of  the  luminaries  of  Montpellier,  denies  the 
action  of  the  abdominal  muscles,  in  the  efforts  which  one  makes  at  stool,  and 
in  support  of  his  opinion,  he  brings  forward  his  geometrical  proposition,  “ that 
a cord  disposed  in  the  form  of  a circle,  can,  by  contracting,  shorten  itself  in  an 
infinitely  small  degree,  and,  therefore,  not  perceptibly.”  On  which  Pitcairn, 
humorously  enough  observes,  that  Astruc  had  never  practised  what  he  rea- 
sons upon:  " credo  Astruccium  nunquam  cacasse'* 


138 


OF  DIGESTION. 


elongated.  The  combined  action  of  the  rectum  and  of  the  abdo- 
minal muscles,  overcomes  the  resistance  of  the  sphincters,  and 
the  alvine  evacuation  takes  place,  and  is  facilitated  by  the  secre- 
tion of  the  mucous  follicles  of  the  rectum:  these  glands,  squeez- 
ed by  the  pressure  of  the  faeces,  pour  out  their  contents  and 
lubricate  the  circumference  of  its  lower  aperture.  When  the 
faeces  have  been  voided,  the  diaphragm  rises,  the  large  muscles 
of  the  abdomen  cease  to  press  backwards  and  downwards  upon 
the  viscera  of  that  cavity;  the  perineum  ascends  and  the  sphinc- 
ters close,  till  a renewal  of  the  same  call,  again  brings  on  the 
same  action. 

The  call  to  void  the  faeces,  is  more  frequent  in  children  than 
in  adults,  because,  at  an  early  period  of  life,  tbe  sensibility  of 
the  intestinal  canal  is  greater,  tbe  contents  of  the  bowels  more 
fluid,  and  digestion  more  active.  As  we  advance  in  years,  sen- 
sibility becoming  impaired,  and  contractility  experiencing  a pro- 
portionate loss  of  power;  the  secretions  being,  likewise,  less 
abundant,  the  bowels  become  sluggish,  the  stools  more  scanty 
and  indurated.  They  are,  likewise,  less  frequent  and  copious  in 
women  than  in  men,  whether  it  be,  that  the  digestive  power  ex- 
tracts from  the  aliment,  a greater  proportion  of  nutritious  mat- 
ter, or  that  the  menstrual  evacuation  being  a kind  of  substitute 
for  the  intestinal  secretions,  less  remains  to  add  to  the  bulk  of 
the  excrementitious  mass.  The  evacuation  of  the  faeces,  may  be 
brought  on  by  throwing  liquids  into  the  rectum,  which  dilute 
the  faeces,  detach  them  from  the  parietes  of  the  intestines,  and, 
exciting  on  these  parietes  an  irritation  to  which  they  are  not  ac- 
customed, determine  their  contraction. 

The  fetor  of  the  excrements  depends  on  their  incipient  pu- 
trefaction in  the  great  intestines.  This  decomposition  is,  almost 
always,  attended  with  the  extrication  of  gases,  in  which  sul- 
phuretted hydrogen  prevails.  This  gas,  which  at  times  escapes, 
and  which  at  others  impregnates  the  faeces,  is  the  cause  of  the 
black  colour  which  they  give  to  silver  exposed  to  their  action. 
One  may  recognize  in  the  excrements,  the  colouring  matter  of 
vegetables,  such  as  the  green  colour  of  spinage,  the  red  of  beet 
root;  one  may,  likewise,  find  among  them,  the  fibrous  parts  of 
plants  and  animals,  the  indurated  bark,  and  the  seeds  covered 
with  their  husks.  The  digestive  juices  have  so  little  action  on 


OF  DIGESTION. 


139 


husks,  that  seeds  which  have  not  been  broken  down  by  the  or- 
gans of  mastication,  frequently  continue  capable  of  vegetation. 

During  the  progress  of  digestion,  the  food  contained  in  the 
stomach  and  intestines  absorbs  or  extricate  different  gases.  M. 
Jurine,  of  Geneva,  opened  the  body  of  a maniac  who  had  been 
dead  a few  hours,  and  collected  the  gases  which  escaped;  he  ob- 
served, that  the  proportion  jif  oxygen  and  carbonic  acid  dimi- 
nishes from  the  stomach  towards  the  great  intestines,  while,  on 
the  contrary,  there  is,  in  these,  an  increased  proportion  of  azote; 
that  hydrogen  is  more  abundant  in  the  great  than  in  the  small  in- 
testines, that  it  is  less  in  quantity  in  these  than  in  the  stomach. 
Do  the  oxygen  and  azote  form  a part  of  the  atmospherical  air 
which  is  taken  in  with  the  food  and  with  the  saliva,  and  which 
is  disengaged  by  the  heat  of  the  intestinal  canal?  Or  are  these 
gases  the  result  of  the  decomposition  of  the  food  and  of  the  in- 
testinal fluids?  Besides,  may  not  the  gas  contained  in  the  intes- 
tines of  a dead  body,  have  been  formed  at  the  moment  of  death? 
We  know  that,  in  several  instances,  at  the  moment  contractility 
is  forsaking  our  organs,  the  intestines  become  distended  by  gas, 
which  hastens  the  approach  of  death,  by  impeding  the  descent  of 
the  diaphragm. 

Digestion,  when  healthy,  is  unaccompanied  by  the  production 
of  gases.  In  indigestion,  there  almost  always  escapes  carbonated 
or  sulphuretted  hydrogen  gas,  which  produces  the  offensive  smell 
of  the  air  which  escapes  at  the  anus;  this  smell  is  different  from 
that  of  the  flatus  which  are  brought  upwards;  these  contain  pure 
hydrogen  or  carbonic  acid  gas.  The  latter  is,  likewise,  some- 
times voided  by  the  rectum,  but  less  frequently  than  hydrogen 
combined  with  carbon,  sulphur,  or  even  phosphorus.  Is  not  am- 
monia itself  extricated,  and  does  it  not  accompany  the  evacua- 
tion of  the  fasces  in  certain  putrid  diarrhoeas,  as  in  dysentery 
combined  with  low  fever?  Though  the  formation  of  this  gas  im- 
plies a putrefactive  motion  opposed  to  the  vital  principle,  may 
not  this  decomposition  commence  in  substances  lying  in  the 
great  intestines,  when  these  are  become  almost  inert  from  the 
impaired  condition  of  the  vital  power.  This  would  not  be  the 
only  instance  of  a chemical  process  taking  place  in  the  intestinal 
canal,  notwithstanding  the  counteracting  influence  of  vitality. 
Thus,  on  some  occasions,  grapes  eaten  in  too  great  quantity,  fer- 


OF  DIGESTION. 


140 

ment  and  produce  carbonic  acid  gas,  in  such  abundance,  that  this 
elastic  fluid  overcomes  the  resistance  of  the  intestines.  This  is 
the  kind  of  distention  from  flatulence  which  is  cured  by  drinking 
plentifully  of  cold  water,  which  dissolves  the  gas  naturally  solu- 
ble in  that  fluid.* 

XXXI.  Of  the  secretion  and  excretion  of  the  urine.  The  fluids 
absorbed  with  the  chyle,  and  taken  up  bv  the  lymphatics  of  the 
intestinal  tube,  dilute  the  nutritive  part  extracted  from  the  solid 
aliment,  and  serve  it  as  a vehicle.  When  they  have  reached  the 
mass  of  the  blood,  they  increase  its  quantity,  diminish  its  visci- 
dity and  render  it  more  fluid;  going  along  with  it  throughout 
the  whole  course  of  the  circulation,  they  supply  moisture  to  all 
the  parts  of  the  body,  and  become  loaded  with  the  molecules  de- 
tached from  them  by  the  vital  motion.  Then,  conveyed  to  the 
urinary  organs,  they  become  disengaged  from  the  rest  of  the 
fluids,  carrying  along  with  them  a number  of  products  of  every 
kind,  which  by  a longer  stay  in  the  animal  economy,  would  not 
fail  to  occasion  a manifest  disturbance  in  the  exercise  of  the 
functions. 

XXXil.  The  rapidity  with  which  we  void,  with  the  urine, 
certain  diuretics,  has  induced  several  physiologists  to  think,  that 
there  exists  a direct  communication  between  the  stomach  and 
bladder;  no  one,  however,  has  ever  succeeded  in  pointing  out 
those  peculiar  ducts,  which  might  serve  to  convey  the  urine  from 
the  stomach  to  the  urinary  organs,  without  taking  the  circuitous 
course  of  absorption  and  of  the  circulation;  and,  besides,  the 
learned  Haller  has  proved,  by  accurate  calculations,  that  the  size 
of  the  renal  arteries,  whose  caliber  amounts  to  an  eighth  of  that 

* It  is  now  well  ascertained,  that  no  gas  is  extricated  in  healthy  digestion. 
In  morbid  conditions  of  this  function,  however,  it  does  occasionally  happen. 
But  I do  not  agree  with  the  author  in  thinking  “ill  formation  implies  a putre- 
factive motion  opposed  to  the  vital  principle.”  It  may  result  from  some  chemi- 
cal changes  in  the  alimentary  substances,  but  it  is  more  probable  that  the  gas, 
in  these  instances,  is  the  product  of  secretion. 

By  Mr.  Hunter  it  has  been  shown  very  satisfactorily,  that  gas  is  often  se- 
creted by  the  vessels  of  animal  bodies,  or  in  other  words,  as  we  suspect, 
that  a matter  is  eliminated,  wliich  has  such  an  affinity  for  caloric,  as  to  as- 
sume the  gaseous  state.  This  matter  would  seem  to  be  carbon,  as  the  gas 
evolved,  at  least  in  colic,  is  carbonic  acid,  reddening  the  tincture  of  turnsole, 
and  making  lime  water  turbid. — Ed. 


OF  DIGESTIOH’. 


of  the  aorta,  and  the  quickness  with  which  the  blood  flows,  suf- 
ficed to  account  for  the  shortness  of  the  time  in  which  certain 
fluids  reach  the  urinary  organs. 

A thousand  ounces  of  blood  pass  through  the  renal  tissue  in 
the  space  of  an  hour:  supposing  that  this  fluid  contains  only  a 
tenth  of  the  materials  fit  for  supplying  urine,  a hundred  ounces, 
or  seven  pounds  and  a quarter,  may  be  given  out  in  this  short 
time;  and  never,  with  the  most  copious  and  diuretic  drinks,  does 
more  of  it  pass  in  an  hour.  We  shall  see,  however,  in  treating 
of  absorption,  that  it  is  not  absolutely  impossible,  that  by  means 
of  the  numerous  anastomoses  of  the  lymphatics,  this  set  of  vessels 
may  carry  a liquid  directly  from  the  stomach  into  the  bladder. 
It  would  be  superfluous  to  mention,  in  this  place,  the  varieties 
observable  in  the  kidneys,  in  point  of  number,  size,  and  situation. 
These  two  lobular  viscera,  composed  of  the  union  of  from  twelve 
to  fifteen  glandular  bodies,  divided  in  the  fostus,  and  in  some 
quadrupeds,  attached  to  the  posterior  part  of  the  abdomen,  be- 
hind the  peritoneum,  are  surrounded  with  a cellular  covering  of 
different  thickness,  and  particularly  remarkable  by  the  con- 
sistence, approaching  to  that  of  tallow,  of  the  fat  which  fills 
its  cells. 

If  ever  the  art  of  man  shall  penetrate  into  the  mystery  of  the 
intimate  structure  of  our  organs,  it  seems  probable  that  the  kid- 
neys will  furnish  the  first  solution  of  the  problem.  Even  coarse 
injections  pass  readily  from  the  renal  arteries  into  the  ureters, 
or  excretory  ducts  of  the  kidneys;  a convincing  proof  of  imme- 
diate communication  among  the  minute  arteries,  which,  exceed- 
ingly tortuous,  form,  with  the  minute  veins,  the  cortical  or  out- 
ward substance  of  the  kidneys,  and  the  straight  urinary  tubes, 
which,  distributed  in  conical  fasciculi,  in  the  interior  of  these 
organs,  constitute  what  has  been  called  its  tubuli  and  papillae. 
The  passage  of  injections  from  the  arteries  into  the  renal  veins, 
is  as  easy;  and  I have  often  seen  the  coarsest  liquids  flowing  at 
once  by  the  ureters  and  by  the  emulgent  veins.  This  free  commu- 
nication between  the  arteries,  the  veins,  and  excretory  ducts  of 
the  kidneys,  gives  an  idea  of  the  rapidity  with  which  the  blood 
must  flow  through  these  organs,  whose  firm  consistence  allows 
a very  moderate  dilatation  to  the  vessels;  and  suggest  the  pos- 
sibility of  a sort  of  filtration  of  the  urinary  fluid,  the  secretion  of 


OF  DIGESTION. 


142 

which  would  be  only  a succession  of  chemical  or  mechanical  se- 
parations from  the  blood,  in  its  passage  along  very  minute  ducts, 
of  a bore  progressively  decreasing.  This  was  the  opinion,  at 
least,  of  Ruysch,  whose  system  on  the  intimate  composition  of 
our  organs,  and  on  the  immediate  continuation  of  the  blood- 
vessels with  the  excretory  ducts,  is  chiefly  founded  on  the  facts 
of  structure,  discovered  to  him  by  his  beautiful  injections  of  the 
renal  arteries. 

The  kidneys  are  of  duller  sensibility  and  less  energetic  action 
than  the  other  glands.  The  force  of  life  had  less  to  do  in  their 
secretion,  and  their  functions  may  be  more  readily  explained  on 
the  principles  of  chemistry  or  hydraulics. 

XXX HI.  If  we  attempt,  indeed,  to  apply  to  the  urinary  or- 
gans the  fundamental  laws  on  the  mechanism  of  secretions,*  it 
is  soon  seen,  that  these  organs  are  not  under  their  absolute  con- 
trol. Of  all  the  animal  fluids,  urine  is  the  one  most  complex  in 
its  elements,  and  most  variable  in  its  qualities.  Not  only  do  fo- 
reign substances  sometimes  appear  in  it,  afiect,  and  even  change 
its  composition;  other  fluids  may,  at  times,  mix  with  it,  and  dis- 
guise it  altogether.  Thus  credible  observers  tell  us  of  the  ap- 
pearance in  urine,  of  bile,  fat,  milk,  blood,  pus,  of  which  many 
facts  may  be  found  collected  in  Haller’s  great  work  on  physio- 
logy. The  kidneys,  then,  have  less  sensibility  than  the  other  se- 
cretory organs:  they  reason  less,  if  I may  venture  on  the  ex- 
pression, on  the  sensation  produced  by  the  various  substances  in 
the  blood:  their  action  is  also  less  powerful;  it  does  not  so  inti- 
mately affect  the  fluid  subjected  to  it.  It  does  not  change  the 
heterogeneous  qualities  of  those  that  are  mixed  with  it,  and  al- 
lows them  to  pass  in  a pure  state. 

This  multitude  of  elements  in  the  composition  of  urine,  had 
surely  been  understood  by  the  ancients,  before  it  was  demon- 
strated by  modern  chemistry;  for  they  considered  it  as  a sort  of 
extract  of  animal  substance,  as  a real  lixivium,  carrying  off  all 
that  is  impure  in  the  economy,  and  gave  it  the  name  of  lotiutriy 
which  indicates  that  destination. 

Finally,  the  secretion  of  urine  is  more  uniformly  carried  on: 
it  is  continual,  or  at  least,  does  not  exhibits©  prominently  those 


See  the  chapter  on  Secretiom 


OP  DIGESTION. 


145 

alterations  of  action  and  repose,  so  apparent  in  the  work  of  the 
other  secretory  organs.  When,  in  a case  of  retention  of  urine, 
we  introduce  a catheter  into  the  urinary  bladder,  and  leave  it 
there,  the  urine  keeps  dropping  continually,  and  would  wet  the 
patient’s  bed,  if  the  orifice  of  the  catheter  was  not  kept  closed. 
In  the  memoirs  of  the  Academy  of  Sciences  for  the  year  1761, 
there  is  related  a case  of  singular  comformation  of  the  urinary 
bladder.  This  musculo-membranous  viscus  protruded  through 
an  opening  at  the  lower  part  of  the  linea  alba,  and  was  turned 
inside  out,  so  as  to  present,  externally,  its  mucous  membrane. 
This  case  afforded  an  opportunity  of  observing  the  continual 
flow  of  the  urine  through  the  orifices  of  the  ureters,  and  of  as- 
certaining the  different  circumstances  attending  this  process, 
either  with  regard  to  the  qualities  of  this  fluid,  or  to  the  quan- 
tity which  might  be  voided,  in  a certain  space  of  time,  and  in 
this  respect  there  was  a good  deal  of  difference,  according  to 
the  state  of  sleep  and  waking,  to  the  quantity  and  to  the  diuretic 
qualities  of  the  drink. 

The  urine  contained  in  the  ureters  is  turbid  and  imperfect}  its 
constituent  parts  are  not  thoroughly  blended  together,  as  may 
be  observed,  if  made  to  flow,  by  compressing  the  kidneys  in  a 
dead  body.  It  improves  by  passing  along  those  duct,  acquires 
the  characteristic  qualities  of  urine,  oozes  at  the  surface  of  the 
papillas,  and  flows  into  the  membranous  calices  which  embrace 
the  rounded  terminations  of  the  tubuli  uriniferi.  The  union  of 
the  calices  forms  the  pelvis,  or  the  expanded  portion  of  the 
ureters,  or  membranous  ducts,  along  which  the  urme  is  inces- 
santly flowing  into  the  bladder.  The  urine  flows  into  the  bladder 
by  its  own  weight,  and  especially  by  the  action  of  the  parietes  of 
the  ureters,  which  possess  a certain  degree  of  contractility.  To 
the  above  causes,  may  be  added  the  concussions  excited  by  the 
pulsations  of  the  renal  arteries,  behind  which  the  pelvis  of  the 
kidney  is  situated,  and  by  the  pulsations  of  the  iliac  arteries,  in 
front  of  which  the  ureter  passes,  before  entering  the  cavity  of  the 
pelvis;  the  alternate  compression  from  the  viscera  of  the  abdo- 
men, during  the  motions  of  respiration;  the  concussion  attend- 
ing bodily  exercise,  as  riding  on  horseback,  walking,  running, 
&c.;  the  pressure  of  the  column  of  urine  from  the  kidneys,  and 
tlte  want  of  resistance  towards  the  bladder. 


OP  DIGESTION. 


144 

XXXIV.  The  urine  is  continually  passing,  in  drops,  into  the 
bladder,  it  separates  its  parietes,  without,  however,  exciting  in 
them  any  perceptible  impression,  as  they  are  accustomed  to  its 
Stimulus.  The  urine  cannot  accumulate  in  the  musculo-membra- 
nous  cavity  of  the  bladder,*  which  is  situated,  exterior  to  the 
peritoneum,  in  the  cavity  of  the  pelvis,  behind  the  pubis,  above 
which,  in  the  adult,  it  never  rises,  except  when  excessively  dis- 
tended, unless  it  is  prevented  from  flowing  along  the  urethra,  or 
from  returning  by  the  ureters.  This  retrograde  flow  is  prevented 
by  the  oblique  insertion  of  these  ducts,  which  pass,  for  some  dis- 
tance, between  the  muscular  and  mucous  coats  of  the  bladder, 
before  opening  within  it,  towards  the  posterior  angles  of  the 
trigone  vesical,t  by  openings  of  smaller  dimensions  than  their 
cavity.  The  inner  coat  of  the  bladder,  raised  over  these  aper- 
tures, gives  them  the  appearance  of  being  provided  with  valves, 
which  fit  the  better  these  orifices,  according  as  the  urine  con- 
tained in  the  bladder,  by  separating  its  parietes,  presses  against 
each  other  the  coats  by  which  they  are  formed,  and  between 
\yhich  the  ureters  pass,  along  a space  of  from  seven  to  eight  lines. 

The  urine  which  flows  into  the  bladder,  requires  a certain  de- 
gree of  force  to  separate  its  parietes  on  which  the  weight  of  the 
intestines  presses.  This  is  cflFected  by  no  other  power  than  by 
that  which  causes  the  flow  of  the  urine  along  the  ureters,  and 
though  inconsiderable,  it  will  appear  sufiicient,  if  it  be  considered 

• In  the  numerous  tribe  of  birds,  the  bladder  is  wanting.  In  them,  the  ureters 
open  into  the  cloaca,  a musculo-membranous  bag,  which  supplies  the  place  of 
the  rectum,  bladder,  and  uterus,  and  which  serves  as  a reservoir  to  the  solid 
excrements,  to  the  urine,  and  to  the  eggs  detached  from  the  ovaria.  The  urine 
of  birds  dilutes  the  faeces  and  furnishes  the  carbonate  of  lime  which  forms 
the  basis  of  the  egg  shell.  It  has  such  a tendency  to  concretion,  that  I have 
always  observed,  in  dissecting  various  fowls  of  different  kinds,  an  earthy,  sa- 
line or  crystallized  substance,  forming  white  striae  easily  seen  in  the  fluid  of  the 
ureters,  through  their  thin  and  transparent  coats.  Hence  one  may  readily  con- 
ceive, how  frequently  calculi  would  form  in  these  animals,  if  their  urine  accu- 
mulated and  remained,  for  any  lengtli  of  time,  stationary  in  a cavity  destined  to 
contain  it. 

f The  French  anatomists  give  the  name  of  trigone  tiesical,  to  that  portion  of 
the  bladder  included  between  the  openings  of  the  ureters  and  the  neck  of  the 
bladder,  and  forming  a triangle,  whose  base  is  represented  by  a line  drawn 
from  the  opening  of  one  ureter  to  the  other,  and  whose  apex  is  situated  at  the 
insertion  of  the  urethra  into  tlie  neck  of  the  bladder.  T, 


OF  DIGESTION. 


145 

that  the  fluids  which  pass  from  a strait  channel  into  a larger  ca- 
vity, act  on  every  superficial  portion  of  its  parietes  equal  to  the 
area  of  the  channel,  with  a power  equal  to  that  which  determines 
their  flow  into  the  latter;  so  that  if  the  urine  descends  along  the 
ureters,  with  a degree  of  force  equal  to  one,  and  if  the  inner  sur- 
face of  the  bladder  is  a thousand  times  more  extensive  than  the 
area  of  the  ureters,  the  power  will  be  multiplied  a thousand  fold. 

This  purely  mathematical  proposition  is  expressed  by  saying, 
that  the  force  with  which  the  urine  passes  along  the  ureters,  is 
to  that  by  which  the  parietes  of  the  bladder  are  distended,  as  the 
caliber  of  the  ureters  is  to  the  superfices  of  the  bladder. 

The  pressure  which  the  urine,  accumulated  within  the  bladder, 
exerts  on  the  lower  part  of  the  ureters,  does  not  prevent  the 
force  which  determines  its  descent  along  the  ureters,  from  car- 
rying it  into  the  bladder: — for,  the  column  which  descends  along 
the  ureters,  being  higher  than  that  contained  in  the  bladder, 
these  two  organs  represent  an  inverted  syphon,  the  longer  branch 
of  which  is  represented  by  the  ureter. 

The  following  are  the  causes  which  enable  the  bladder  to  rcr 
lain  the  urine:  the  contraction  of  its  sphincter,  a muscular  ring 
surrounding  the  termination  of  the  urethra  into  the  bladder:  the 
angle  formed  by  that  canal,  after  it  leaves  the  bladder:  and  lastly, 
the  action  of  the  anterior  fibres  of  the  levator  ani,  which  sur- 
round the  neck  of  that  organ,  surrounded  besides  and  supported 
by  the  prostate  gland.  These  fibres,  which  are  calculated  to  com- 
press the  prostate  over  the  neck  of  the  bladder,  and  to  raise  the 
latter  against  the  pubis,  have  been  called  by  Morgagni,  pseudo 
sphincteres  vesicce. 

The  urine,  deposited  by  drops  into  the  bladder,  gradually  se- 
parates its  parietes.  This  musculo-mernbranous  organ  rises,  and 
at  the  same  time,  carries  upwards  the  convolutions  of  the  ileum, 
and  the  peritoneum  before  which  it  lies,  behind  the  pubis  and 
the  recti  muscles  with  which  it  is  in  immediate  contact.  These 
relations  of  the  peritoneum  to  the  distended  bladder,  account  for 
the  possibility  of  puncturing  it  above  the  pubis,  so  as  to  let  out 
an  accumulation  of  urine,  without  penetrating  into  the  cavity  of 
the  peritoneum. 

The  urine  remains  a certain  time  in  the  bladder,  according  to 
the  capacity  of  the  latter,  to  the  irritability  and  extensibility  of 

T 


146 


OF  DIGESTION. 


its  parietes,  and  according  to  the  acrid  or  stimulating  qualities 
of  the  fluid  itself.  Thus  in  old  men,  in  whom  the  bladder  has  but 
a small  degree  of  irritability  and  contractility,  the  urine  is  voided 
less  frequently;  it  accumulates  in  greater  quantity,  and  is,  at 
times,  evacuated  with  difficulty.  The  use  of  diuretics,  especially 
of  cantharides,  renders  the  urine  more  stimulating,  it  excites 
powerfully  the  parietes  of  the  bladder  and  incessantly  stimulates 
it  to  contraction.  Every  cause  of  irritation  seated  within  the 
bladder  itself,  or  in  its  vicinity,  renders  more  frequent  the  calls 
to  void  urine.  This  is  observed  in  cases  of  stone  in  the  bladder, 
of  piles,  gonorrhcea,  &c.  The  urine,  while  in  the  bladder,  be- 
comes thicker  from  the  absorption  of  its  more  fluid  parts,  its  ele- 
ments become  more  intimately  blended,  sometimes  even  it  ap- 
pears to  undergo  a certain  degree  of  decomposition. 

XXXV.  When,  either  by  the  extension  which  the  urine  oc- 
casions in  the  muscular  fibres  of  the  bladder,  or  by  the  irritation 
which  it  excites  in  the  nerves  distributed  on  its  inner  membrane, 
we  experience  in  the  pelvis  a sensation  of  weight,  together  with 
a kind  of  tenesmus,  which,  as  it  extends  along  the  urethra,  warns 
us  to  void  urine;  then  we  bring  on  a contraction  of  the  bladder, 
and  joining  to  its  action  that  of  the  abdominal  muscles  and  of 
the  diaphragm,  we  expel  the  urine  by  a process  very  similar  to 
that  of  the  excretion  of  the  faeces  (XXIX).  It  should  be  ob- 
served, however,  that  in  a healthy  state  of  the  parts,  this  assist- 
ance is  required,  only  to  overcome  the  equilibrium  between  the 
contractions  of  the  bladder,  and  the  resistance  which  the  cause 
of  retention  opposes  to  the  evacuation  of  the  urine.  After  the 
simultaneous  contraction  of  the  diaphragm  and  abdominal  mus- 
cles, to  press  down  the  intestines  on  the  bladder,  and  to  deter- 
mine the  first  flow  of  the  urine,  we  cease  that  effort,  and  the 
bladder  alone,  still  supported  by  the  weight  of  the  surrounding 
viscera,  which  compress  it  as  it  empties  itself,  completes  the  eva- 
cuation. We  repeat  the  first  effort,  only  in  case  w^e  wish  to  ac- 
celerate the  flow  of  the  urine.  In  the  evacuation  of  the  faeces,  on 
the  contrary,  the  muscular  coat  of  the  rectum  requires  the  in- 
cessant co-operarion  of  the  respiratory  powers,  as  these  solid 
substances  are  evacuated  with  more  effort  than  the  urine.  To 
prove,  beyond  a doubt,  that  the  urine  is  evacuated,  chiefly  by 
the  action  of  the  bladder,  one  need  but  observe  the  violent,  but 


OF  DIGESTION, 


147 

useless  straining  of  patients  affected  with  retention  of  urine, 
from  paralysis  of  the  bladder.^ 

The  urine  is  projected  along  the  urethra  with  the  greater  force, 
as  it  passes  from  a spacious  cavity  into  a strait  canal,  and  it  is 
expelled  with  a force  proportioned  to  that  of  the  muscular  coat 
of  the  bladder;  we  know,  that  in  old  men,  this  is  so  weak,  that 
the  jet  of  urine  is  not  projected  more  than  a few  inches  beyond 
the  urethra.  The  urethra  is  not  to  be  considered  as  inert  in  the 
evacuation  of  the  urine;  it  closes  upon  it  and  accelerates  its  flow, 
aided  in  that  action  by  the  bulbo-cavernous  muscles  to  which 
several  anatomists  have  given  a name  taken  from  their  functions, 
(acceleratores  urince). 

The  action  of  these  muscles  expels  the  last  drops  of  urine 
which  remain  within  the  urethra,  when  the  bladder  is  completely- 
emptied.  The  contractile  and  tonic  action  of  the  urethra  is  so 
distinctly  marked,  that  its  spasmodic  contraction  may  be  enume- 
rated among  the  causes  which  frequently  occasion  a difficulty 
in  introducing  the  catheter.  If  we  attempt  to  inject  fluids  along 
the  urethra,  the  moment  we  remove  the  pipe  of  the  syringe 
which  closes  its  external  orifice,  that  instant  the  parietes  of 
the  canal  contract  on  the  fluid  and  expel  it  with  a rapid  jet. 

The  bladder  and  the  canal  of  the  urethra  are  lined  internally 
with  a membrane,  whose  mucous  follicles  secrete  a viscid  hu- 
mour calculated  to  protect  the  parietes  of  these  organs  against 
the  action  of  the  urine,  and  to  facilitate  the  evacuation  of  that 
fluid.  This  membr^e,  whose  surface  is  more  extensive  than 
the  cavities  whicluit  lines,  forms  a great  number  of  folds,  which 
disappear  when  the  bladder  is  distended  with  urine.  This 
mucus  is  secreted,  in  an  unusual  quantity,  in  catarrhal  affections 
of  the  bladder,  and  becomes,  likewise,  more  ropy  and  more  al- 
buminous. The  mucous  secretion  of  the  glands  of  the  urethra 
is  altered  in  its  quality,  and  becomes  more  abundant,  from  the 
action  of  the  venereal  poison,  and  gives  rise  to  the  discharge  of 

* It  is  scarcely  credible  that  some  physiologists  should  have  considered  this 
organ  as  inert  and  absolutely  passive,  in  the  evacuation  of  the  urine,  -which,  in 
their  opinion,  is  performed  by  the  immediate  pressure  of  the  abdominal  mus- 
cles  and  diaphragm  on  that  cavity.  Amid  this  variety  of  opinions,  if  you  wish  to 
come  at  the  truth,  you  must  take  a medium.  lUacos  intrd  muros  peccatur,  et 
extrd. 


OF  DIGESTION. 


148 

gonorrhaa;  the  orifices  of  these  lacunae  may  stop  the  end  of  a 
catheter,  so  as  to  add  to  the  difficulty  of  introducing  that  in- 
strument*. 

The  urine  cannot  be  voided  at  the  same  time  as  the  faeces, 
when  these,  by  their  hardness,  compress  the  prostatic  and  the 
membranous  part  of  the  urethra,  situated  before  the  lower  ex- 
tremity of  the  rectum.  It  is  difficult,  and  often  impossible  to 
void  urine,  during  a violent  erection,  as  the  parietts  of  the 
canal  are  then  closely  applied  to  each  other,  by  the  turgescence 
of  the  corpus  spongiosum  and  of  the  corpora  cavernosa ' <t'  the 
penis.  The  mode  of  sensibility  of  the  urethra  is  besides  chang- 
ed in  such  a manner,  that  it  is  calculated  to  permit  only  the 
emission  of  the  seminal  fluid. 

When  the  bladder  is  completely  emptied,  it  sinks  behind  the 
pubis;  the  tumour  which  is  formed  above  these  bones,  while  in 
a state  of  distention,  collapses,  the  abdomen  becomes  less  pro- 
minent, respiration  more  free,  and  there  is  a general  feeling  of 
lightness.  The  bladder  cannot  be  completely  evacuated,  unless 
the  pelvis  is  gently  inclined  forward;  its  has  fond^  which  is  on  a 
lower  level  than  its  neck,  would,  in  any  other  posture,  retain  a 
certain  quantity  of  urine. 

XXXVI.  Of  the  physical  properties  of  urine.  As  this  fluid 
varies  in  quantity  in  a healthy  man,  according  to  the  quantity 
and  diuretic  qualities  of  the  drink,  the  state  of  sleep  or  waking, 
the  condition  of  the  secretions,  and  especially  of  the  perspira- 
tion, it  is  very  difficult  to  determine,  accurately,  its  proportions. 
Nothing  varies  more  than  its  quantity,  as  may  be  ascertained, 
by  comparing  the  different  calculations  on  that  subject,  of  a 
great  number  of  physiologists.  At  times,  the  urine  is  less  in 
quantity  than  the  drink  that  has  been  taken  in;  at  others,  more. 

♦when  this  operation  is  performed  in  a case  of  simple  paralysis  .of  the 
bladder,  it  is  better  to  employ  a very  large  catheter,  which  may  stretch  the 
parietes  of  the  urethra,  and  prevent  tlieir  forming  into  wrinkles,  and  whose 
rounded  beak  may  not  get  engaged  in  the  lacunse  of  that  canal. 

When  in  a case  of  retention  of  urine,  the  bladder  rises  above  the  pubis,  its 
tas  fond  is  carried  upwards,  and  there  is  a period  of  excessive  distention,  at 
which,  like  the  uterus  in  an  advanced  state  of  pregnancy,  it  seems  to  make 
an  effort  to  rise  above  the  brim  of  the  pelvis;  under  such  circumstances  in 
women,  it  is  impossible  to  introduce  the  catheter,  except  by  increasing  the 
curve  of  the  instrument 


OF  DIGESTION. 


149 


It  may  be  affirmed,  however,  that  the  quantity  of  urine  voided 
in  twemy-four  hours,  is  equal  to  that  of  the  insensible  perspira- 
tion in  the  same  time,  and  it  may,  therefore,  be  estimated  at 
between  three  and  four  pounds,  ia  a healthy  adult,  its  colour 
varies,  from  a light  lemon  yellow,  to  an  orange,  approaching  to 
red.  Its  smell  and  flavour  are  peculiar,  and  distinguish  it  from 
everv  other  animal  fluid.  Its  colour  is,  in  general,  darker,  its 
smell  and  flavour  stronger  and  more  pungent,  as  it  is  less  in 
quantity,  as  the  circulatory  system  is  more  active  and  powerful, 
and  as  the  substances  of  our  food  are  more  animalizcd.  We  all 
know  how  fetid  and  how  scanty  is  the  urine  of  carnivorous  ani- 
mals; how  offensive  to  the  sn^ell  is  that  of  the  cat!  The  specific 
gravity  of  urine  is  greater  than  that  of  distilled  water,  and 
varies  according  to  the  quantity  of  saline  and  other  substances 
which  it  holds  in  solution;  it  is,  likewise,  slightly  viscid,  but  not 
ropy  like  the  serum  of  the  blood,  the  bile,  the  saliva,  and  other 
albuminous  fluids. 

XXXVII.  Of  the  chemical  properties  of  urine.  The  peculiar 
qualities  of  urine  are  always  more  marked  in  a powerful  and 
adult  male,  than  in  children,  women,  and  weakly  persons.  By 
chemical  analysis,  the  urine  is  found  to  contain  eleven  substan- 
ces, dissolved  in  a considerable  quantity  of  water,  viz.  urea,  a 
gelatinous  animal  matter,  muriates  and  phosphates  of  soda  and 
ammonia,  in  separate  or  in  triple  salts,  phosphate  of  lime,  phos- 
phate of  magnesia,  phosphoric,  uric,  and  benzoic  acids.  Be- 
sides these  substances  which  are  constantly  found  in  human 
urine,  this  fluid  may  contain  a great  number  of  others;  and  if 
it  be  true  that  the  urinary  system  is  to  be  considered  as  the 
emunctory  of  the  whole  economy,  one  would  expect  to  find  in 
it,  in  certain  proportions  and  under  different  circumstances,  the 
whole  of  the  constituent  principles  which  analysis  has  hitherto 
discovered  in  our  solids  and  liquids.  Hence,  doubtless,  the 
difference  in  the  results  obtained  by  the  chemists  who  have  in- 
vestigated the  nature  of  the  urine,  by  allowing  it  to  run  into 
decomposition,  or  by  applying  to  it  various  re-agents. 

As  the  urine  is,  of  all  our  fluids,  that  which  has  the  greatest 
tendency  to  putrefaction.  It  should  be  examined  shortly  after 
being  voided;  it  is  then  distinctly  acid,  but  in  a very  short  time, 
and  especially  if  the  heat  of  the  atmosphere  promotes  and  ac- 


OF  DIGESTION. 


150 

celerates  these  changes,  it  becomes  turbid,  its  component  parts 
separate  and  form  various  precipitates.  Urea  and  gelatine, 
which  alone  of  its  constituent  principles  are  capable  of  fermen- 
tation and  decomposition,  give  out  ammonia,  acetous  and  carbo- 
nic acids,  and  from  the  chemical  attraction  between  these  newly 
formed  substances,  and  from  the  primitive  elements,  there  are 
produced  new  compounds  the  knowledge  of  which  is  of  the 
department  of  chemistry. 

Of  all  the  constituent  parts  of  urine,  the  most  essential  is  a 
substance  of  the  consistence  of  syrup,  deliquescent,  susceptible 
of  crystallization,  to  which  M.  Fourcroy  has  given  the  name  of 
urea.  This  substance,  to  which  the  urine  owes  its  characteristic 
properties,  its  peculiar  colour,  smell  and  flavour,  which  was 
imperfectly  known  to  several  chemists  who  had  sketched  some 
of  its  features,  giving  it  different  names,  according  to  the  notions 
they  entertained  of  its  nature,  was  never  well  understood  till 
the  late  investigations  of  this  celebrated  professor^.  It  is  a 
compound  in  which  azote  prevails,  as  is  shewn  by  the  im- 
mense quantity  of  carbonate  of  ammonia,  which  it  gives  out  in 
distillation;  it  may  be  considered  as  the  most  animalized  pro- 
duct, having  such  a tendency'  to  the  putrid  fermentation,  that, 
even  while  in  the  animal  economy,  it  is  liable  to  that  decompo- 
sition, and  might  overcome  the  antiseptic  influence  of  the  vital 
power,  if  nature  did  not  get  rid  of  it  by'  the  evacuation  of  the 
urine. 

Sufficient  attention  has  not  hitherto  been  paid  to  the  sy’mp- 
toms  of  urinary  fever,  an  affection  occasioned  by  the  protracted 
retention  of  the  urine  within  the  bladder.  I have  observed,  on 
several  occasions,  that  no  kind  of  fever  is  attended  with  more 
marked  signs  of  what  physicians  term  putridity.  The  urinous 
and  ammoniacal  smell  exhaled  from  the  body  of  the  patients, 
the  yellowish  and  oily  moisture  of  their  skin,  the  parching  thirst 
with  which  they  are  tormented,  the  dryness  and  redness  of  their 
tongue  and  throat,  their  frequent  and  irritable  pulse,  combined 
with  a flaccid  and  doughy  feel  of  the  cellular  tissue,  every -thing 
indicates  that  the  animal  frame  is  threatened  with  the  most 
speedy  and  dangerous  decomposition. 

* See  his  work  entitled:  Systeme  des  connaissances  chimiques.  8vo.  tom.  x. 
page  153. 


OP  DIGESTION. 


151 

I observed  similar  appearances  in  a cat  and  in  a rabbit,  in 
which  1 tied  the  ureters.  Nothing  is  easier  than  to  find  the  ure- 
ters and  to  perform  this  experiment.  After  a crucial  incision  of 
the  parietes  of  the  abdomen,  on  the  left  side,  the  intestines  are 
pushed  aside  to  the  left,  so  as  to  apply  a ligature  on  the  right 
ureter,  they  are  then  pushed  to  the  right,  while  the  left  ureter 
is  tied.  Both  ureters  are  seen  through  the  peritoneum,  situated 
behind  that  membrane,  in  the  lumbar  region.  When  the  liga- 
tures have  been  applied  to  the  ureters  about  their  middle, 
the  divided  edges  of  the  abdomen  are  brought  together  and 
united  by  sutures,  and  the  body  of  the  animal  is  wrapped  round 
with  a cloth  soaked  in  some  emollient  decoction.  At  the  end  of 
six  and  thirty  hours,  the  animals  became  exceedingly  thirsty  and 
restless,  their  eyes  glistening;  their  saliva,  which  flowed  copi- 
ously, exhaled  a smell  evidently  urinous;  on  the  third  day,  the 
cat  was  seized  with  vomiting  of  a slimy  substance,  remarkable 
by  its  having  the  same  smell.  This  convulsive  agitation  was 
followed  by  an  excessive  prostration  of  strength;  it  died  on  the 
fifth  day;  the  intestines  were  not  inflamed,  the  bladder  quite 
empty,  the  ureters  distended  with  urine  between  the  ligatures 
and  the  kidneys,  and  as  large  as  the  ring  finger.  The  kidneys 
themselves,  gorged  with  urine,  were  turgid,  softened,  and  as  if 
macerated.  All  the  organs,  all  the  fluids,  the  blood  itself,  par- 
took of  this  urinous  diathesis;  putrefaction  came  onimmediately 
after  death,  and  at  the  end  of  a few  days,  an  almost  complete 
decomposition  of  the  body  had  taken  place.  In  the  rabbit  the 
symptoms  were  less  violent  and  rapid;  it  did  not  die  till  the 
seventh  day;  the  smell  of  its  whole  body,  though  evidently  uri- 
nous, was  less  offensive,  and  the  putrefaction  which  succeeded 
was  less  rapid. 

These  two  experiments  confirm,  in  the  first  instance,  what 
some  authors  have  said  of  the  absence  of  urine  in  the  bladder, 
when  the  ureters  have  been  tied;  an  undeniable  proof  that  these 
are  the  only  channels  which  convey  the  urine  into  the  bladder; 
they  likewise  concur  in  affording  the  most  convincing  proof, 
that  the  kidneys  are  the  emunctories  by  means  of  which  the 
blood  clears  itself  of  that  part  of  it  which  is  animalized  in  ex- 
cess; finally,  they  prove,  that  the  retention  of  this  fluid  is  the 


J52  DIGESTIO&\ 

more  dangerous  to  the  animal  economy,  as  the  urine  is  itself 
more  animalized. 

Has  nature  the  means  of  supplying  the  evacuation  of  urine 
by  other  excretions?  might  this  highly  recrementitious  fluid  be, 
without  danger,  evacuated  by  other  emunctories?  With  a view 
to  answer  this  interesting  question,  the  kidneys  have  been  ex- 
tirpated in  dogs.  The  removal  of  one  kidney,  did  not  prevent 
the  secretion  from  being  carried  on;  in  every  case  in  which 
both  kidneys  were  removed  at  once,  the  animal  died  in  a few 
days,  and  on  opening  the  body,  there  was  uniformly  found  a 
considerable  quantity  of  bile  in  the  gall  bladder,  in  the  small 
intestines,  and  even  in  the  stomach,  as  if  the  urea  had  endea- 
voured to  make  its  escape  in  that  direction,  by  combining  with 
the  bile.  These  experiments  were  performed  at  the  Hopital 
Saint  Louis,  in  the  course  of  the  year  XL 

Urea,  combined  with  a certain  quantity  of  oxygen,  appears  to 
form  an  acid  peculiar  to  human  urine,  and  which  is  the  sub- 
stance of  the  greater  number  of  urinary  calculi.  It  resembles 
urea  in  this,  that  its  crystals,  exposed  to  heat,  give  out  carbonate 
of  ammonia;  but  it  differs  essentially  from  it,  by  its  ready  con- 
crescibility.  It,  in  fact,  crystallizes  every  time  the  urine  grows 
cold,  and  forms  the  greatest  part  of  the  urinary  sediment — 
This  acid,  so  weak  that  several  chemists  have  considered  it  to 
be  a mere  oxide,  has  been  called  by  M.  M.  Fourcroy  and 
Vauquelin,  the  uric  acid.  Among  its  distinguishing  characters, 
may  be  mentioned  its  being  insoluble  in  cold  water;  it  is  so  fix- 
ed, that  several  thousand  times  its  own  weight  of  boiling  water 
16  required  to  dissolve  it:  hence  it  may  be  easy  to  account  for 
its  so  frequently  giving  rise  to  urinary  calculi;  we  may,  indeed, 
wonder,  that  this  complaint  is  not  of  more  frequent  occurrence, 
since  a slight  cooling  of  the  urine  is  sufficient  to  cause  a preci- 
pitation and  crystallization  of  the  urine.  Thus,  every  time  an 
extraneous  substance  drops  into  the  bladder,  it  becomes  the 
nucleus  of  a calculus,  formed  by  the  uric  acid  becoming  concrete 
on  the  surface  of  this  body,  which  of  a colder  temperature. 
Quadrupeds  are  less  frequently  affected  with  urinary  calculi, 
from  the  absence  of  the  uric  acid  in  their  urine,  and  because  car- 
bonate of  lime,  of  which,  in  those  animals,  such  concretions  ai'e 


OF  DIGESTION; 

formed,  is  a salt  deeomposed  with  cfifervesGence  by  the  weaker 
acids,  and  several  such  acids  are  found  in  the  urine. 

Phosphorus,  which  may  be  considered  as  the  result  of  a high 
degree  of  animalization,  enters,  in  considerable  proportions, 
into  human  urine.  Besides  the  phosphoric  salts  which  it  con- 
tains, there  is  always  found  a certain  quantity  of  disengaged 
phosphoric  acid,  which  holds  in  solution  the  calcareous  phos- 
phate, and  gives  to  the  urine  its  manifest  acidity,  when  examin- 
ed fresh,  or  shortly  after  it  has  been  voided.  It  was  from  urine 
that  phosphorus  was  first  obtained  by  those  who  originally  dis- 
covered it,  and  from  that  fluid  it  has  long  been  procured  for 
the  purposes  of  commerce.  But  it  is  seldom  obtained  from  urine, 
since  the  discovery  of  the  phosphoric  acid  in  the  earth  of  bones 
has  rendered  the  manufacture  of  phosphorus  easier  and  less  ex- 
pensive. In  the  urine  of  frugivorous  mammiferous  animals,  phos- 
phoric salts  have  their  place  supplied  by  calcareous  carbonate. 

Certain  substances  impregnate  the  urine  with  a peculiar  odour. 
It  is  well  known,  that  if  one  remain  a few  minutes  in  a room 
newly  painted  with  oil  of  turpentine,  the  urine,  for  some  time 
afterwards,  gives  out  a smell  of  violets;  asparagus  gives  to  the 
urine  a very  remarkable  fetor. 

XXXVIII.  Besides  the  accidental  varieties  observed  in  the 
urine,  varieties  which  cannot  be  determined,  since  the  urine  is 
never  uniformly  tflesame  in  its  composition,  and  does  not  con- 
tain the  same  ingredients  in  the  same  person,  at  different  times 
of  the  day,  according  to  the  quantity  and  quality  of  the  food  and 
drink,  the  exercise  which  has  been  taken,  the  affections  of  the 
mind  which  have  been  experienced,  &c.;  it  constantly  varies, 
according  to  the  time  which  has  elapsed  since  a meal,  the  age 
of  the  subject  and  the  diseases  under  which  he  may  labour. 

Physiologists  have,  for  a long  while,  admitted  two  and  even 
three  different  kinds  of  urine,  according  to  the  time  at  which  it 
is  voided;  they  are  distinguished  by  the  names  of  urine  of  the 
drink,  urine  of  the  chyle,  and  urine  of  the  blood.  The  first  is  a 
limpid  and  nearly  colourless  fluid,  which  frequently  retains,  in 
a remarkable  manner,  the  qualities  of  the  drink,  and  is  voided 
shortly  after  drinking,  and  has  scarcely  one  of  the  characters  of 
perfect  urine.  The  urine  of  the  chyle  or  of  digestion,  voided 
two  or  three  hours  after  a meal,  is  more  formed,  still  it  is  not 

U 


OF  DIGESTION. 


154 

perfect  and  does  not  contain  all  the  component  parts  of  this  fluid. 
Lastly,  the  urine  of  the  blood,  which  is  voided  seven  or  eight 
hours  after  a meal,  and  in  the  morning  after  the  night’s  rest, 
contains,  in  an  eminent  degree,  all  the  qualities  of  urine;  hence 
it  is  that  which  chemists  prefer  using  in  their  analysis.  The  im- 
perfect state  of  the  two  former  kinds  of  urine,  would  prove 
better  than  the  rapidity  of  their  secretion,  the  disputed  existence 
of  a peculiar  communication  from  the  stomach  and  intestines 
into  the  bladder. 

The  urine  of  children  and  that  of  nurses  contains  very  little 
phosphate  of  lime  and  phosphoric  acid;  it  is  only  after  the  pro- 
cess of  ossification  is  completed,  that  these  elements  abound  in 
the  urine.  That  of  old  men,  on  the  other  hand,  contains  a 
considerable  quantity  of  these  substances;  their  osseous  system 
already  containing  phosphate  of  lime  in  excess,  and  incapable  of 
receiving  more,  this  saline  substance  would  ossify  all  the  tissues, 
as  it  sometimes  does  that  of  the  arteries,  the  ligaments,  the  car- 
tilages and  membranes,  if  the  urine  did  not  carry  off  the  greater 
part. 

In  the  rickets,  it  is  by  the  urine  that  the  phosphate  of  lime  is 
carried  out  of  the  system,  and  the  absence  of  that  substance  is 
the  cause  of  mollities  ossium;  on  the  approach  of  fits  of  the  gout, 
the  phosphoric  ingredients  of  the  urine  diminish  and  seem  to 
be  carried  to  the  joints,  to  produce  in  their  vicinity  arthritic 
concretions. 

The  great  quantity  of  saline  and  crystallizable  elements  which 
enter  into  human  urine,  accounts  for  the  frequency  of  the  con- 
cretions which  form  in  that  fluid.  Urinary  calculi  were  long  con- 
sidered as  formed  of  a single  substance*  which  the  ancients 
thought  analogous  to  the  earfh  of  the  bones,  and  which  Scheele 
took  for  uric  acid.  The  late  investigations  of  M.  M.  Fourcroy 
and  Vauquelin  have  shown,  that  the  component  parts  of  urine 
are  too  numerous  and  too  complex  to  produce  uniformly  calculi 
of  one  kind:  that  urinary  concretions,  most  frequently  formed 
from  uric  acid,  contain  urate  of  ammonia,  phosphate  of  lime, 
phosphate  of  ammonia  and  magnesia,  oxalate  of  lime,  silex;  and 
that  these  substances,  singly,  or  in  binary  and  ternary  combi- 
nations, form  the  materials  of  nearly  six  hundred  calculi  which 
they  analysed.  Notwithstanding  the  extent  of  these  researches, 


or  DIGESTION. 


155 

there  is  reason  to  believe,  that  when  carried  further  by  the  same 
chemists,  they  will  be  attended  with  results  still  more  varied. 
For,  as  there  is  no  integral  molecule  in  the  body  which  may  not 
be  voided  with  the  urine,  and  be  found  in  the  urine,  so  it  is  con- 
ceivable, that  under  certain  circumstances  which  it  is  impossible 
to  assign  or  to  foresee,  every  thing  in  the  human  body  that  is 
capable  of  concretion,  might  supply  the  materials  of  urinary 
concretions. 

This  variety  of  elements  in  the  composition  of  urinary  calculi, 
the  absence  of  signs  by  which  to  ascertain  their  nature,  the  sen- 
sibility of  the  parietes  of  the  bladder  which  would  be  irritated 
by  agents  capable  of  dissolving  the  concretions  so  frequently 
formed  in  its  cavity,  must  render  it  very  difficult,  not  to  say  im- 
possible, to  discover  a lithontriptic  which  should  supersede  the 
necessity  of  a surgical  operation,  whose  difficulties  and  danger 
have  been  much  over-rated. 

XXXIX.  The  energy  of  the  urinary  system  in  the  inhabi- 
tants of  temperate  climates,  has  been  considered  as  the  cause  of 
the  frequency  of  calculous  affections  in  Holland,  England,  and 
France,  while  they  are  very  rare  in  more  southern  countries,  in 
which  the  cutaneous  perspiration  seems  to  be  substituted,  in 
great  measure,  to  the  urinary  secretion.  There  is  no  part  of  the 
world  in  which  cases  of  stone  in  the  bladder  are  more  frequent 
than  in  England,  and  especially  in  Holland,  in  which  a cold  and 
damp  atmosphere  is  unfavourable  to  perspiration,  which  is,  at 
any  rate,  but  scanty  in  persons  of  a leucophlegmatic  tempera- 
ment like  that  of  the  Dutch.  In  no  other  country,  could  a litho- 
tomist  (Raw)  have  operated  on  more  than  fifteen  hundred 
patients,  it  is  said,  successfully.  Diabetes,  or  an  immoderate 
discharge  of  urine,  a disease  which  appears  to  depend  on  an  ex- 
cessive relaxation  of  the  renal  tissue,  is  of  frequent  occurrence 
only  in  cold  and  damp  countries,  as  Holland,  England,  and  Scot- 
land; it  is  more  rare  in  France  and  Germany,  and  is  unknown 
in  warm  climates.  This  relaxation  of  the  renal  tissue,  in  diabetes, 
depends  on  the  exhaustion  of  the  urinary  organs  called  into  too 
frequent  action,  as  is  proved  by  the  efficacy  of  tonics  and  astrin- 
gents in  the  treatment  of  that  complaint. 

Cutaneous  affections,  on  the  contrary,  seem  to  belong  to  the 
inhabitants  of  southern  countries.  Lepra  originated  in  Judea, 


OP  DIGESTION. 


156 

the  elephantiasis  rubra  of  Cayenne,  the  framboesia  of  Java,  the 
yaws,  elephantiasis,  herpetic  and  psoric  eruptions,  are  more  fre- 
quent among  the  inhabitants  of  southern  latitudes,  than  among 
those  who  live  under  the  temperate  zones.  In  countries  near  to 
the  equator,  the  surface  of  the  body,  habitually  exposed  to  an  ar- 
dent atmosphere,  is  powerfully  excited;  the  skin  is  irritated,  and 
its  secretion  increased;  perspiration  becomes  so  profuse,  that  it 
weakens,  in  a short  time,  those  who  coming  from  distant  coun- 
tries, are  not  accustomed  to  so  intense  a heat.  The  activity  of 
the  cutaneous  system  exceeds  that  of  the  urinary  system,  whose 
action  decreases  in  proportion,  ^hese  differences  in  the  energy 
of  the  two  systems,  account  readily  for  the  difference  of  their 
diseases:  for,  it  is  a law  of  nature,  that  the  more  an  organ,  or 
system  of  organs,  is  called  into  action,  the  more  it  is  liable  to 
disease,  which  is  but  a derangement  of  its  action. 

Calculous  affections  are  more  frequent  in  children  and  old 
people,  than  in  adults.  In  old  age,  the  proportionate  quantity  of 
the  urine  exceeds  that  of  the  perspiration.  Phosphoric  salts,  the 
base  of  a great  number  of  urinary  calculi,  are  more  abundant  in 
old  men,  as  is  proved  in  them  by  the  ossification  of  the  arteries, 
of  the  ligaments,  of  the  cartilages,  of  the  membranes,  the  solidi- 
hcation  and  the  almost  universal  induration  of  the  different  parts. 
In  children,  the  activity  of  the  urinary  system  is  proportionate 
to  that  of  the  digestive  organs.  Destined  to  throw  out  the  re- 
sidue of  nutrition,  which,  at  that  period,  is  very  active,  the  or- 
gans by  which  the  urine  is  secreted  are  likewise  endowed  with 
considerable  energy.  Lastly,  it  is  observed,  that  the  greatest 
number  of  calculous  patients  received  into  the  hospitals  of  large 
towns,  come  from  low  and  damp  streets  near  to  rivers;  every 
thing,  therefore,  tends  evidently  to  establish,  that  the  frequency 
of  urinary  calculi  depends  on  an  increase  of  activity  in  the  or- 
gans destined  to  the  secretion  and  excretion  of  urine. 


157 


CHAPTER  II. 

OF  ABSORPTION. 

XL.  In  the  history  of  the  phenomena  of  life,  a statement  of 
the  functions  of  the  absorbent  system  ought  immediately  to  foL 
low  that  of  the  functions  of  the  digestive  organs.  The  vessels, 
which  take  up  the  chyle  separated  from  the  food,  by  the  action 
of  the  organs  of  digestion,  form  a considerable  part  of  the  ab- 
sorbent system,  bear  a perfect  resemblance  to  the  other  lympha- 
tics, and  differ  from  them  only  in  their  origin.  When  digestion 
is  not  going  on,  those  vessels  convey  lymph  absorbed  in  the  in- 
testinal canal,  the  inner  part  of  which,  even  when  in  a state  of 
emptiness,  is  always  bedewed  by  an  abundant  quantity  of  serous 
mucus. 

There  exist  in  all  the  parts  of  the  human  body,  in  the  interior,  as 
well  as  on  the  surface  of  our  organs,  vessels  whose  office  it  is  to 
absorb,  and  to  carry  into  the  mass  of  the  blood,  those  substances 
by  which  our  machine  is  maintained  and  kept  in  repair,  as  well 
as  what  comes  off  in  the  continual  destruction  of  our  parts;  for,  it 
must  not  be  forgotten,  that  the  organized  and  living  machine, 
inwardly  acted  upon  by  a double  impulse,  is  perpetually  under- 
going decay  and  renovation. 

XL  I.  Absorption  is  effected  on  substances  introduced  from 
without;  such  is  the  absorption  from  the  skin,  and  the  absorption 
of  the  chyle,  &c.  At  other  times,  absorption  takes  place  in  fluids 
effused  by  arterial  transudation;  such  is  the  serosity  which  mois- 
tens the  serous  membranes,  the  fat,  the  marrow  of  the  bones, 
and  this  absorption,  almost  always,  bears  a proportion  to  transu- 
dation, so  that  the  serosity,  absorbed  as  fast  as  it  is  effused  on 
the  surface  of  the  membranes  which  lie  in  close  contact,  except 
in  cases  of  dropsy,  never  accumulates  so  as  to  separate  those 
membranes.  Finally,  there  is  a kind  of  absorption,  which  may 
be  termed  nutritive  or  molecular,  because  it  exerts  its  influence 
on  molecules,  which,  in  the  process  of  nutrition,  are  separated 
from  the  organs  and  replaced  by  others.  It  is  this  absorption 
which  brings  about  the  decomposition  pf  prgans,  and  to  which 


Of  ABSORPTION. 


158 

John  Hunter  gave  the  name  of  interstitial  absorption.  By  means 
of  it,  the  thymus,  so  voluminous  in  the  foetus,  disappears  entirely 
in  the  adult.  This  absorption  seems  to  be  incessantly  going  on, 
and  to  carry  on  decomposition,  with  a force  that  cannot  be  re- 
sisted. It  explains,  in  a satisfactory  manner,  the  spontaneous 
erosions  of  the  living  solids,  of  which  ulceration^  is  the  conse- 
quence. This  inward  absorption  is  promoted  by  inflammation, 
hence  the  advantage  of  applying  heat  to  indolent  tumours,  and 
of  exciting  a slight  inflammation  in  swollen  glands,  in  order  to 
bring  about  resolution.  It  is  on  that  account,  that  on  swelling 
and  induration  of  the  testicle,  unattended  by  cancer  of  the  part, 
the  operation  for  hydrocele  by  injection,  may  be  safely  employ- 
ed.— Of  this  I had  a convincing  proof,  a few  years  ago:  a gar- 
dener, born  deaf  and  dumb,  had  had  for  some  years  an  hydrocele, 
which  he  was  in  the  habit  of  getting  tapped  every  six  months. 
When  I last  tapped  it,  I found  the  testicle  swollen  and  hard,  and 
three  times  larger  than  in  its  natural  state;  the  patient,  however, 
w’as  free  from  pain.  A considerable  quantity  of  a reddish  serous 
fluid  was  discharged;  at  the  end  of  two  days,  inflammation  of 
the  tunica  vaginalis  came  on,  the  scrotum  became  enlarged  and 
was  covered  with  emollient  poultices.  At  the  end  of  twenty 
days,  the  testicle  was  a good  deal  lessened  in  size  and  adhered 
to  the  inside  of  the  tunica  vaginalis:  the  cure  was  considered  ra- 
dical and  proved  such;  for,  though  it  is  now  ten  years  since  the 
operation  was  performed,  the  water  has  not  collected  and  the 
patient  continues  in  the  laborious  employments  of  his  business. 
I frequently  meet  him,  and  he  never  fails,  by  inarticulate  sounds 
and  signs  of  satisfaction,  to  express  to  me  his  gratitude. 

The  process  of  absorption,  is  very  active  in  children,  in 
women,  during  sleep,  in  the  morning  when  the  body  is  refreshed 
by  the  night’s  rest.  Is  it  a staje  of  weakness  favourable  or  unfa- 
vourable to  that  process?  It  is  well  known,  that  there  are  robust 
men  who  have  intercourse  with  women  infected  with  the  vene- 
real virus,  and  who  escape  the  contagion,  unless  they  expose 
themselves  to  it  when  debilitated  by  excesses.  A mind  free  of 
fear  and  anxiety,  has  ever  been  considered  in  the  Eastern  coun- 
tries, a safe  guard  against  the  plague.  A dog,  csteris  paribus,  is 


Nosographie  Chirui;icale,  tome  I.  art.  Ulceres  Atoniques, 


OP  ABSORPTION, 


159 

in  much  less  danger  from  the  bite  of  a viper,  when  suddenly- 
bitten,  than  when  he  has  been  some  time  gazing  at  the  reptile, 
and  more  or  less  terrified  by  the  sight.  But  in  all  these  cases, 
does  debility  favour  the  introduction  of  the  contagious  matter, 
by  increasing  the  force  of  absorption;  or  is  it  not  more  probable, 
that  by  affecting  the  nervous  system,  it  renders  it  more  suscep- 
tible of  deleterious  impressions?* 

XLII.  Absorption  is  much  less  active,  on  the  external  sur- 
face of  the  body,  than  on  the  surface  of  its  internal  cavities,  and 
in  the  very  substance  of  our  organs.  Cutaneous  absorption,  under 
certain  circumstances,  has  even  so  little  activity,  as  to  have  led 
some  physiologists  to  doubt  its  existence.  The  absorbing  orifices 
of  vessels  which  arise  on  the  surface  of  the  body,  are  covered 
by  the  epidermis.  This  covering,  which  is  insensible,  and,  as  it 
were,  inorganic,  forms  a sort  of  separation,  between  the  external 
and  internal  part  of  our  being,  and  opposes,  or  renders  more 
difficult,  the  absorption  of  substances  in  immediate  contact  with 
our  body;  and  if  it  be  considered,  that  we  are  frequently  im- 
mersed in  the  midst  of  gases  and  other  substances,  to  a certain 
degree  deleterious,  it  will  be  understood,  how  essential  it  was, 
that  the  absorbing  surface  of  the  skin  should  not  be  entirely 
exposed,  and  that  cutaneous  absorption  should  not  be  easily 
carried  on. 

The  increased  weight  of  the  body,  after  exercise  in  wet 
weather;  the  abundant  secretion  of  urine,  after  remaining  long  in 
the  bath;  the  manifest  enlargement  of  the  glands  of  the  groin, 
after  keeping  the  feet  immersed,  for  a considerable  time,  in 
water,  an  experiment  often  performed  by  Mascagni  on  himself; 
the  effects  of  mercurial  frictions,  &c.  show,  however,  in  an  un- 
questionable manner,  that  absorption  takes  place  through  the 
skin,  with  more  or  less  rapidity,  according  to  circumstances.  It 
must  be  taken  into  account,  that  the  means  which  promote  cuta- 
neous absorption,  operate,  at  least  as  much,  by  altering  the  struc- 
ture of  the  epidermis,  as  by  increasing  the  action  of  the  ab- 
sorbing orifice.  In  this  manner,  the  bath  appears  to  operate,  by 
softening  the  texture  of  the  epidermis;  and  frictions,  by  dis- 
placing and  raising  its  scales. 


♦The  latter  is  undoubtedly  the  explanation.—£D. 


OF  ABSORPTION. 


16® 

It  is  by  means  of  frictions,  that  we  succeed  in  introducing  into 
the  lymphatic  system,  medicines  possessing  purgative,  febrifuge, 
sedative,  or  diuretic  qualities,  combined  with  the  gastric  juice, 
or  diluted  in  any  other  liquids;  for,  as  has  been  shewn  by  the  ex- 
periments performed  at  the  Salpetriere,  by  M.  M.  Dumeril 
and  Alibert,  in  the  name  of  the  Philomatic  Society,  the  mixture 
with  saliva  or  gastric  juice,  of  the  medicines  which  are  to  be  ad- 
ministered by  friction,  is  not  necessary  to  insure  their  absorp- 
tion. Extract  of  opium  has  soothed  pain,  bark  has  checked  fits 
of  intermittent  fever,  rhubarb  has  procured  alvine  evacuations; 
squills  have  stimulated  powerfully  the  action  of  the  urinary  or- 
gans, nor  has  the  previous  mixture,  with  gastric  juice,  of  these 
substances  reduced  into  powder,  seemed  to  increase  or  diminish 
their  efiicacy. 

Absorption  takes  place  quickly  and  readily,  wherever  the  epi- 
dermis is  thin,  habitually  moist,  and  the  skin  delicate,  so  as  to 
leave  almost  bear  of  covering,  the  subjacent  parts,  as  on  the  lips, 
in  the  inside  of  the  mouth,  on  the  surface  of  the  glands,  &c.  The 
complete  removal  of  the  epidermis,  favours  absorption  from  all 
parts  of  the  skin  which  it  covered.  Hence  the  least  scratch  on 
the  fingers  of  an  accoucheur  touching  women  infected  with  the 
veneral  virus,  exposed  him  to  this  peculiar  infection,  which,  in 
such  cases,  is  the  more  to  be  dreaded,  from  the  admission  of 
the  virus  by  an  unusual  course.  The  inoculation  of  variolous 
and  vaccine  matter,  equally  furnishes  proofs  of  the  obstacle 
which  the  epidermis  presents  to  cutaneous  absorption,  and  of 
the  facility  with  which  that  function  takes  place,  from  surfaces 
denuded  of  that  covering.  Absorption  goes  on,  likewise,  with 
great  activity,  from  the  surfaces  of  internal  parts,  but  it  no 
where  is  so  considerable  as  in  the  intestinal  canal,  and  it  would 
perhaps  be  the  most  favourable  part  for  introducing  medicinal 
substances  into  the  animal  economy,  if  when  swallowed,  they 
did  not  undergo  changes,  by  mixing  with  the  gastric  juices,  or 
with  the  intestinal  fluids  and  faecal  substances,  when  injected  by 
the  rectum.  From  the  evacuation  by  urine  of  clysters  of  warm 
water,  soon  after  they  have  been  administered,  it  is  to  be  pre- 
sumed, that  the  great  intestines  absorb  almost  as  powerfully  as 
the  rest  of  the  digestive  canal.  A pint  of  warm  water  injected 
into  the  abdomen  of  a large  dog  or  sheep,  is  often  absorbed  in 


OF  ABSORPTIOK 


161 


less  than  an  hour,  and  the  effusions  which  take  place  in  those 
cavities,  would  possibly  not  require  an  operation  to  let  them  out, 
if  such  fluids  were  not  subject  to  coagulation,  and  if  the  absorb- 
ing surfaces  were  not  diseased.^ 

* It  is  now  thirteen  years  since  the  subject  of  cnticular  absorption  first  en- 
gaged the  attention  of  the  medical  men  of  this  city,  during  which  time,  it  has 
been  prosecuted  with  an  ardour  and  success  highly  honourable  to  those  con- 
cerned in  the  inquiry.  As  early  as  the  year  1800,  it  was  shown,  or  at  least  ren- 
dered highly  probable  by  Dr.  Rousseau,  that  the  pulmonary  organs,  and  not 
the  skin,  constitute  the  avenue  through  which  certain  substances  enter  the 
system.  By  cutting  off  all  communication  with  the  lungs,  which  he  easily 
effected  by  breathing  through  a tube  protruded  into  the  external  atmosphere, 
he  found  that  though  the  surface  of  his  body  were  bathed  with  the  juice  of 
garlic  or  the  spirits  of  turpentine,  none  of  the  qualities  of  these  fluids  could 
be  detected,  either  in  the  urine,  or  serum  of  the  blood.  Conducted  nearly  on 
the  same  principle,  but  with  a greater  diversity  of  substances,  experiments  ex- 
ceedingly well  devised  and  ably  executed,  have  since  been  made,  by  persons  of 
opposite  prepossessions,  to  an  almost  incredible  extent.  Contradictory  as  many 
of  these  are,  a candid  examination  of  the  whole  will  still  lead  to  a pretty  satis- 
factory conviction,  that  absorption  from  the  surface  of  the  human  body  does 
not  exist  as  a natural  and  ordinary  function. 

Borne  down  by  the  weight  of  evidence  against  them,  most  of  the  advocates 
of  the  ancient  hypothesis  were  indeed  prepared  to  abandon  it,  as  no  longer 
tenable,  when  about  two  years  ago  an  experiment  made  by  Dr.  Massy  again 
revived  their  faith  in  cuticular  absorption.  This  experimentalist  very  clearly 
proved  that  if  the  body  be  immersed  in  a decoction  of  madder,  the  colouring 
matter  of  this  substance  will  be  taken  in,  and  may  be  displayed  in  the  urine, 
by  using  any  one  of  the  alkalies  as  a test. 

Determined,  if  possible,  to  put  this  long  agitated  question  to  rest.  Dr. 
Rousseau,  assisted  by  his  friend  Dr.  Samuel  B.  Smith,  has  subsequently  per- 
formed a series  of  experiments,  many  of  which  we  witnessed,  with  every 
variety  of  substance,  mild  and  acrid,  volatile  and  fixed,  nutritive,  medicinal, 
and  poisonous. 

The  result  of  these  extensive  researches  is: 

1.  That  of  all  the  substances  employed,  madder  and  rhubarb  are  those  only 
W'hich  affect  the  urine.  The  latter,  of  the  two,  the  more  readily  enters  the 
system.  Neither  of  these  substances  can  be  traced  in  any  other  of  the  secre- 
tions, or  excretions,  or  in  the  serum  of  the  blood. 

2.  That  the  power  of  absorption  is  limited  to  a very  small  portion  of  the 
surface  of  the  body.  The  only  parts  indeed  which  seem  to  possess  it,  are  the 
spaces  between  the  middle  of  the  thigh  and  hip,  and  between  the  middle  of 
the  arm  and  shoulder.  Topical  bathing  with  a decoction  of  rhubarb  or  madder, 
or  poultices  of  these  substances  applied  to  the  back,  or  abdomen,  or  sides,  or 
shoulders,  produced  no  change  in  the  urine,  &c.  Equally  ineffectual  was  the 
immersion  of  the  feet  and  hands  in  a bath  of  the  same  materials.  After  being 
kept  in  it  several  hours,  not  the  slightest  proof  of  absorption  was  afforded. 

Such  is  the  state  in  which  this  interesting  subject  is  at  present  left.  Though, 

X 


OF  ABSORPTION. 


162 

Besides  absorption  from  surfaces,  there  exists,  as  we  hare 
already  stated,  another  which  takes  place  in  the  living  solid,  and 
in  the  internal  substance  of  the  organs.  It  is  by  this  kind  of  ab- 
sorption that  the  nutritive  decomposition  is  effected;  by  means 
of  it,  the  living  matter  is  incessantly  renovated.  Its  vitiated  ac- 
tion accounts  for  the  spontaneous  formation  of  ulcers,  the  disap- 
pearing of  the  thymus,  the  atrophy  of  parts  in  which  nutrition 
is  carried  on,  in  a sluggish  manner;  the  resolution  of  certain 
tumours,  and  many  other  phenomena,  are  dependent  on  the 
same  cause.  I do  not  think,  however,  that  it  is  possible  to  admit 
the  explanation  of  the  sensation  of  hunger,  adopted  by  Profes- 
sor Dumas,  who  believes  that  it  depends  on  the  action  of  the 
absorbing  orifices  directed  against  the  organized  substance  of 
the  stomach,  in  the  absence  of  aliment  on  which  to  act.  The 
sensation  of  hunger  is  felt  only  in  the  stomacli,  although  its 
effects  extend  to  all  parts  of  the  body;  it  begins  in  a circum- 
scribed spot,  its  seat  is  limited,  yet  absorption  takes  place  every 
where,  so  that  if  the  hypothesis  in  question  had  any  foundation, 
the  sensation  of  hunger  ought  to  be  felt  at  the  heel,  as  well  as 
at  the  pit  of  the  stomach.* 

perhaps,  not  absolutely  decided,  enough  surely  has  been  done  to  demonstrate 
that  culicular  absorption  rarely  happens,  and  that  whenever  it  does,  it  can  not 
be  deemed  the  effort  of  a natural  function.  Covered,  as  is  the  whole  surface  of 
the  body  by  the  impervious  cuticle,  it  is  manifest  to  us  that  absorption  can  only 
take  place  in  one  of  two  ways,  either  by  forcing  the  substance  under  the 
scales  of  the  epidermis,  as  in  the  instance  of  the  application  of  frictions,  or  by 
long  continued  bathing,  the  cuticle  becomes  so  changed  in  its  organization,  as  to 
admit  of  transudation,  or  the  insinuation  of  the  fluid  under  its  squamous  struc- 
ture, so  as  to  come  in  contact  with  the  mouths  of  the  lymphatics  situated 
within. 

At  all  events,  whatever  difference  of  opinion  may  be  entertained  as  to  the 
degree  of  conclusiveness  of  the  experiments  to  which  I have  alluded,  it  can 
hardly  be  thought  necessary  to  resort  to  cuticular  absorption,  to  explain  the 
facts  enumerated  by  our  author  as  proofs  of  the  existence  of  the  function. 
These,  and,  perhaps,  all  other  phenomena,  hitherto  referred  to  the  agency  of 
absorption  by  the  skin,  may  be  more  rationally  accounted  for  on  the  principle 
of  pulmonary  absorption,  and  the  law  of  sympathy. — Ed. 

* Both  hunger  and  thirst  seem  to  be  sensations,  excited  by  the  stomach’s 
sympathising  with  the  general  exhaustion  of  the  system,  and  are  the  means 
employed  by  nature  to  admonish  us  of  the  necessity  of  repairing  the  wastes 
which  it  sustains  from  abstinence.  An  office  so  important  to  our  well  being,  and 
even  existence,  is  not  left  to  reason,  which  might  often  err,  but,  is  put  under 
the  care  of  an  instinct,  far  more  certain  in  its  operation.  Besides  these  two  sen- 


OF  ABSORPTION. 


163 

The  radicles  from  which  the  lymphatics  arise,  have  orifi.es 
so  very  minute,  that  they  are  imperceptible  to  the  naked  eye;  a 
tolerably  accurate  notion  may  be  formed  of  them,  by  comparing 
them  to  the  puncta  lachrymalig,  which  are  larger  and  more 
easily  discovered.  Each  orifice  endowed  with  sensibility,  and 
with  a peculiar  power  of  contraction,  dilates  or  contracts,  ab- 
sorbs or  rejects,  according  as  it  is  affected  by  the  substances 
which  are  applied  to  it.  The  variations  of  the  absorbing  power, 
according  to  the  age,  the  sex,  the  constitution,  and  different  pe- 
riods of  the  day,  show  that  it  cannot  be  compared,  as  several 
physiologists  have  done,  to  that  principle  which  makes  fluids 
ascend,  contrary  to  the  laws  of  gravitation,  in  capillary  tubes. 
If  absorption  were  a process  merely  mechanical,  it  would  in  no 
case  be  accelerated  or  retarded,  and  would  proceed  with  a re- 
gularity never  abserved  in  the  vital  functions.  The  mouth  of 
every  lymphatic,  when  about  to  absorb,  erects  itself,  draws 
towards  itself,  and  raises  the  surrounding  membranous  parts, 
and  thus  forms  a small  tubercle  similar  to  the  puncta  lachry- 
inalia.  These  little  bulgings  deceived  Leiberkuhn,  and  led  him 
to  think,  that  the  absorbents  of  the  intestines  originated  from 
small  ampullulse,  or  vesicular  enlargments,  which,  as  so  many 
exhausted  receivers,  pumped  up  the  fluid  extracted  from  the 
food.  This  physiologist  may,  further,  have  been  led  into  error, 
by  the  nervous  papillae  of  the  inner  membrane  of  the  canal,  swol- 
len by  the  determination  of  blood  attending  irritation,  the  natu- 
ral consequence  of  the  friction  of  the  alimentary  substances. 
The  inhaling  faculty  belongs  not  only  to  the  orifices  at  the  ex- 
tremity of  each  radicle,  but  likewise  to  the  lateral  pores,  which 
are  infinitely  numerous  in  the  parietes  of  the  vessels.* 

sations  the  stomach  has  others  equally  specific,  as  satiety,  longing,  loathing, 
sickness,  &c.  &c. — Ed. 

* As  to  the  precise  manner  in  which  absorption  is  effected,  physiologists  are 
not  agreed.  By  some  it  is  contended  that  it  is  entirely  the  result  of  capillary 
attraction.  To  the  exercise  of  this  species  of  affinity,  three  circumstances  seem 
•nly  to  be  demanded: 

1.  The  tube  must  not  exceed  a certain  size. 

2.  It  must  be  of  an  equal  caliber  throughout. 

3.  One  of  its  extremities  must  be  immersed  in  a fluid. 

Notwithstanding  what  has  been  urged  to  the  contrary,  capillary  attraction 

unquestionably  is  influenced  neither  by  the  flexibility  of  the  tube,  nor  its  posi- 
^on.  It  is  now  perfectly  well  ascertained,  that  the  operation  goes  on  whether 


164 


OF  ABSORPTION. 


XLIII.  After  arising  on  the  surface,  and  in  the  interior  of 
the  body,  by  radicles  in  close  contact,  the  lymphatics  creep  and 
coil  themselves,  describe  numerous  curves,  unite,  then  divide, 
and  presently  unite  again,  and  from  these  numerous  inoscula- 
tions, there  results  a net-work,  with  close  meshes,  forming, 
with  that  of  the  blood  vessels,  the  texture  of  the  cellular  tissue 
and  of  the  membranes. 

Each  lamina  of  cellular  tissue  is,  in  the  opinion  of  Mascagni, 
nothing  but  a mesh-work  of  lymphatics;  the  texture  of  the  mem- 
branous and  transparent  tissues,  as  the  pleura  and  the  perito- 
neum, resembles  that  of  the  laminae  of  the  cellular  tissue;  in 
fine,  the  same  vessels  form  the  basis  of  the  mucous  membranes 

the  tube  be  soft  or  hard,  or  whether  it  be  placed  vertically,  horizontally,  or 
obliquely. 

These  facts  being  admitted,  and  also,  that  the  lymphatic  vessels  are  within 
the  dimensions  necessary  to  capillary  attraction,  which  they  undoubtedly  are, 
the  hypothesis  referring  absorption  to  this  principle  does  not,  on  first  view, 
strike  us  as  altogether  unreasonable.  When  examined,  however,  more  clear- 
ly, it  will  be  found  liable  to  all  the  embarrassments  enumerated  in  the  test, 
and  to  others  of  not  less  weight. 

Two  additional  objections  at  once  occur  to  us: 

1.  Did  the  absorbents  act  mechanically,  as  is  alleged,  they'  would  take  up 
indiscriminately  all  fluids  presented  to  their  moutlis,  instead  of  which,  they 
exercise  a degree  of  selection  amounting  almost  to  fastidiousness. 

2.  The  absorbents  have  not  that  mechanism  which  capillary  attraction  re- 
quires. They  frequently  swell  or  bulge  out  in  their  course,  and  become  of 
irregular  capacities.  Even  at  their  or.fices  they  assume  the  figure  of  the  fun- 
nel, commencing  with  an  exceedingly  minute  opening,  which  suddenly  ex- 
pands. Aware  of  the  unfavourableness  of  this  structure  to  the  progression  of 
fluids,  it  has  been  maintained  by  some  other  of  the  advocates  of  capillary  at- 
traction, that  the  fluid  is  simply  imbibed  by  the  power  of  this  principle,  and 
afterwards  propelled  by  the  united  force  of  muscular  pressure,  and  the  action 
of  the  contiguous  arteries. 

We  do  not  think  the  hypothesis  at  all  improved  by  this  modification  of  it. 
We  believe,  that  in  absorption  there  is  no  capillary  influence,  or,  indeed,  any 
sort  of  extrinsic  agency  employed.  It  seems  to  us  to  be  owing  altogetlier  to 
the  inherent  contractile  power  of  the  vessel,  and  bears  no  very  remote  analogy 
to  the  peristaltic  action  of  the  intestines.  We  will,  however,  in  a few  words, 
explain  our  meaning  more  distinctly. 

When  chyle,  or  any  appropriate  fluid,  is  applied  to  the  mouth  of  an  absor- 
bent, it  is  excited  by  tbe  stimulus  of  the  fluid  to  an  erection  of  its  orifice,  in 
consequence  of  which,  the  latter  is  rendered  pervious.  The  fluid  being  now 
introduced,  the  vessel  contracts,  and  propels  its  contents  in  succession  along 
its  course  to  the  ultimate  destination.— Ed. 


0F  ABSORPTION. 


165 

which  line  the  internal  parts  of  the  alimentary  canal,  of  the 
trachea  and  urethra.  The  Italian  anatomist  succeeded  in  filling, 
with  quicksilver,  all  the  tissues  which  he  considered  as  lymphatic; 
but  Ruysch,  in  his  admirable  injections,  reduced  all  the  mem- 
branes, and  the  laminae  of  the  adipose  tissue,  into  a net-work 
purely  arterial,  of  which  the  meshes  were  so  very  closely  united, 
as  to  leave  spaces  that  could  scarcely  be  perceived  by  the  mi- 
croscope; and  from  his  preparations  he  inferred,  that  arterial 
capillary  vessels,  singularly  divided  and  convoluted,  form  the 
basis  of  cellular  and  membranous  tissues.  To  satisfy  oneself 
that  neither  the  pleura  nor  the  peritoneum  are  formed  as  Mas- 
cagni or  Ruysch  imagined,  one  need  only  consider,  that  arterial 
exhalation  and  lymphatic  absorption  take  place  from  the  whole 
extent  of  the  internal  surfaces,  and  that  these  two  functions 
prove  the  existence  of  both  arteries  and  absorbents,  in  those 
membranes  and  in  the  cellular  tissue.  The  prejudices  of  those 
two  anatomists,  so  celebrated,  the  one  by  his  study  of  the  absor- 
bents, and  the  other  by  his  beautiful  injections  of  the  most  mi- 
nute arteries,  are  to  be  attributed  to  the  importance  which  we 
are  pleased  to  assign  to  the  objects  which  particularly  engage 
our  attention,  and  likewise  to  the  distention  of  the  minute  ves- 
sels by  the  injection;  these  being  distended  beyond  their  natural 
state,  compress  and  conceal  the  neighbouring  parts. 

The  lymphatics,  after  emerging  from  among  the  cellular  sub- 
stance, unite  into  trunks  sufficiently  large  to  be  distinguished 
from  the  laminse  of  that  tissue.  These  trunks  proceed  towards 
certain  parts  of  the  body,  there  they  become  united  to  other 
trunks,  follow  a parallel  course  and  frequently  communicate 
together.  The  lymphatics  are  not  single  in  their  course,  as  the 
arteries  and  veins;  they  collect  together,  form  fasciculi  of  diffe- 
rent sizes,  some  of  which  are  deep  seated  and  accompany  the 
blood  vessels,  while  others  of  them  are  more  superficial,  corres- 
ponding to  the  subcutaneous  veins  of  the  limbs,  and,  like  them, 
lying  between  the  skin  and  the  aponeuroses,  and  in  greatest 
number,  on  the  inner  side  of  the  limbs,  in  which  they  are  best 
protected  against  external  injuries.  The  lymphatics  of  the  pa- 
rietes  of  the  great  cavities,  those  of  the  viscera  which  these 
cavities  contain,  are  likewise  in  two  layers,  the  one  superficial, 
the  other  deep  seated. 


OF  ABSORPTION, 


166 

The  absorbents  differ,  likewise,  from  the  blood  vessels,  in 
their  singularly  tortuous  course,  their  frequent  communications, 
and  especially  in  their  unequal  size  in  different  parts  of  their 
extent.  An  absorbent  of  very  small  dimensions,  frequently  en- 
larges, so  as  to  equal  in  size  the  thoracic  duct,  then  contracts, 
and  again  bulges  out,  though  in  the  length  of  the  vessel  in  which 
these  differences  of  size  may  have  been  noticed,  it  may  have  re- 
ceived no  collateral  branches.  The  lymphatics,  when  completely 
filled  with  quicksilver,  appear  to  cover  the  whole  surface  of  our 
organs:  and  the  whole  body  seems  enveloped  in  a net-work  of 
close  and  small  meshes.  The  metastasis  of  humours,  from  one 
part  of  the  body  to  another  at  a distance,  is  easily  understood 
by  any  one  who  has  seen  those  numerous  inosculations  render- 
ed manifest  by  injection.  Metastasis  ceases  to  be  an  inexplica- 
ble phenomenon;  one  has  no  diflSculty  in  conceiving  how,  by 
means  of  the  lymphatics,  all  the  parts  of  the  body  communicate 
freely;  how,  fluids  absorbed  by  those  vessels  in  one  part,  maybe 
conveyed  into  another,  and  prevade  the  whole  body,  without 
following  the  circuitous  route  of  the  circulation,  and  that  it  is, 
therefore,  not  altogether  impossible,  however  improbable,  that 
fluids  taken  into  the  stomach,  may  be  conveyed  directly  from 
the  stomach  to  the  bladder,  and  that  in  the  same  manner,  the 
milk  of  the  intestinal  canal  may  find  its  way  into  the  breasts; 
and  that  pus  may  be  removed  from  the  place  in  which  it  is  col- 
lected, and  be  conveyed  to  the  place  to  which  .irritation  calls  it 
forth.  All  that  Bordeu  has  said  to  the  oscillations  and  currents 
of  humours,  through  the  cellular  texture,  in  his  “ Recherches 
sur  le  Tissu  muqueux''  may  be  equally  explained  by  the  anasto- 
mosis of  the  lymphatics. 

A young  man  whom  I had  ordered  to  rub  in  mercury  along 
the  inner  part  of  his  left  leg  and  thigh,  for  the  cure  of  a pretty 
large  bubo,  was  affected,  on  the  third  day,  with  salivation, 
though  he  used  only  half  a dram  of  ointment  at  each  friction. 
The  salivary  glands  of  the  left  side  were  alone  swollen,  the  left 
side  of  the  tongue  was  covered  with  aphthae,  and  the  right  side 
of  the  body  remained  unaffected  by  the  mercurial  action;  a clear 
proof,  that  the  mercury  had  been  carried  to  the  mouth,  along  the 
left  side  of  the  body,  without  entering  into  the  course  of  the  cir- 
culation, and  perhaps,  without  passing  through  any  of  the  con- 


OF  ABSORPTION. 


167 

globate  glands;  for,  that  of  the  left  groin,  which  alone  was 
swollen,  did  not  sensibly  diminish  in  size.  Salivation  may,  there- 
fore, take  place  in  the  cure  of  venereal  disease,  though  none  of 
the  mercury  enter  the  circulation,  which  warrants  the  opinion, 
that  the  action  of  syphilis,  as  well  as  of  the  remedies  which  are 
administered  for  its  removal,  operates  chiefly  on  the  lymphatic 
system. 

XL IV.  If  the  fluids  absorbed  by  these  vessels  can,  in  conse- 
quence of  their  numerous  inosculations,  pervade  all  parts  of  the 
body,  without  mixing  with  the  blood,  not  a drop  can  enter  the 
course  of  the  circulation,  without  having  previously  passed 
through  the  glandular  bodies  that  lie  in  the  course  of  the  lym- 
phatics; dispersed  like  those  vessels  in  all  parts  of  the  body, 
seldom  insulated,  but  in  clusters  in  the  hollows  of  the  ham,  the 
arm-pit,  in  the  bends  of  the  groin  and  elbow,  along  the  iliac  ves- 
sels, the  aorta  and  the  blood  vessels  of  the  neck,  around  the 
base  of  the  jaw  and  of  the  occiput,  behind  the  sternum,  along  the 
internal  mammary  vessels,  lastly,  within  the  mesentery,  in  which 
their  number  and  size  bear  a proportion  to  the  quantity  of  ab- 
sorbents which  pass  through  them.  These  reddish  glands,*  vary- 
ing in  size  of  an  oval  or  globular  form,  have  two  extremities, 
the  one  at  which  the  lymphatics  enter,  they  are  then  called 

aff'erentia^'  and  the  other  extremity  turned  towards  the  tho- 
racic duct,  which  sends  out  vessels,  fewer  in  number,  but  of  a 
larger  size,  and  called  “ efferentid'  from  their  use. 

The  lymphatics,  on  reaching  the  glands,  divide,  unite  again 
and  inosculate,  they  likewise  bend  back  on  themselves,  and  thus 
form  the  tissue  of  the  conglobate  glands,  which  are  merely  clus- 
ters of  coiled  vessels,  united  by  cellular  tissue,  in  which  blood 
vessels  are  distributed,  so  as  to  occasion  their  reddish  colour. 
The  coats  of  the  lymphatics  are  thinner  in  the  glands  than  else- 
where; and  their  dilatations,  their  divisions,  and  their  anasto- 
moses are  likewise  more  frequent,  while  they  are  in  the  glandu- 

• It  is  with  a view  of  conforming  to  the  language  in  common  use,  that  I give 
the  name  of  gland  to  those  coils  of  lymphatic  vessels,  which  are  totally  diffe- 
rent from  the  real  conglomerate  or  secretory  glands.  It  might  be  better,  per- 
haps,  to  call  them  ganglions,  as  has  been  done  by  my  learned  and  respected  col- 
league Chaussier,  though  that  name  is  objectionable,  from  its  association  in 
the  mind  with  the  nervous  ganglions,  whose  structure  is  not  at  all  similar  t* 
that  of  the  lymphatic  ganglions. 


OF  ABSORPTION*. 


168 

lar  tissue.  All  the  lymphatic  vessels,  whose  course  lies  in  the 
direction  of  a gland,  do  not  enter  its  substance;  several  pass  by 
the  gland  and  embrace  it,  forming  around  it  a sort  of  plexus,  of 
which  the  ramifications  are  directed  towards  other  glands,  more 
in  the  vicinity  of  the  thoracic  duct.  The  lymphatic  glands 
form  so  essential  a part  of  the  absorbent  system,  they  produce 
on  the  lymph  such  indispensable  changes,  that  no  lymphatic 
vessel  enters  the  thoracic  duct,  without  having  previously  pass- 
ed through  these  glands.  It  even  frequently  happens,  that  the 
same  vessel  passes  through  several  glands,  before  opening  into 
that  common  centre  of  the  lymphatic  system.  Thus,  the  vessels 
which  absorb  the  chyle  of  the  intestinal  tube,  pass  several  times 
through  the  glands  of  the  mesentery. — The  lymphatics  of  the 
liver,  situated  very  near  to  the  receptaculum  of  Pecquet,  have 
been  thought,  by  some  anatomists,  not  to  follow  that  general 
rule;  but  there  are  uniformly  found,  in  the  course  of  these  ves- 
sels, glands  which  they  enter.  As,  however,  the  glands  are  few 
in  number,  the  lymph  conveyed  from  the  liver  is  only  once  sub- 
jected to  the  action  of  the  glands;  and  this  circumstance  appears 
to  me  to  explain,  in  a satisfactory  manner,  the  transmission  of 
the  colouring  matter  of  the  bile,  which,  in  jaundice,  manifestly 
discolours  the  blood,  in  which  M.  Deyeux  found  it  by  chemical 
analysis. 

XLV.  The  parietes  of  the  lymphatic  vessels  are  formed  of 
two  coats,  both  very  thin  and  transparent,  yet  very  strong,  since 
they  support  the  weight  of  a column  of  mercury,  which  would 
rupture  the  coats  of  arteries  of  the  same  caliber.  The  internal 
coat,  which  is  the  thinner  of  the  two,  forms  valvular  folds,  ar- 
ranged in  pairs,  like  the  valves  of  the  veins,  and  like  them  pre- 
venting a retrograde  circulation. — Although  these  coats  are  very 
strong,  and  likewise  very  elastic  and  contractile,  as  they  may  be 
seen  to  contract,  and  to  expel  the  lymph  with  great  impetus,when 
the  abdomen  of  a living  animal*  is  laid  open,  yet  the  course  of 

* In  some  cases,  the  activity  of  the  absorbents  appears  increased,  in  a singu- 
lar degree.  Thus,  jaundice  has  been  known  to  be  the  immediate  consequence 
of  a wound  of  the  liver;  and  on  other  occasions,  a metastasis  of  humours  has 
taken  place,  with  the  utmost  rapidity.  I suspect,  that,  in  such  cases,  the  sub- 
stance that  has  been  absorbed,  circulates  by  means  of  tlie  anastomoses,  and  per- 
vades the  lymphatics  vrith  which  the  whole  body  is  covered,  but  without  pass- 
ing through  the  glands,  which  would  slacken  its  course,  and,  to  a certain  de- 
gree, alter  its  nature. 


OF  ABSORPTION. 


169 

the  Ivmph  is  far  from  being  as  rapid  as  that  of  the  blood;  it  even 
frequently  appears  affected  with  irregular  oscillations,  such  as 
are  to  be  met  with  in  the  circulation  of  the  blood  through  the 
capillary  arteries.  The  numerous  dilatations,  curvatures  and 
anastomoses  of  the  absorbents  must,  in  a considerable  degree, 
impede  the  rapid  progress  of  the  lymph,  but  the  circulation 
must  be  retarded  chiefly  in  the  glands,  as  there  the  vessels  are 
most  convoluted,  dilated,  and  form  the  greatest  number  of  anas- 
tomoses, and  are  most  subdivided.  Besides,  the  parietes  of  the 
absorbents  are  thinnest  in  their  passage  through  the  glands,  for 
these  may  be  ruptured  by  the  weight  of  a column  of  mercury 
which  the  vessels  themselves  are  able  to  support.  And  the  ac- 
tion of  these  vessels,  naturally  weaker  in  that  situation,  is  still 
farther  diminished  by  the  close  cellular  adhesion  which  unites 
together  the  vessels  whose  union  forms  the  glandular  bodies. 

It  was  necessary  that  the  course  of  the  lymph  should  be  slack- 
ened in  its  passage  through  the  glands,  in  order  that  it  might  un- 
dergo all  the  changes  which  those  organs  are  to  produce  upon  it. 
Although  we  do  not  know  precisely  what  those  changes  are, 
their  object  appears  to  consist  in  a more  perfect  union  and  com- 
bination of  its  elements,  and  in  bestowing  on  it  a certain  degree 
of  animalization,  as  is  seen,  by  the  greater  tendency  to  coagula- 
tion of  the  fluid  taken  from  the  vasa  efferentia.  Another  object 
of  the  passage  of  the  lymph  through  the  glands,  appears  to  be 
to  deprive  it  of  its  heterogeneous  particles,  or  at  least  to  alter 
their  nature,  so  that  they  may  not  become  injurious,  when  they 
get  into  the  mass  of  the  fluids.]  The  yellow  colour  of  the  glands 
through  which  the  absorbents  of  the  liver  pass,  the  dark  colour 
of  the  bronchial  glands,  the  red  colour  of  the  mesenteric  glands, 
in  animals  which  have  been  fed  on  madder  or  beet-root,  the 
whiteness  of  the  same  glands,  while  the  chyle  is  passing  through 
them,  are  circumstances  which  show,  that  the  glands  separate,  or 
tend  to  separate,  the  colouring  matter  of  the  lymph,  and  that  if 
they  do  not  effectually  prevent  its  transmission  into  the  blood,  it 
is  because  certain  colours,  as  indigo  and  madder,  have  too  much 
tenacity,  while  other  substances,  as  the  bile,  do  not  pass  through 
a sufficient  number  of  glands,  to  lose  their  colour  entirely.  The 
blood  vessels,  which  are  very  numerous  in  the  tissue  of  the  con- 
globate glands,  pour  into  the  lymphatics  a serous  fluid  which  di- 

Y 


OF  ABSORPTION, 


170 

lutes  the  lymph,  increases  its  quantity,  and  at  the  same  time, 
animalizes  it.  The  number  of  the  lymphatic  glands  is  very  great; 
many  are  so  small  as  to  escape  the  eye,  but  become  enlarged  and 
visible,  in  certain  cases  of  disease.  I have  daily  opportunities  of 
observing  in  scrophiilous  patients,  swollen  glands,  in  situations 
in  which  anatomists  have  not  pointed  out  any.  The  absorbent 
glands  are,  at  no  time,  so  large  or  numerous  as  in  infancy.  They 
very  frequently  disappear  in  old  people,  and  it  is  difficult  to  say, 
whether  they  have  been  totally  destroyed,  or  whether  they  are 
merely  exceedingly  reduced  in  bulk. 

XL VI.  The  frequent  congestions  of  the  conglobate  glands, 
depend  on  the  stagnation  of  the  lymphatic  fluid  in  their  sub- 
stance, and  on  the  comparative  weakness  of  the  sides  of  the  ves- 
sels in  these  parts.  The  influence  of  debilitating  causes  on  the 
lymphatic  system,  acts  most  powerfully  on  the  glands,  which 
are  the  weakest  part  of  that  system.  In  such  cases,  the  vessels 
which  enter  into  the  composition  of  the  glands,  act  feebly,  or 
cease  to  act  altogether;  the  fluids,  of  which  there  is  a continual 
accession,  accumulate;  the  most  liquid  part  alone  penetrates 
through  the  glandular  organ,  the  grosser  particles  remain,  the 
humour  thickens,  hardens,  and  forms  congestions  of  various 
kinds.  If  there  is  a tendency  to  cancer,  such  tumours,  at  first 
indolent,  become  painful,  the  indurated  matter  being,  in  a man- 
ner, out  of  the  influence  of  the  vital  power,  since  its  vessels  are 
in  a state  of  complete  atony,  undergoes  a sort  of  putrid  fermen- 
tation, the  consequence  of  which  is  a destruction  and  erosion  of 
the  cellular  tissue,  attended  by  inflammation  of  the  skin  and 
neighbouring  parts.  The  tumour  becomes  an  abscess,  and  dis- 
charges matter  rendered  liquid  by  the  process  of  fermentation, 
and  so  acrid  and  irritating,  that  it  extends  the  affection  towards 
all  the  parts  with  which  it  comes  in  contact. 

The  notions  entertained  hitherto  on  cancer,  are,  at  once,  defi- 
cient in  precision  and  accuracy,  and  it  is  to  their  fallacy  that  we 
are  to  attribute  the  number  of  contradictory  opinions  on  the  sub- 
ject of  its  proper  treatment.  Too  precise  a distinction  cannot  be 
laid  down,  between  the  cancerous  or  phagedenic  ulcer,  whose 
seat  is  always  in  the  skin,  or  in  the  mucous  membranes  (which 
being  mere  prolongations  of  the  skin,  retain  much  of  its  struc- 
ture), and  those  cancers  which  affect  the  other  parts  of  the  ani- 


OF  ABSORPTION. 


171 

nial  economy,  especially  the  lymphatic  glands,  the  testicles  and 
the  breasts.  In  the  cancerous  ulcers  peculiarly  frequent  in  the 
face,  the  lips,  the  tongue,  in  the  inner  coat  of  the  stomach,  of  the 
rectum,  and  of  the  uterus,  the  parts,  affected  with  inflammation 
of  a malignant  kind,  are  destroyed,  without  any  means  of  check- 
ing the  progress  of  that  destructive  action,  the  cause  of  which  is 
easily  conceived;  while  in  true  cancer,  the  glandular  tumefaction 
always  precedes  the  cancerous  diathesis.  As  long  as  the  affec- 
tion consists  nierely  in  the  obstruction  of  the  vessels  by  indura- 
ted lymph,  the  tumour  is  indolent,  and  is  yet  only  a schirrus;  but 
soon  all  trace  of  organization  is  lost  in  the  tumefied  part,  the 
ruptured  vessels  are  lost  in  the  mass  of  different  substances;  the 
process  of  fermentation  which  takes  place,  converts  every  part 
into  a grayish  pulpy  substance,  in  which  the  most  expert  eye  can 
discover  no  organization,  and  no  distinction  of  parts.  When- 
ever this  cancerous  destruction  of  parts  occurs,  whether  the 
whole  organ  is  affected,  or  whether  the  disease  extends  only  to 
a few  points,  extirpation  is  the  only  remedy  to  be  eraployed;  it 
is  absolutely  necessary,  that  a surgical  operation  should  rid  the 
constitution  of  a part,  in  which  organization  and  life  no  longer 
exist. 

The  lymphatic  glands  which  swell  in  the  vicinity  of  cancerous 
tumours,  have  already  received,  by  means  of  the  absorbents,  the 
destructive  germ,  and  must  be  removed  with  the  rest  of  the 
diseased  part,  that  the  operation  may  be  attended  with  the 
greater  prospect  of  success.  It  is  very  true,  that  open  cancers 
of  the  breast  may,  for  a long  time,  discharge  putrid  matter, 
without  inducing  a cancerous  affection  of  the  glands  of  the  ax- 
illa. But  may  not  the  discharge,  in  this  case,  act  on  the  princi- 
ple of  revulsion;  and  besides,  what  shall  we  oppose  to  experi- 
ence, which  shows  that  these  glands,  if  not  removed  along  with 
the  cancerous  breast,  soon  become  affected  with  cancer.  If  the 
nature  of  this  work  did  not  circumscribe  me  within  certain 
limits,  I should  point  out  several  other  particulars  relative  to 
the  history  of  cancer;  and  among  other  cases,  in  my  own  prac- 
tice, I should  relate  that  of  a woman,  in  whom  I removed  a 
cancerous  tumour  situated  on  the  left  side  of  the  chest:  this  case 
is  remarkable  from  the  number  of  operations  which  her  disease 


OF  ABSORPTION. 


172 

required,  and  for  which  M.  Pelletan  removed,  six  years  ago, 
the  left  breast,  and,  three  years  ago,  a gland  under  the  axilla  of 
the  same  side. 

The  difference  in  the  termination  of  glandular  swellings  and 
those  arising  from  cancer,  scrophula  or  syphilis,  makes  it  proba- 
ble, that  there  exist  ferments,  or  specific  poisons,  which  dispose 
the  accumulated  matter  to  undergo  peculiar  changes. 

The  venereal  virus,  absorbed  by  the  lymphatics  of  the  organs 
of  generation,  remains,  for  some  time,  in  the  glands  of  the  groin, 
before  it  extends  bevond,  as  is  proved  bv  the  cure  of  the  vene- 
real disease,  by  extirpating  the  diseased  glands.  In  short,  the 
impediment  which  the  lymph  meets  with,  in  passing  through 
the  glands,  shows  why  these  parts  are  so  frequently  the  seat  of 
critical  abscesses,  by  which  we  judge  of  the  nature  of  several 
fevers  of  a malignant  kind.  In  the  plague  of  eastern  countries, 
the  virus  that  occasions  this  dreadful  malady  is  disseminated 
throughout  the  body,  collects  in  the  glands,  is  transmitted 
through  them  with  difficulty,  brings  on  an  irritation  and  gangre- 
nous inflammation,  terminating  in  pestilential  buboes. 

XLVII.  The  thoracic  duct  may  be  considered  as  the  centre 
in  which  the  whole  lymphatic  svstem  terminates;  it  arises  at  the 
upper  part  of  the  abdomen,  from  the  union  of  the  chylous  ves- 
sels with  the  lymphatics  coming  from  the  inferior  extremities. 
At  the  part  where  all  these  vessels  meet,  there  is  a dilatation,  a 
sort  of  ampullula,  called  lumbar  cistern,  receptaculum  chyli  or 
of  Pecquet,  which,  in  truth,  is  not  always  found,  and  the  size  of 
which  is  very  variable.  The  thoracic  duct  enters  the  chest 
through  the  opening  in  the  diaphragm  which  transmits  the 
aorta;  it  then  ascends  along  the  spine,  on  the  right  side  of  the 
aorta,  within  the  posterior  mediastinum.  At  the  upper  part  of 
the  chest,  opposite  to  the  seventh  cerv'ical  vertebra,  it  inclines 
from  the  right  to  the  left  side,  passes  behind  the  oesophagus  and 
the  trachea,  and  opens  into  the  subclavian  vein  of  the  left  side^ 
at  the  back  part  of  the  insertion  of  the  internal  jugular  into  that 
vein.  While  the  thoracic  duct  is  ascending  along  the  spine,  it 
receives  the  lymphatics  of  the  parietes  of  the  chest;  those  of  the 
lungs  enter  it  as  it  passes  behind  the  root  of  these  organs.  In  its 
course  from  the  right  towards  the  left  side,  it  receives  the  ab- 
sorbents of  the  right  upper  extremity,  and  those  of  the  right 
side  of  the  head  and  neck.  Lastly,  it  unites  with  those  vessels 


OF  ABSORPTION. 


173 

which  are  coming  from  the  left  side  of  the  head  and  neck,  as 
well  as  from  the  left  upper  extremity,  just  before  opening  into 
the  subclavian  vein.  The  thoracic  duct  sometimes  has  its  inser- 
tion in  the  jugular  vein  of  the  same  side,  and  not  unfrequently 
the  lymphatics  of  the  right  side  of  the  chest,  neck,  and  head, 
and  of  the  right  upper  extremity,  unite  to  form  a second  duct, 
which  opens  separately  into  the  right  subclavian  vein.*  What- 
ever be  the  vein  into  which  the  duct  opens,  its  structure  is  the 
same  as  that  of  the  lymphatics,  and  its  inner  part  is  furnished 
with  valvular  folds.  Its  increase  of  size  is  not  progressive,  as  it 
approaches  towards  its  termination;  on  the  contrary,  there  are 
seen,  here  and  there,  dilatations  of  different  sizes,  separated  by 
proportionate  contractions.  Sometimes  it  divides  into  several 
vessels  which  inosculate  and  form  lymphatic  plexuses.  The 
opening  at  which  the  thoracic  duct  enters  the  subclavian  vein, 
is  furnished  with  a valve,  better  calculated  to  prevent  the  flow 
of  blood  into  the  lymphatic  system,  than  to  moderate  the  too 
rapid  flow  of  the  lymph  into  the  torrent  of  circulation.  Com- 
pression of  the  thoracic  duct,  in  aneurism  of  the  heart  and  aorta, 
gives  rise  to  several  kinds  of  dropsy,  a disease  always  depend- 
ing on  the  loss  of  equilibrium,  between  the  processes  of  inhala- 
tion and  exhalation,  either  frpm  increased  action  of  the  exha- 
lants,  or  from  the  absorbents  refusing  to  take  up  the  lymph,  in 
consequence  of  obstruction  in  the  glands,  or  of  compression  of 
the  duct. 

XLVIII.  The  nature  of  the  lymph  is  far  from  being  as  well 
understood,  as  that  of  the  vessels  along  which  it  circulates.  Hal- 
ler considers  it  as  very  analogous  to  the  serum  of  the  blood,  and 
says  that  this  substance,  to  which  he  frequently’^  gives  the  name 
of  lymph,  is  like  the  fluid  contained  in  the  absorbents,  slightly 
viscous  and  saltish;  that  heat,  alcohol,  and  the  acids  coagulate 
it;  in  short,  that  it  possesses  all  the  qualities  of  the  albuminous 
fluids.  The  serum  of  the  blood  exhaled,  throughout  the  extent 

* In  some  rare  cases,  lymphatic  vessels,  in  other  parts  of  the  body,  are  seen 
to  open  into  neighbouring-  veins.  This  enables  one  to  account  for  the  presence 
of  the  chyle  which  is  said  to  have  been  found  in  the  meseraic  veins,  into  which 
it  had  been  poured  by  some  lacteal.  Mascagni  was  aware  of  this  anatomical 
fact.  The  lymphatic  system  is,  however,  the  most  subject  to  deviations  of any 
in  the  animal  economy. 


OF  ABSORPTION. 


174 

of  the  internal  surfaces,  and  even  within  the  substance  of  our 
organs,  by  the  capillary  arteries,  is  absorbed  by  the  lymphatics, 
and  is  one  of  the  principal  sources  of  the  lymph,  which  resem- 
bles it  much.  It  may  be  conceived,  however,  that  the  nature  of 
the  lymph  must  be  much  more  compound  than  that  of  the  serum 
of  the  blood,  since  the  lymphatics  which  absorb,  almost  indiscri- 
minately, every  kind  of  substance,  take  up  what  comes  off  from 
our  organs,  and  J^he  recrementitious  parts  of  our  fluids,  and 
these  arc  sometimes  recognisable  in  the  absorbents,  when  mark- 
ed by  striking  qualities,  as  fat  by  its  not  mixing  with  aqueous 
fluids,  and  bile  by  its  deep  yellow  colour. 

The  chyle,  which  is  necessarily  affected  by  the  various  kinds 
of  food  which  we  use,  has  different  appearances  in  the  same  per- 
sons, varying  according  to  the  quality  of  the  different  substances 
on  which  we  feed;  indigo  gives  it  a blue  colour;  it  is  reddened 
by  madder  and  beet-root,  and  is  changed  to  green,  by  the  colour- 
ing matter  of  several  vegetables,  &c.  In  a great  number  of  ex- 
periments performed  on  living  animals,  it  has  always  appeared 
to  me,  such  as  it  is  described  by  authors,  white,  with  a slight 
viscidity,  and  very  like  milk  containing  a very  small  quantity  of 
flour.  It  is  easy  to  collect  a certain  quantity  of  chyle,  by  tying 
the  thoracic  duct  of  a large  dog,  of  a sheep,  or  even  of  a horse, 
as  was  done  several  times  at  the  veterinary  school  at  Alfort. 

This  fluid,  when  exposed  to  the  air,  on  cooling,  separates 
into  two  parts,  the  one  forming  a kind  of  gelatinous  coagulum, 
very  thin  and  not  unlike  the  huffy  coat  of  inflammatory  blood; 
the  other,  in  greater  quantity  and  liquid,  rising  above  the  coagu- 
lum, on  its  being  detached  from  the  sides  of  the  cup  to  which 
it  adheres.  The  coagulated  mass  is  semi-transparent,  of  a light 
pink  colour,  does  not  resemble  the  curd  of  milk,  so  that  all  that 
has  been  said  by  a few  modern  physiologists,  on  the  exact  re- 
semblance which  they  have  pretended  to  discover  between  milk 
and  chyle,  is  totally  void  of  foundation. 

The  lymph,  which  constantly  unites  with  the  chyle  before 
the  latter  enters  the  sanguiferous  system,  on  being  received  into 
a vessel  by  Mascagni,  coagulated  in  the  space  of  seven  or  ten 
minutes,  turned  sour,  and  soon  separated  into  two  parts;  the  one 
more  abundant,  serous,  in  the  midst  of  which  there  floated  a 
fibrous  coagulum,  which  by  contrating,  formed  into  a small 


OF  ABSORPTION. 


175 

cake  on  the  surface  of  the  fluid.  Hence  he  concludes,  contrary 
to  the  opinion  of  Hewson,  that  lymph  consists,  for  the  greatest 
part,  of  serum,  and  that  fibrine  constitutes  its  least  part. 

XLIX.  The  practice  of  surgery  in  a great  hospital,  has 
afforded  me  frequent  opportunities  of  examining  the  lymph 
which  is  discharged,  in  abundance,  from  ulcerated  scrophulous 
tumours,  in  the  groin,  in  the  axilla,  and  in  various  other  parts 
of  the  body.  I have  always  met  with  a liquid  nearly  transparent, 
slightly  saline,  coagulable  by  heat,  alcohol  and  the  acids.  Small 
fibrous  flocculi  form,  even  on  the  surface  of  the  cloths  which 
are  wetted  with  it,  and  show  the  existence  of  two  parts,  the  one 
a gelatino-albuminous  fluid  holding  in  solution  several  salts,  the 
other,  in  smaller  quantity,  is  a fibrous  substance  which  con- 
cretes spontaneously.  The  lymph,  in  man  and  the  warm-blooded 
animals,  appears  to  me,  in  every  respect,  similar  to  the  fluid 
which  is  contained  in  the  vessels  of  white-blood  animals. 


CHAPTER  III. 

ON  THE  CIRCULATION. 

L.  The  term  circulation  is  applied  to  that  motion  by  which 
the  blood,  setting  out  from  the  heart,  is  incessantly  carried  to  all 
parts  of  the  body  by  means  of  the  arteries,  and  returns,  by  the 
veins,  to  the  centre  whence  it  began  its  circuit. 

The  uses  of  this  circulatory  motion  are  to  expose  the  blood 
changed  by  mixing  with  the  lymph  and  the  chyle,  to  the  air  in 
the  lungs  (respiration);  to  convey  it  to  several  viscera  in  which 
it  passes  through  different  steps  of  purification  (secretions);  and 
to  send  it  into  the  organs  whose  growth  is  to  be  promoted,  or 
whose  losses  are  to  be  repaired,  by  the  nutritive  and  animalized 
part  of  the  blood  brought  into  a state  of  perfection  by  these 
successive  processes  (nutrition). 

The  circulatory  organs  are  less  useful  in  elaborating,  than  in 
conveying  the  fluids.  To  form  a just  conception  of  their  uses, 
one  may  compare  them  to  those  workmen  in  a large  manufac- 
tory in  which  various  kinds  of  goods  are  made,  who  are  employ- 
ed in  carrying  the  materials  to  those  who  are  to  work  them;  and  as 


ON  THE  CIRCULATION. 


176 

among  the  latter,  some  finish  the  work,  while  others  prepare 
the  materials,  so  the  lungs  and  the  secretory  glands  are  continu- 
ally occupied  in  separating  from  the  blood  whatever  is  too 
heterogeneous  to  our  nature  to  become  assimilated  to  our  or- 
gans, or  to  afford  them  nourishment. 

To  understand,  thoroughly,  the  mechanism  of  this  function, 
it  is  necessary  to  study  separately  the  action  of  the  heart,  that 
of  the  arteries  which  arise  from  it,  and  lastly  that  of  the  veins 
which  enter  it.  The  union  of  these  three  classes  of  organs 
forms  the  circle  of  the  circulation. 

LI.  Of  the  action  of  the  heart.  In  man  and  in  all  warm- 
blooded animals,  the  heart  is  a hollow  muscle,  the  inner  part  of 
which  is  divided  into  four  large  cavities  which  communicate 
with  one  another;  from  these,  vessels  arise  which  convey  the 
blood  to  all  pares  of  the  body,  and  the  vessels  which  bring  it 
back  from  all  those  parts  likewise  terminate  in  these  cavities. 

The  heart  is  placed  in  the  chest,  between  the  lungs,  above 
the  diaphragm,  whose  motions  it  follows;  it  is  surrounded  by  the 
pericardium,  a dense  and  fibrous  membrane  admitting  of  very 
slight  extension,  closely  united  to  the  substance  of  the  dia- 
phragm, covering  the  heart  and  great  vessels,  without  contain- 
ing them  in  its  cavity,  furnishing  an  external  covering  to  the 
heart  and  bedewing  its  surface  with  a serous  fluid,  which  never 
accumulating,  except  in  disease,  facilitates  its  motion,  and  pre- 
vents its  adhering  to  the  neighbouring  parts.  The  principal  use 
of  the  pericardium,  is  to  fix  the  heart  in  its  place,  to  prevent  its 
being  displaced  into  other  parts  of  the  chest,  which  could  not 
happen,  without  occasioning  a fatal  disorder  in  the  circulation. 
If,  after  having  laid  open  the  chest  of  a living  animal,  by  raising 
the  sternum,  an  incision  is  made  into  the  pericardium,  the  heart 
protrudes  through  the  opening,  and  moves  to  the  right  and  left 
by  bending  itself  on  the  origin  of  the  large  vessels;  the  course  of 
the  blood  is  then  intercepted,  and  the  animal  threatened  with 
immediate  suffocation. 

In  man,  the  heart  is  placed  nearly  towards  the  union  of  the 
upper  third  of  the  body,  with  the  lower  two  thirds;  it  is,  there- 
fore, nearer  to  the  upper  parts;  it  holds  them  under  a more  im- 
mediate control,  and  as  that  organ  keeps  up  the  action  of  all 
the  rest,  by  the  blood  which  it  sends  into  them,  the  parts  above 


ON  THE  CIRCULATION- 


177 

the  diaphragm  have  much  more  vitality  than  the  parts  beneath. 
The  skin  of  the  upper  part  of  the  body,  and  especially  of  the 
face,  has  more  colour  and  is  warmer  than  that  of  the  lower  parts; 
the  phenomena  of  disease  come  on  more  rapidly  in  the  upper 
parts;  they  are,  however,  less  liable  to  put  on  a chronic  character. 

The  bulk  of  the  heart,  compared  to  that  of  other  parts,  is 
larger  in  the  foetus  than  in  the  child  that  has  breathed,  in  short 
men,  than  in  those  of  high  stature.  The  heart  is  likewise  larger, 
stronger,  and  more  powerful  in  courageous  animals  than  in 
weak  and  timid  creatures. 

This  is  the  first  instance  of  a moral  quality  depending  on  a 
physical  disposition  of  parts;  it  is  one  of  the  most  striking  proofs 
of  the  influence  of  the  moral  character  of  man,  on  his  physical 
nature.  Courage  arises  out  of  the  consciousness  of  strength,  and 
the  latter  is  in  proportion  to  the  activity  with  which  the  heart 
propels  the  blood  towards  all  the  organs.  The  inward  sensation 
occasioned  by  the  afflux  of  the  blood,  is  the  more  lively,  and  the 
better  felt,  when  the  heart  is  powerful.  It  is  on  that  account  that 
some  passions,  for  example,  anger,  by  increasing  the  action  of 
the  heart  increase  a hundred  fold  both  the  strength  and  courage, 
while  fear  produces  an  opposite  effect.  Every  being  that  is  feeble, 
is  timorous,  shuns  danger,  because  an  inward  feeling  warns  him 
that  he  does  not  possess  sufficient  strength  to  resist  it.  It  may 
perhaps  be  objected,  that  some  animals,  as  the  turkey  cock  and 
the  ostrich,  possess  less  courage  than  the  least  bird  of  prey;  that 
the  ox  has  less  than  the  lion  and  other  carnivorous  animals. 
What  has  been  said  does  not  apply  to  the  absolute,  but  to  the 
relative  size  of  the  heart.  Now,  though  the  heart  of  a hawk  be 
absolutely  smaller  than  that  of  a turkey  cock,  it  is  nevertheless 
larger,  in  proportion  to  the  other  parts  of  the  animal.  Besides, 
the  bird  of  prey,  like  the  other  carnivorous  animals,  in  part 
owes  his  courage  to  the  strength  of  his  weapons  of  offence. 

Another  objection,  more  specious,  but  not  better  founded,  is 
drawn  from  the  courage  manifested,  on  certain  occasions,  by 
the  most  timid  animals;  for  example,  by  the  hen  in  protecting 
her  young;  from  the  courage  with  which  other  animals  pressed 
by  hunger  or  lust,  surmount  all  obstacles;  but  particularly  from 
the  heroic  valour  of  men  of  the  most  feeble  bodies.  All  these 
facts,  however,  are  only  proofs  of  the  influence  of  the  mind  on 

Z 


ON  THE  CIRCULATION. 


178 

the  body.  In  civilized  man,  the  prejudices  of  honour,  interested 
considerations,  and  a thousand  other  circumstances,  degrade 
the  natural  inclinations  of  man,  so  as  to  make  a coward  of  one 
whose  strength  is  such  as  would  induce  him  to  brave  all  kinds 
of  dangers;  while  on  the  other  hand,  men  whose  organization 
should  render  them  most  timid,  are  inspired  to  perform  the 
most  daring  actions.  But  all  these  passions,  all  these  moral  af- 
fections operate,  only  by  increasing  the  action  of  the  heart,  by 
increasing  the  frequency  and  the  force  of  its  pulsations,  so  that 
it  excites  the  brain  or  the  muscular  system  by  a more  abundant 
supply  of  blood. 

The  heart  is  not  quite  ovoid  in  man  as  it  Is  several  animals, 
nor  is  it  parallel  to  the  vertebral  column,  but  it  lies  obliquely, 
and  is  flattened  towards  the  side  next  the  diaphragm  on  which 
it  rests. 

Of  the  four  cavities  which  form  the  heart,  two  are  In  a mea- 
sure accessory,  viz.  the  auricles;  they  are  small  musculo-mem- 
branous  bags  opposed  to  each  other,  receiving  the  blood  of  all 
the  veins,  and  pouring  that  fluid  into  the  ventricles,  at  the  base  of 
which  the  auricles  are,  as  it  were,  applied.  The  ventricles  are  two 
muscular  bags  separated  by  a partition  of  the  same  nature,  and 
belonging  equally  to  both:  they  form  the  greatest  part  of  the 
heart  and  give  origin  to  the  arteries. 

The  auricle  and  ventricle  on  the  right  side,  are  larger  than 
those  on  the  left.  But  that  difference  of  size  depends  as  much 
on  the  manner  in  which  the  blood  circulates,  at  the  approach  of 
death,  as  on  the  original  conformation  of  the  heart.  On  the 
point  of  death,  the  lungs  expand  with  difficulty,  and  the  blood 
sent  into  them,  by  the  contractions  of  the  right  ventricle,  being 
no  longer  able  to  circulate  through  them,  collects  in  that  cavity, 
flow's  back  into  the  right  auricle,  in  w'hich  the  veins  continue  to 
deposit  blood,  stretches  their  parietes,  and  increases  considera- 
bly the  dimensions  of  those  cavities.  The  capacity  of  the  right 
cavities  is,  however,  originally  greater  than  that  of  the  left,  and  is 
proportioned  to  that  of  the  venous  system  which  opens  into  it.  The 
right  cavities  of  the  heart,  which  might  be  called  its  venous  cavi- 
ties, have  likewise  thinner  parietes  than  the  left  or  arterial,  and, 
in  this  respect,  the  same  difference  is  observed,  as  in  the  parietes 
of  the  arteries  and  veins.  The  right  ventricle  having  to  send  the 


OTf  THE  CIRCULATION. 


179 

blood  destined  to  the  lungs,  to  a very  short  distance,  and  through 
a tissue  easily  penetrated,  requires  but  a moderate  impelling 
force. 

As  will  be  shown,  in  speaking  of  respiration,  a function  of 
which  the  physiological  history  is  not  easily  separated  from  that 
of  the  circulation,  the  heart  may  further  be  considered,  as  form- 
ed of  two  parts  in  contact,  the  one  right  or  venous,  the  other 
left  or  arterial.  Notwithstanding  the  juxta  position  of  these  two 
parts  of  the  same  organ,  they  are  perfectly  distinct,  and  the 
blood  in  each  cavity  is  very  different  from  that  in  the  other. 
The  blood,  in  the  adult,  can  never  pass  immediately  from  the  one 
to  the  other;  the  right  side  of  the  heart  receives  the  blood  of  the 
whole  body  and  transmits  it  to  the  lungs;  the  left  side  of  the 
heart  receives  the  blood  of  the  lungs,  and  distributes  it  over  the 
whole  body,  so  that,  in  a physiological  point  of  view,  the  lungs 
form  a part  of  the  circle  of  the  circulation,  and  serve  as  an  in- 
dispensable medium  between  the  two  divisions  of  the  heart,  and 
as  will  be  seen  hereafter,  their  part  of  the  circle  is  by  no  means 
the  least  important. 

If  there  existed,  between  the  ventricles,  a direct  communica- 
tion, the  venous  blood  would  mix  with  the  arterial,  and  the  union 
of  these  two  fluids  would  muttially  impair  the  qualities  of  each. 
Recent  observations  have  furnished  an  opportunity  of  judging 
of  the  effects  of  such  a communication  between  the  ventricles, 
which  had  been  imagined  by  the  ancients,  but  of  which  no  case 
had  yet  been  met  with.  A man  forty-one  years  of  age,  came  to 
the  Hopital  de  la  Charite,  to  undergo  the  operation  of  litho- 
tomy. He  was  remarkable  for  the  lividity  of  his  complexion,  the 
turgescence  of  the  vessels  of  the  conjunctiva,  and  the  thickness 
of  his  lips,  which,  like  the  rest  of  his  face,  were  of  a dark  colour; 
his  respiration  was  laborious,  his  pulse  irregular,  he  could  not 
utter  two  words  in  succession,  without  taking  breath;  was  obliged 
to  sleep  in  a sitting  posture,  and  was  particularly  remarkable  for 
his  indolence.  This  indolence,  joined  to  great  natural  simpli- 
city, was  such  that  he  had  never  been  able  to  maintain  himself 
without  the  assistance  of  his  wife.  A very  small  quantity  of 
blood  was  taken  from  his  arm,  in  consequence  of  which  his 
pains  were  diminished,  but  his  difficulty  of  breathing  increased, 
was  followed  by  syncope,  and  he  died  from  suffocation.  On 


180 


ON  THE  CIRCULATION. 


opening  his  body,  his  heart  was  found  filled  with  blood,  and  es- 
pecially the  right  auricle,  which  was  considerably  distended;  the 
pulmonary  artery  was  aneurismal,  and  uniformly  distended  from 
the  right  ventricle  to  its  division;  none  of  its  coats  had  yet 
given  way.  The  two  ventricles  of  the  heart  were  of  nearly  the 
same  capacity,  and  the  relative  thickness  of  their  parietes  did  not 
vary  so  much  as  in  health.  The  partition  between  them  contain- 
ed an  opening  of  communication  of  an  oblong  shape,  about  half 
an  inch  in  extent,  and  directed  obliquely  from  below  upwards, 
from  before  backwards,  and  from  left  to  right;  so  that  not  only 
the  direction  of  the  opening,  but  likewise  a kind  of  valve  formed 
in  the  right  ventricle,  by  a fleshy  column,  so  placed  as  to  prevent 
the  return  of  the  blood  into  the  left  ventricle,  clearly  showed, 
that  the  blood  flowed  from  the  left  into  the  right  ventricle,  and 
thence  into  the  pulmonary  artery.  The  ductus  arteriosus,  an 
inch  in  length,  and  large  enough  to  admit  a goose  quill,  allowed, 
as  in  the  foetus,  a free  passage  to  the  blood  from  the  pulmonary 
artery  into  the  aorta.  The  foramen  ovale  was  closed. 

This  singular  conformation  explains,  in  the  most  satisfactory 
manner,  the  phenomena  observed  during  the  life  of  the  patient, 
and  the  organic  affection  of  the  pulmonary  artery.  There  was 
necessarily,  in  this  vessel,  a mixture  of  venous  and  arterial 
blood,  and  this  blood  was  sent  into  it  in  part  by  the  action  of 
the  left  ventricle,  with  an  increased  impetus,  which  accounts  for 
the  aneurism.  The  blood  which  reached  the  lungs  was  already 
vivified,  and  required  less  action  from  that  organ  to  complete 
its  oxydation;  on  the  other  hand,  the  right  auricle  emptied 
itself  with  difficulty,  into  the  right  ventricle,  in  part  filled  with 
the  blood  which  the  left  ventricle  sent  into  it  with  greater  force: 
hence  the  extreme  difficulty  in  the  venous  circulation,  the  livi- 
dity  of  the  complexion,  the  colour  and  the  puffincss  of  the  face, 
the  habitual  and  general  torpor.  This  state  of  languor  and  inac- 
tivity might,  likewise,  depend  on  the  flow  of  the  venous  blood 
into  the  aorta,  along  the  ductus  arteriosus.  It  is  worthy  of  ob- 
servation, however,  that  this  impure  blood  was  not  transmitted 
to  the  brain,  whose  vital  excitement  it  would  not  have  been  able 
to  maintain.  The  lower  extremities  bore  no  proportion  to  the 
upper,  and  this  inequality  analogous  to  what  is  observed  in  the 
foetus,  depended  on  a similar  cause.  This  morbid  preparation 


ON  THE  CIRCULATION. 


181 

was  deposited  by  M.  Deschamps,  in  the  museum  of  the  Ecole 
dc  Medecine  of  Paris,  and  was,  by  their  desire,  modelled  in 
wax.  M.  Beauchene,  junior,  presented  the  same  museum  with 
a similar  preparation,  which  he  procured  from  a subject  in  the 
dissecting  room. 

Several  anatomists  have  paid  attention  to  the  structure  of  the 
heart;  much  has  been  said  on  the  subject  of  the  peculiar  arrange- 
ment of  the  muscular  fibres  which  form  its  parietes;  yet  the  only 
result  that  can  be  obtained  from  all  these  researches  is,  that  it  is 
absolutely  impossible  to  unravel  the  intricacy  of  these  fibres. 
Fibres  of  the  ordinary  structure,  and  crossing  each  other  in  va- 
rious directions,  form  the  two  auricles;  other  and  more  nu- 
merous fibres  form  the  parietes  of  the  ventricles,  reach  from  the 
apex  to  the  base,  extend  into  the  septum  which  divides  them, 
pass  from  the  one  to  the  other  and  are  lost  into  each  other,  in  se*- 
veral  points.  They  are  exceedingly  red,  short,  close,  and  united 
by  a cellular  tissue,  in  which  fat  scarcely  ever  accumulates. 

These  fibres,  forcibly  pressed  against  each  other,  form  a tis- 
sue similar  to  the  fleshy  part  of  the  tongue,  endowed  with  but 
little  sensibility,  but  contractile  in  the  highest  degree.  Vessels 
and  nerves,  in  considerable  number,  if  compared  to  the  bulk  of 
the  heart,  pervade  this  muscular  tissue,  whose  contraction,  what- 
ever in  other  respects  may  be  the  direction  of  its  fibres,  tends  to 
draw  towards  the  centre  of  the  cavities,  every  point  of  their  pa- 
rietes. Lastly,  a very  fine  membrane  lines  the  inner  part  of  these 
cavities,  facilitates  the  flow  of  the  blood,  and  prevents  the  infil- 
tration of  that  fluid. 

LII.  If  we  suppose,  for  a moment,  that  all  the  cavities  of  the 
heart  are  perfectly  emptied  of  blood,  and  that  they  fill  in  succes- 
sion, the  following  may  be  considered  as  the  mechanism  of  the 
circulation  through  the  heart.  The  blood  brought  back  from 
every  part  of  the  body,  and  deposited  into  the  right  auricle,  by 
the  two  venae  cavae,  and  by  the  coronary  vein,  separates  its  pa- 
rietes and  dilates  it  in  every  direction.  The  irritation  attending 
the  presence  of  the  blood,  stimulates  the  auricle  to  contraction; 
this  fluid,  which  is  incompressible,  flows  back,  in  part,  into  the 
veins,  but  it  chiefly  passes  into  the  pulmonary  ventricle,  through 
a large  aperture,  by  means  of  which  it  communicates  with  the 
right  auricle.  The  auricle  after  freeing  itself  of  the  blood  with 


0N-  THE  CIRCULATION. 


which  it  is  filled,  relaxes  and  again  dilates  by  the  accession  of  a 
new  supply  of  this  fluid,  continually  brought  by  the  veins  which 
open  into  it. 

However,  the  right  ventricle,  filled  with  the  blood  which  it  has 
received  from  the  auricle,  contracts  in  its  turn  on  the  fluid 
whose  presence  excites  its  parietes,  and  tends,  in  part,  to  return 
it  into  the  right  auricle,  and  to  send  it  along  the  pulmonary  ar- 
tery. Regurgitation  from  the  ventricle  into  the  auricle,  is  pre- 
vented by  the  tricuspid  valve,  a membranous  ring  surrounding 
the  edge  of  the  opening  of  communication,  and  the  free  edge  of 
which  is  divided  into  three  divisions,  to  which  are  attached 
small  tendons  terminating  into  the  columnae  carneaeof  the  heart. 
These  valves  laid  against  the  parietes  of  the  ventricle,  the  in- 
stant the  blood  passes  into  its  cavity,  recede  from  them  when  it 
contracts,  and  rise  towards  the  auricular  opening.  They  cannot 
be  forced  into  the  auricle,  as  their  free  and  loose  edge  is  kept  in 
its  situation  by  the  columnae  carneae,  which  are  like  so  many 
little  muscles  whose  tendons  inserted  into  the  loose  edges  of  the 
valves,  bind  them  down,  when  the  stream  of  blood  tends  to 
force  those  membranous  folds  towards  the  auricles.  The  three 
divisions,  however,  of  the  tricuspid  valve,  by  rising  towards  the 
auricular  aperture,  return  into  the  auricle  all  the  blood  contain- 
ed in  the  inverted  cone  which  they  form,  immediately  before 
rising.  Besides,  these  three  portions  of  the  tricuspid  valve  do 
not  close  completely  the  aperture,  around  which  they  are  placed; 
they  are  perforated  by  a number  of  small  holes:  a part  of  the  blood, 
therefore,  returns  into  the  auricle,  but  the  greatest  portion  is  sent 
into  the  pulmonary  artery.  The  action  of  this  vessel  begins,  when 
the  parietes  of  the  ventricle  are  in  a state  of  relaxation,  and  the 
blood  would  be  forced  back  into  the  ventricle,  if  the  sygmoid 
valves,  by  rising  suddenly,  did  not  prevent  it.  Supported  on  a 
kind  of  floor  formed  by  three  valves  which  lie  across  the  caliber 
of  the  vessel,  the  blood  pervades  the  tissue  of  the  lungs,  and 
flows  along  the  divisions  of  the  pulmonary  vessels;  from  the  ar- 
teries it  passes  into  the  veins,  and  these,  four  in  number,  deposit 
it  into  the  left  auricle.  This  auricle,  stimulated  by  the  presence 
of  the  blood,  contracts  in  the  same  manner  as  the  right,  part  of 
the  blood  flows  back  into  the  lungs,  but  the  greatest  part  enters 
the  left  ventricle,  which  sends  it  along  the  aorta,  to  every  part  of 


ON  THE  CIRCULATION. 


183 

the  body,  whence  it  returns  to  the  heart  by  the  veins.  The  re- 
turn of  the  blood  into  the  left  auricle  is  prevented  by  the  mitral 
valve,  which  is  similar  to  the  tricuspid^  except  that  its  loose  edge 
is  divided  only  into  two  divisions.  As  soon  as  the  blood  has 
reached  the  aorta,  this  vessel  contracts,  its  sygmoid  valves  fall, 
and  the  blood  is  sent  to  every  part  of  the  body  which  is  supplied 
by  some  of  the  innumerable  branches  of  that  great  artery. 

In  a natural  state,  tjie  circulation  is  not  carried  as  has  been 
just  stated;  and  we  have  supposed  this  successiv'e  action  of  the 
four  cavities  of  the  heart,  only  to  render  more  intelligible  the 
mechanism  of  the  circulation  in  that  organ.  If  we  lay  bare  the 
heart  in  a living  animal,  we  observe,  that  the  two  auricles  con- 
tract at  the  same  time,  that  the  contraction  of  the  ventricles  is 
likewise  simultaneous,  so  that  while  the  auricles  are  contracting, 
to  expel  the  blood  which  fills  them,  the  ventricles  are  dilating  to 
receive  it.  This  successive  contraction  of  the  auricles  and  v'en- 
tricles  is  readily  explained,  by  the  alternate  application  of  the 
stimulus  which  determines  the  action  of  these  cavities.  The 
blood  which  the  veins  bring  into  the  auricles,  does  not  excite 
their  contraction,  till  a sufficient  quantity  has  been  collected. 
While  this  accumulation  is  taking  place,  they  yield,  and  the  re- 
sistance which  is  felt  on  touching  them,  duringtheir  diastole,  de- 
pends, almost  entirely,  on  the  presence  of  the  blood  which  sepa- 
rates and  supports  their  parietes.  The  same  applies  to  the  ven- 
tricles; they  cannot  contract,  until  a sufficient  quantity  of  blood 
is  collected  within  them;  that  there  remains  some  blood  in  these 
cavities,  for  they  are  never  completely  emptied,  is  no  objection 
to  the  theory,  since  this  small  quantity  is  not  sufficient  to  bring 
on  contraction  of  the  heart,  and  is  not  worth  taking  into  account. 

If  I am  asked,  why  the  four  cavities  of  the  heart  do  not  all 
contract  at  once,  I answer,  that  it  is  easier  to  assign  the  final,  than 
the  proximate  cause.  If  the  contraction  of  these  cavities  had  been 
simultaneous,  instead  of  being  successive,  it  is  evident,  that  the 
auricles  could  not  have  emptied  themselves  into  the  ventricles. 
The  alternate  action  is  moreover  absolutely  necessary,  as  the 
heart  any  more  than  the  other  organs,  is  unable  to  keep  up  a per- 
petual action;  the  principle  of  its  motion,  which  is  soon  ex- 
hausted, being  incapable  of  restoring  itself,  except  during  rest. 
But,  as  was  observed  at  the  beginning  of  this  work,  in  speaking 


ON  THE  CIRCULATION. 


184 

of  the  vital  power  and  functions,  the  alternations  of  action  and 
repose  in  organs  which,  like  the  heart,  perform  functions  essen- 
tial to  life,  must  be  extremely  short  in  their  duration  and  at  very 
close  intervals. 

1 he  cavities  of  the  heart,  however,  are  not  entirely  passive 
during  dilatation,  and  the  action  of  that  organ  does  not  wholly 
depend  on  the  excitement  of  the  blood  on  its  parietes,  since  the 
heart  after  it  has  been  torn  from  the  body  of  a living  animal,  pal- 
pitates, its  cavities  contract  and  dilate,  though  quite  emptied  of 
blood,  and  appear  agitated  by  alternate  motions,  which  become 
fainter  as  the  part  gets  cold.*  If  you  attempt  to  check  the  dia- 
stole of  the  heart,  this  organ  resists  the  hand  which  compresses 
it,  and  its  cavities  appear  endowed  with  a power  which  Galen 
termed  puhive;  in  virtue  of  which  they  dilate  to  receive  the 
blood,  and  not  because  they  receive  it.  In  that  respect,  the 
heart  differs  essentially  from  the  arteries,  whose  dilatation  is  oc- 
casioned by  the  presence  of  the  blood,  whatever  some  physiolo- 
gists may  have  said  to  the  contrary.  I have  repeated,  but  unsuc- 
cessfully, the  famous  experiment  by  which  it  is  attempted  to  be 
proved,  that  these  vessels  have  the  power  of  moving  indepen- 
dently of  the  presence  of  the  blood.  An  artery  tied  and  emptied 
of  blood,  contracts  between  the  two  ligatures  and  is  no  longer 
seen  to  move  in  alternate  contractions. 

LIII.  The  heart  manifestly  shortens  Itself,  and  the  base  ap- 
proaches towards  the  apex,  during  the  systole  or  contraction  of 
the  ventricles.  If  it  became  elongated,  as  some  anatomists  hav’e 
thought,  the  tricuspid  and  mitral  valves  would  be  incapable  of 
fulfilling  the  functions  to  which  they  are  destined,  since  the  co- 
lumnae  carneae,  whose  tendons  are  inserted  in  the  edges  of  these 
valves,  would  keep  them  applied  to  the  parietes  of  the  ventri- 
cles. The  pulsations  which  are  felt,  in  the  interval  between  the 
cartilages  of  the  fifth  and  sixth  true  ribs,  are  occasioned  by  the 
apex  of  the  heart  which  strikes  against  the  parietes  of  the  chest. 
In  the  explanation  of  this  phenomenon,  it  is  not  necessary  to  ad- 
mit the  elongation  of  the  heart  during  its  systole;  it  is  sufficient 
to  consider,  that  the  base  of  the  heart,  in  which  the  auricles  are 
situated,  rests  against  the  vertebral  column,  and  that  these  two 

* Both  Haller  and  Senac  found  that,  by  injecting  warm  water  into  the  heart, 
it  could  be  made  to  contract  for  some  time  after  the  death  of  the  animal.  £o. 


ON  THE  CIRCULATION. 


185 


cavities,  by  dilating  at  the  same  time,  and  by  their  inability  to 
move  the  vertebra,  before  which  they  are  situated,  displace  the 
heart,  and  thrust  it  downwards  and  forwards.  This  motion  de- 
pends likewise  on  the  effort  which  the  blood  sent  into  the  aorta 
makes,  to  bring  to  a straight  line  the  curvature  of  that  artery, 
which  re-acts  and  carries  downwards  and  forwards  the  whole 
mass  of  the  heart,  as  it  were,  suspended  to  it. 

The  quantity  of  blood  which  each  contraction  of  the  ventricles 
sends  into  the  aorta  and  pulmonary  artery,  most  probably,  does 
not  exceed  two  ounces  in  each  of  these  vessels.  The  force  with 
which  the  heart  acts  on  the  blood  which  it  sends  into  them,  is  but 
imperfectly  known,  however  numerous  the  calculations  by  which 
it  has  been  endeavoured  to  solve  this  ph)  siological  problem.  In 
fact,  from  Keil,  who  estimates  at  a few  ounces  only,  the  force  of 
the  heart,  to  Borelli,  who  makes  it  amount  to  one  hundred  and 
eighty  thousand  pounds,  we  have  the  calculations  of  Michelot, 
Jurine,  Robinson,  Morgan,  Hales,  Sauvages,  Cheseiden,  &c.; 
but  as  Vicq-d’Azir  observes,  not  one  of  these  calculations  is 
without  some  error,  either  anatomical  or  arithmetical:  hence  we 
may  conclude  with  Haller,  that  the  force  of  the  heart  is  great, 
but  that  it  is  perhaps  impossible  to  estimate  it  with  mathemati- 
cal precision.  If  we  open  the  chest  of  a living  animal,  and  make 
a puncture  in  his  heart,  and  introduce  a finger  into  the  wound, 
pretty  considerable  pressure  is  felt  during  the  contraction  of  the 
ventricles.* 

* The  difficulty  of  determining  the  exact  degree  of  power  exerted  by  the 
heart  is  strikingly  illustrated  by  the  total  disagreement  in  the  estimates  of  dif- 
ferent writers.  Before  we  engage  in  any  calculations  respecting  the  matter, 
the  following  data  should  be  clearly  established. 

1.  The  quantity  of  blood  expelled  from  each  ventricle  at  every  con- 
traction. 

2.  The  degree  of  velocity  with  which  it  is  expelled. 

.2.  The  amount  of  resistance  which  each  ventricle  has  to  overcome  before  it 
can  propel  the  blood  into  its  corresponding  arteries. 

4.  The  effects  of  the  action  of  the  heart  on  the  blood. 

But  these  are  points  which  seem  likely  never  to  be  ascertained  with  any  sort 
of  precision,  and  of  course  our  computations  must  continue  as  heretofore, 
vague  and  conjectural.  All  we  know  with  certainty  on  the  subject  is,  that  the 
heart  is  a muscle  of  great  strength,  as  is  evinced  by  the  phenomena  of  the  cir- 

2 A 


ON  THE  CIRCULATION. 


186 

LIV.  Of  the  action  of  the  arteries.  There  is  no  part  of  the 
body  to  which  the  heart  does  not  send  blood  by  the  arteries,  for 
it  is  impossible  to  make  a puncture,  with  the  finest  needle,  into 
any  of  our  organs,  without  wounding  several  of  these  vessels 
and  causing  an  effusion  of  blood.  The  aortic  arterial  system 
may  be  compared  to  a tree,  whose  trunk,  represented  by  the 
aorta,  having  its  root  in  the  left  ventricle  of  the  heart,  extends 
afar  its  branches,  and  throws  out,  on  every  side,  its  numerous  ra- 
mifications. The  size  of  the  arteries  decreases,  the  farther  they 
are  from  the  trunk  by  which  they  are  given  off.  Their  form,  how- 
ever, is  not  that  of  a cone,  they  are  rather  cylinders  arising 
from  one  another,  and  decreasing  successively  in  size.  As  the 
branches  given  off  by  a trunk,  taken  collectively,  have  a greater 
diameter  than  that  of  the  trunk  itself,  the  capacity  of  the  arterial 
system  increases  with  the  distance  from  the  heart;  hence  it  fol- 
lows, that  as  the  blood  is  continually  flowing  from  a straiter  to 


culation,  and  further,  by  the  fact  that,  if  the  heart  of  a living  animal  be  grasp- 
ed, no  effort  of  the  hand  will  repress  its  action. 

An  inquiry  far  more  interesting  here  presents  itself.  Why,  as  has  beenfre- 
quently  asked,  does  not  the  heart  become  exhausted,  like  other  muscles,  by 
exertion? 

Three  answers  to  this  intricate  question  have  been  attempted,  no  one  of 
which,  however,  is  at  all  satisfactory. 

1.  By  Willis  it  is  maintained  that  the  voluntary  muscles  derive  their  nerves 
from  the  cerebrum,  while  the  cerebellum  supplies  the  heart  and  other  involun- 
tary  muscles;  and  hence  he  infers  that  the  one  set  is  thereby  fitted  for  teinpora' 
ry,  and  the  other  for  permanent,  and  uninterrupted  action. 

Admitting  the  statement  to  be  anatomically  correct,  we  do  not  perceive 
that  it  leads  to  any  such  conclusion.  But  it  is  not  so.  There  are  many  excep- 
tions to  this  alleged  distribution  of  the  nerves. 

2.  By  Stahl,  it  is  imputed  altogether,  to  the  intelligence  of  bis  animamedica, 
a guardian  power,  that  foreseeing  the  danger  to  which  the  system  would  be 
exfiosed  by  any  remission  in  the  action  of  the  heart,  ordains  it  otherwise.  This 
is  all  hypothesis  and  of  the  most  wretched  kind  too:  by  the  adoption  of  which 
we  only  cut  the  knot  tliat  perplexed  us  to  untie. 

3.  By  Haller  it  is  accounted  for  on  the  supposition  of  a larger  share  of  irrita- 
bility being  possessed  by  the  heart.  It  is  to  be  recollected,  that  he  judgfed  of 
the  degree  of  this  property  by  the  duration  of  the  contractile  power  in  a part, 
after  the.  death  of  the  animal.  Taking  this  as  a just  criterion,  it  will  appear 
from  the  experiments  of  Fowler,  that  in  cold-blooded  animals,  at  least,  the  vo- 
luntary muscles  retain  their  irritability  longer  than  the  heart  itself.  The  dif- 
ference, indeed,  in  this  respect  in  any  class  of  animals,  is  so  slight,  that  other 
objections  aside,  the  hypothesis  could  not  be  entertained. — Ed. 


ON  THE  CIRCULATION. 


187 

a wider  channel,  its  course  must  slacken.  The  direction  of  the 
arteries  is  often  tortuous,  and  it  is  observed,  that  the  arteries 
which  are  sent  to  hollow  viscera,  as  the  stomach,  the  uterus  and 
the  bladder,  or  other  parts  capable  of  contracting,  of  stretching, 
and  of  changing  their  dimensions  every  moment,  as  the  lips,  are 
much  the  most  curved,  no  doubt,  that  they  may  by  unfolding 
give  way  to  the  extension  of  the  tissues  into  which  they  are  dis  * 
tributed.  Lastly,  the  arteries  arise  from  one  another,  and  form 
with  the  trunk  or  branch  from  which  they  are  given  off,  an  an- 
gle varying  in  size,  but  which  is  always  obtuse,  and  more  or 
less  acute  towards  the  branch. 

As  the  arteries  recede  from  their  origin,  they  communicate 
together,  and  these  anastomoses  form  arches,  two  branches 
bending  towards  each  other,  and  joining  at  their  extremities,  as 
we  see  in  the  vessels  of  the  mesentery;  sometimes  two  parallel 
branches  meet  at  an  acute  angle,  and  unite  into  one  trunk,  thus 
the  two  vertebrals  join  to  form  the  basilary  artery;  some  com- 
municate by  transverse  branches  which  pass  from  the  one  to 
the  other,  as  is  seen  within  the  skull. 

In  the  anastomoses  of  the  first  kind,  the  columns  of  blood 
flowing  in  contrary  directions,  along  the  two  branches,  meet  at 
the  point  of  union,  and  mutually  repel  each  other;  their  particles 
mingle,  and  lose  much  of  their  motion  in  that  reciprocal  shock. 
The  blood  then  follows  a middle  direction,  and  enters  the 
branches  which  arise  from  the  convexity  of  these  anastomotic 
arches. 

When  two  branches,  unite  to  produce  a new  artery,  of  a 
greater  caliber  than  each  taken  separately,  but  not  so  large  as 
both  together,  the  motion  of  the  blood  becomes  accelerated,  be- 
cause it  passes  from  a more  capacious  into  a straiter  channel,  and 
the  forces  which  determined  its  progression  are  concentrated 
into  one.  Lastly,  the  transverse  anastomoses  are  well  calculated 
to  promote  the  passage  of  the  blood  from  the  one  branch  into 
the  other,  and  to  prevent  congestion  in  the  parts. 

LV.  The  arteries  are  imbedded  in  a certain  quantity  of  cel- 
lular tissue,  are  almost  universally  accompanied  by  correspond- 
ing veins,  by  lymphatics  and  nerves,  and  their  coats  are  thicker 
in  proportion  as  their  caliber  is  smaller.  The  experiments  of 
Clifton  Whittringham  prove,  that  the  parietes  are  stronger  in 


188 


ON  THE  CIRCULATION. 


the  small  than  in  the  large  arteries,  hence  it  is  observed,  that 
aneurisms  are  much  less  frequent  in  the  former.  Their  parietes 
have  sufficient  firmness  not  to  collapse,  when  the  tube  of  the  ar- 
tery is  empty.  They  are  formed  of  three  coats;  the  external  or 
cellular  admits  of  considerable  extension,  and  appears  to  be 
formed  by  the  condensation  of  the  laminae  of  the  cellular  tissue 
which  surrounds  the  artery  and  unites  it  to  the  neighbouring 
parts.  The  second  coat  is  thicker  and  firmer,  of  a yellow  colour, 
and  fibrous,  and  is  by  some  considered  as  muscular*  and  con- 
tractile, while  other  physiologists  merely  allow  it  to  possess  a 
considerable  degree  of  elasticity.  The  longitudinal  fibres,  admit- 
ted by  some  authors  in  the  texture  of  this  second  coat,  cannot  be 
distinguished,  and  their  existence  is  not  necessary  to  account 
for  the  longitudinal  retraction  of  arteries.  In  fact,  this  retraction 
might  depend  on  elasticity,  it  might  likewise  be  occasioned  by 
the  contraction  of  fibres  not  absolutely  circular  nor  longitudinal, 
but  spiral  and  imperfectly  surrounding  the  vessel,  and  crossing 
each  other  in  various  directions.  This  yellow  coat,  thicker  in 
proportion  in  the  smaller  arterial  twigs,  than  in  the  larger 
branches,  and  thicker  in  these  than  in  the  trunks,  is  dry,  hard, 
not  capable  of  much  extension,  and  is  ruptured  by  an  effort  to 
which  the  external  coat  yields  by  stretching.  Lastly,  a third, 
thin,  and  epidermoid  coat  lines  the  inside  of  these  vessels,  and 
seems  less  calculated  to  give  strength  to  the  parietes  of  the  arte- 
ries, than  to  facilitate  the  flow  of  the  blood,  bv  presenting  to  it  a 
smooth,  even,  and  slippery  surface,  continually  moistened  by  a 
serous  exudation  from  the  minute  arteries,  or  vasa  vasorum, 
which  are  distributed  between  these  coats. 

Besides  these  three  coats,  the  great  arteries  receive  a fourth 
from  the  membranes  lining  the  great  cavities;  thus,  the  pericar- 
dium and  the  pleura  in  the  chest,  the  peritoneum  in  the  abdo- 
men, furnish  to  the  different  parts  of  the  aorta,  an  adventitious 
coat  which  does  not  completely  surround  the  vessel. 

* If'in  man  and  the  greater  number  of  animals,  the  yellow  fibres  which  form 
this  coat  differ  greatly  from  muscular  fibres,  they  in  the  elephant  i-esemble 
that  texture  very  completely,  as  I had  an  opportunity  of  observing,  when  1 wit- 
nessed the  dissection  of  the  elephant  that  died  in  the  year  X.  at  the  Museum 
of  Natural  History.  Let  men  of  judgment  decide,  whether  the  analogy  is 
sufficient  to  warrant  our  admitting,  in  the  arteries  of  tlie  human  body,  th* 
existence  of  muscular  fibres. 


ON  THE  CIRCULATION. 


189 

Of  the  three  coats  which  form  the  parietes  of  the  arteries,  the 
fibrous,  though  thicker  than  the  other  two,  offers,  however,  the 
least  resistance.  If  you  take  the  carotid  artery  which,  for  a con- 
siderable space,  does  not  send  ofiF  any  branches,  and  forcibly  in- 
ject into  it  a fluid,  the  internal  and  middle  coat  will  be  torn,  be- 
fore dilatation  has  increased,  by  one  half,  the  caliber  of  the  vessel. 
The  external  coat  resists  the  cause  of  rupture  by  dilating,  and 
forms  a tumour,  and  it  is  only  by  applying  a pretty  considerable 
force,  that  it  can  be  ruptured.  The  experiment  is  attended  with 
the  same  success,  if  performed  with  air  or  any  other  gas.  In 
aneurism,  the  internal  and  fibrous  coats  of  the  arteries,  but 
more  particularly  the  fibrous,  are  ruptured  at  an  early  stage  of 
the  disease,  which  at  that  period  increases  suddenly,  in  a very 
rapid  manner;  and  on  opening  the  tumour,  it  is  observed,  that 
the  sac  is  entirely  formed  by  the  dilated  cellular  coat.  Take  an 
artery  of  a certain  caliber,  for  example,  the  carotid  or  humeral, 
apply  a ligature  around  it  and  tighten  it  with  some  degree  of 
force.  Dissect  and  take  out  the  vessel,  then  cut  the  thread,  and 
examine  the  place  to  which  it  was  applied,  you  will  observe,  that 
the  parietes  of  the  artery  are  in  that  part  thinner,  and  formed 
merely  by  the  cellular  coat,  which  alone  has  withstood  the  con- 
striction. Take  hold  of  the  two  ends  of  an  insulated  arterial  tube 
and  stretch  it,  then  examine  its  inner  coat,  and  you  will  find  it 
torn  and  cracked  in  several  places,  and  the  parietes  of  the  artery 
evidently  weakened. 

LVI.  This  want  of  extensibility  in  the  coats  of  arteries,  is  the 
principal  cause  of  aneurism;  hence  the  popliteal  artery  is  so  lia- 
ble to  that  affection,  from  its  situation  behind  the  knee,  whose 
extension  is  limited  merely  by  the  resistance  of  the  posterior 
tendons  and  ligaments;  this  artery  is  affected  by  the  jar  which 
takes  place  through  all  the  soft  parts,  when  the  leg  is  violently 
extended;  and  being  less  extensible  than  the  other  parts,  its  inner 
coat  is  ruptured,  or  at  least  weakened,  so  as  to  occasion  an  aneu- 
rism, always  rapid  in  its  progresss.  Of  ten  popliteal  aneurisms 
which  I have  seen  in  different  hospitals,  eight  were  ascribed  to 
a violent  extension  of  the  ham.  In  looking  over  the  cases  that 
have  been  recorded,  it  will  be  seen,  that  a considerable  number 
of  aneurisms  of  the  aorta  have  been  occasioned  by  too  forcible 


ON  THE  CIRCULATION. 


190 

and  too  sudden  an  extension  of  the  trunk  in  raising  a heavy 
burthen. 

From  the  dryness,  the  frailty  of  the  yellow  or  fibrous  coat  of 
arteries,  the  application  of  ligatures  to  these  vessels  is  attended 
with  a speedy  laceration  of  their  tissue;  a moderate  degree  of 
compression  is  sufficient  to  rupture  that  coat,  the  external  and 
internal  remaining,  at  the  same  time,  uninjured,  provided  the 
constriction  be  not  excessive.  Why  is  the  arterial  tissue  almost 
the  only  one  on  which  ligatures  require  to  be  applied,  the  least 
fitted  of  all  the  organic  tissues  to  bear  them?  This  inconvenience 
attending  the  ligature  of  arteries,  led  Pouteau  to  prefer  tying 
arteries  so  as  to  include  the  surrounding  soft  parts  within  the 
ligature,  though  this  process  is,  in  other  respects,  less  eligible. 
The  objections  will  be  obviated,  by  employing  flat  ligatures, 
which,  by  acting  on  a greater  surface  of  the  artery,  are  less  likely 
to  divide  the  coats  of  the  vessel,  which  will  become  obliterated 
at  the  spot  to  which  the  ligature  is  applied,  the  more  rapidly  as 
the  patient  is  younger  and  stronger. 

I once  saw,  in  a man  whose  thigh  was  amputated,  on  account 
of  caries  of  the  knee  joint  combined  with  a scorbutic  affection, 
hemorrhage  attend  the  fall  of  the  ligatures,  which  did  not  come 
away  till  nineteen  days  after  the  operation;  as  if  the  fibrous  coat 
of  these  arteries,  partaking  In  the  debility  of  the  muscular  or- 
gans, had  not  preserved  a sufficient  degree  of  contractile  power 
to  close  the  cavity  of  the  vessel. 

LVII.  The  contractile  power  of  the  arteries  is  in  their  mid- 
dle coat,  it  is  greater,  as  this  coat  is  thicker  in  proportion  to  the 
caliber  of  the  artery.  Hence,  as  Hunter  observes  in  his  work  on 
the  blood  and  inflammation,  the  larger  arteries  are  endowed 
with  elasticity  merely,  while  on  the  other  hand,  contractility  is 
very  apparent  in  those  of  a smaller  caliber,  and  is  found  com- 
plete in  the  capillary  vessels.*  It  is  owing  to  this  that,  in  the 

* This  is  not  altogether  correct.  Every  portion  of  the  arterial  system  is  un- 
questionably possessed  of  the  property  of  contractility.  In  the  larger  vessels, 
muscular  fibres  are  even  demonstrable  to  the  eye.  Besides,  mere  elasticity  will 
not  explain  many  of  the  phenomena  of  arteiial  action.  Contrary  to  the  doctrine 
of  Mr.  Hunter,  it  was  maintained  by  Baron  Haller,  and  indeed  by  almost  all 
the  cotemporary  physiologists,  that  contractility  belongs  exclusively  to  the 
large  and  middle  sized  arteries.  In  this  however  they  were  deceived. 

It  is  now  well  ascertained,  that  muscularity  increases  exactly  as  the  vessel 


ON  THE  CIRCULATION. 


191 


trunks  near  the  heart,  the  progression  of  the  blood  is  effected, 
chiefly  by  the  impulse  which  it  receives  from  the  heart,  and  as 
Lazarus  Riviere  observed,  the  circulation  of  the  blood  in  the 
large  vessels  is  more  an  hydraulic  than  a vital  phenomenon. 
The  action  of  the  main  arterial  trunks,  near  the  heart,  has  so  lit- 
tle influence  on  the  motion  of  the  blood  sent  into  them  by  that 
organ,  that  the  aorta  is  frequently  ossified,  without  affecting  the 
circulation.  The  aorta  is  naturally  bony  in  the  sturgeon.  J.  L. 
Petit,  in  the  case  of  a bookseller  whose  leg  he  had  taken  off, 
found  all  the  arteries  of  a certain  caliber  in  a state  of  ossifica- 
tion; they  were  indurated,  and,  of  course^  incapable  of  acting, 
in  the  slightest  degree,  on  the  column  of  blood  which  flowed 
along  them.  All  these  facts  seem  conclusive  arguments  in  favour 
of  those  physiologists,  who  explain,  on  the  principle  of  elasti- 
city, the  contraction  of  arteries.  But  however  correct  this  ex- 
planation may  be,  with  regard  to  the  vessels  near  the  heart,  it 
does  not  apply  to  the  capillaries;  the  influence  of  that  organ  does 
not  operate  on  these  vessels.  One  may  easily  conceive,  that  the 
column  of  blood  which  by  the  impulse  it  has  received,  in  the 
first  instance,  has  been  sent  along  the  whole  length  of  tubes 
"whose  sides  are  ossified,  inflexible,  and  consequently  inert,  on 
reaching  the  extremity  of  these  canals,  is,  in  a manner,  again 
taken  up  by  the  vital  power  residing  in  the  capillary  vessels,  and 
circulates  from  the  influence  of  the  action  belonging  to  these  ves- 
sels. Besides,  elasticity,  however  considerable,  merely  restores 
those  tissues  that  have  been  stretched,  to  the  condition  in  which 
they  were  before  extension.  Elasticity  is  a kind  of  re-action, 
proportionate  or  relative  to  the  action  which  precedes  it.  Why 
do  arteries  in  the  living  body  contract  to  such  a degree,  that 
when  empty,  their  canal  becomes  obliterated,  while  in  the  dead 
body,  however  perfect  the  depletion  of  the  arterial  system  may 
have  been,  the  cavity  of  the  arteries  remains  perfectly  open. 
Several  physiologists,  however,  and  those  among  the  most 
modern,  consider  elasticity  as  the  principal  cause  of  the  progres- 
sion of  the  blood  along  the  arteries.* 

recedes  from  the  heart,  the  capillaries  having  it  in  the  greatest  degree.  As  far 
as  I know,  this  opinion  was  originally  taught  by  Cullen,  and  afterwards  fullv 
confirmed  by  tire  experiments  of  Hunter. — Ed. 

* It  has  always  been  a matter  of  controversy  among  physiologists,  whether 


ON  THE  CIRCtJLATION. 


192 

As  the  distance  from  the  centre  increases,  the  circulation 
slackens,  from  several  causes,  and  the  blood  could  not  reach  all 
the  parts  of  the  body,  if  the  arteries,  whose  vitality  increases 
with  their  distance  from  the  heart,  and  as  they  become  smaller, 
did  not  propel  it  to  all  the  organs.  The  causes  which  retard  the 
circulation  of  the  arterial  blood,  are,  the  increased  dimensions 
of  the  space  in  which  it  is  contained;— the  resistance  from  the 
curves  of  the  vessels; — the  friction  which  it  undergoes,  and 
which  increases,  as,  at  a distance  from  the  heart,  the  canals  along 
which  it  circulates  increase  in  number;  and  lastly,  the  deviations 
which  the  blood  meets  with  in  its  course,  from  the  trunks  into 
the  branches,  which,  coming  off  sometimes  almost  at  right  an- 
gles, divert  it  from  its  original  direction. 

Several  physiologists  have  called  in  question  this  progressive 
slackening  of  the  flow  of  arterial  blood,  and  several  among 
them,  who  reject  entirely  the  application  of  the  physical  sciences 

the  blood  is  propelled  by  tbe  heart  only,  or  whether  the  arteries  co-operate  to 
the  same  end.  It  is  well  known  that  the  illustrious  Harvey,  the  discoverer 
of  the  circulation,  was  of  the  former  opinion,  and  that  he  has  since  been  sup- 
portedby  many  followers.  We  admit,  atonce,  thitthe  heart  is  the  chief  organ 
concerned,  but  it  seems  to  us  equally  true  that  the  arteries  also  exercise  a 
considerable  agency,  most  commonly  as  auxiliary  to  the  heart,  yet  sometimes 
to  a certain  extent  independently  of  that  organ.  These  two  positions  are  de- 
monstrable, both  by  experiment  and  fact. 

1.  It  has  been  proved  that  the  muscular  power  is  inherent  in  all  the  arteries 
of  the  body,  in  the  large  and  the  small,  in  the  main  trunks  as  well  as  in  tlie 
capillary  extremities. 

2.  That  the  arteries  contract  with  considerable  force,  the  natural  and  un- 
avoidable effect  of  which  must  be,  the  propulsion  of  tlie  blood,  and  the  quick- 
ening of  the  circulation. 

3.  That  the  circulation  has  been'maintained  in  the  feetus,  though  utterly 
destitute  of  a heart.  Cases  of  this  description  are  recorded  in  sufficiently  num - 
ber,  to  put  the  fact  beyond  a doubt.  It  may  however  be  alleged,  that  in  these 
instances,  as  very  often  happens  in  the  history  of  the  animal  economy,  the 
want  of  one  organ  is  supplied  by  the  assumption  of  new,  or  increased  powers 
by  some  other.  We  do  not  perceive  much  force  in  this  objection,  but  as  it  might 
be  raised,  we  will  appeal  to  other  facts  of  a less  disputable  nature,  such  as  are 
afforded  by  the  phenomena  of  local  inflammation,  active  hsemorrhages,  blush- 
ing, hectic  suffusion,  and  many  more  which  it  would  be  easy  to  enumerate. 
Enough  however  have  been  mentioned  to  show  that  the  circulation  may  be 
increased  in  a particular  part  without  its  being  generally  affected,  and  conse- 
quently that  the  heart  is  not  the  only  power  which  propels  the  blood,  but  that 
this  force  also  resides,  in  a limited  degree,  in  the  arteries, — Ed- 


ON  THE  CIRCULATION. 


193 

to  that  of  the  animal  economy,  have,  nevertheless,  supported 
their  opinion  by  a fact  taken  from  hydraulics.  To  give  any  cer- 
tainty to  these  calculations,  respecting  the  impediments  to  the 
circulation  of  the  blood  in  the  arteries,  it  would,  they  say,  be  ne- 
cessary, that  the  arteries  should  be  empty  at  the  instant  when 
they  receive  the  jet  of  blood  sent  into  them  by  the  contraction 
of  the  ventricles.  This,  however,  is  not  the  case;  the  arteries  are 
always  full,  the  blood  flows  along  all  of  them  with  the  same  de- 
gree of  velocity.  This  system  of  vessels  may  be  compared  to  a 
syringe,  from  which  a number  of  straight  and  tortuous  tubes 
should  arise;  each  of  these  would  throw  out  the  fluid  with  an 
equal  degree  of  velocity,  on  applying  pressure  to  the  piston. 

In  refuting  this  doctrine,  I must  take  notice  of  the  manifest 
contradiction  of  pretending  to  exclude,  absolutely,  all  application 
of  the  principles  of  mechanics  to  physiology,  and  the  complete 
application  of  these  principles  to  the  phenomena  of  the  animal 
economy.  This  contradiction,  however,  is  not  more  surprising 
than  that  of  authors  who  exclaim  against  the  abuse  of  modern 
nomenclatures,  and  who,  nevertheless,  eagerly  embrace  every 
opportunity  of  adding  to  it,  by  assigning  new  names  to  such 
parts  as  may  have  escaped  the  attention  of  the  new  nomencla- 
tors.  \^hat  resemblance  is  there  between  a forcing  pump  whose 
sides  are  unyielding,  as  well  as  those  of  the  tubes  which  might 
arise  from  it,  and  the  aorta  which  dilates  every  time  the  blood  is 
sent  into  it;  and  again,  what  resemblance  is  there  between  tubes 
which  decrease  towards  their  open  extremities,  while  the  space 
contained  in  the  arterial  tube  constantly  enlarges,  from  the  innu- 
merable divisions  of  the  vessels.  Since  it  is  admitted,  that  the 
course  of  the  blood  is  slower  in  the  capillarj^  vessels,  must  not 
this  resistance,  opposed  to  the  blood  which  fills  the  series  of  ves- 
sels from  the  capillaries  to  the  heart,  be  felt  more  at  a greater 
distance  from  that  organ,  &c.?  Without  this  progressive  increase 
of  resistance,  as  the  arterial  blood  is  at  a greater  distance  from 
the  heart,  this  fluid  would  flow  along  the  arteries,  as  it  does 
along  the  veins,  without  any  pulsations;  for  this  resistance, 
which  causes  the  lateral  effort  of  dilatation  effected  by  the  blood 
on  the  parietes  of  the  arteries,  is  the  principal  cause  of  the  pulse, 
which  belongs  only  that  set  of  vessels.  A very  remarkable  dif. 
ference  is  observable,  between  the  blood  which  is  sent  to  the 

2 B 


194 


ON  THE  CIRCULATION. 


toes,  and  that  which  goes  to  the  mammse,  as  I have  several 
time  noticed  in  removing  the  carious  bones  of  the  toes,  or  in 
extirpating  cancerous  breasts;  the  small  arteries  of  these  parts 
are  nearly  of  the  same  size;  but  the  jet  of  blood  is  much  more 
rapid,  the  blood  is  sent  to  a much  greater  distance,  when  one  of 
the  mammary  arteries  is  divided. 

The  re-action  of  the  arteries  on  the  blood  which  dilates  them, 
depends  not  only  on  the  great  elasticity  of  their  parietes,  but 
likewise  on  the  contractility  of  the  muscular  coat.  Elasticity  has 
a considerable  share  in  the  action  of  the  larger  trunks,  while  con- 
tractility is  almost  the  sole  agent  in  producing  the  action  of  the 
minute  arteries.  If  a finger  is  introduced  into  the  artery  of  a 
living  animal,  its  parietes  compress  it  in  every  direction;  if  the 
blood  is  prevented  from  flowing  in  it,  the  canal  becomes  obli- 
terated by  the  adhesion  of  its  parietes,  and  the  vessel  is  con- 
verted into  a ligamentous  cord,  such  as  that  formed  in  the 
adult,  by  the  remains  of  the  umbilical  arteries  and  veins.  This 
contractility  which,  during  life,  is  always  in  action,  keeps  the 
arteries,  distended  by  the  blood  which  fills  them,  of  a smaller 
caliber  than  after  death.  In  performing  capital  operations,  es- 
pecially in  the  amputation  of  limbs,  I have  always  found  the 
arteries,  whether  filled  with  blood  or  empty,  much  smaller  than 
I should  have  expected  from  their  appearance  in  the  dead  body. 

It  happens,  however,  sometimes,  that  the  quantity  of  blood 
sent  to  an  organ  increases,  in  consequence  of  some  cause  of  irri- 
tation; the  caliber  of  the  arteries  of  the  part,  then  becomes  re- 
markably enlarged.  Thus,  the  arteries  of  the  uterus,  which  are 
very  small  in  its  unimpregnated  state,  acquire,  towards  the  end 
pregnancy,  a caliber  equal  to  that  of  the  radial  arterj’:  the 
small  arteries  which  are  sent  to  the  mammae,  are  not  in  the 
same  condition,  as  I have  had  an  opportunity  of  ascertaining  in 
a woman  who  had  been  suckling  a child  for  two  months  before 
her  death;  they  retained  their  almost  capillary  minuteness,  which 
would  seem  to  prove,  that  the  lymphatics  are  alone  concerned 
in  bringing  to  these  glands  the  materials  of  their  secretion.  The 
mammary  arteries  are  evidently  enlarged  in  open  cancer  of  the 
breast;  in  cancer  of  the  penis,  the  blood-vessels  likewise  become 
enlarged;  hence  in  removing  the  penis  for  that  aflFection,  it  is 
absolutely  necessary  to  secure  the  arteries  with  ligatures,  a pre- 


ON  THE  CIRCULATION. 


195 


caution  which  need  not  be  attended  to,  in  a case  of  gangrene. 
Gangrene  is  attended  with  this  peculiarity,  that  the  arteries  of 
the  mortified  parts  contract,  so  as  to  become  obliterated,  when 
their  caliber  is  inconsiderable. 

As  the  arteries  are  the  canals  which  convey  to  all  our  organs 
the  materials  of  growth  and  reparation,  they  are  larger,  in  pro- 
portion, in  children,  in  whom  nutrition  is  more  active,  and  their 
caliber  is  always  proportionate  to  the  natural  or  morbid  de- 
velopment of  organs:  hence  the  descending  aorta  and  the  iliac 
arteries  are  larger  in  women  than  in  men;  hence  the  right  sub- 
clavian artery,  which  conveys  blood  to  the  larger  and  more 
powerful  of  the  two  upper  extremities,  because  the  more  em- 
ployed, is  larger  than  the  left  subclavian.  But  the  effect  should 
not  be  mistaken  for  the  cause,  and  it  should  not  be  imagined, 
that  the  right  upper  extremity  owes  its  superiority  to  the  greater 
caliber  of  its  artery.  In  the  new  born  child,  this  vessel  is  not 
larger  than  the  left  subclavian;  but  the  right  arm  being  more 
frequently  employed,  the  distribution  of  the  fluids  takes  place 
more  favourably,  nutrition  is  carried  on  with  more  energy,  it 
acquires  more  bulk  and  strength,  and  therefore  the  right  subcla- 
vian artery  conveys  blood  to  it  by  a wider  channel.  If  the  left 
upper  extremity  were  employed  in  the  same  manner,  and  if  the 
right  were  kept  in  a state  of  inaction,  the  left  subclavian  would, 
no  doubt,  exceed  the  right.  I am  warranted  by  two  facts,  in 
forming  this  conjecture.  In  dissecting  the  bodies  of  two  men 
that  were  left-handed,  I observed  in  the  left  subclavian  arteries, 
the  same  proportionate  enlargement  which  is  usually  met  with 
in  the  same  vessels  on  the  right  side. 

LVIII.  As  the  arteries  are  always  full  during  life,  and  as 
the  blood  flows  along  them  with  less  velocity,  the  greater  their 
distance  from  the  heart,  the  blood  which  the  contractions  of  the 
left  ventricle  send  into  the  aorta,  meeting  the  column  of  blood 
already  in  that  vessel,  communicates  to  it  tho  impulse  which  it 
has  received;  but  retarded  in  its  direct  progression  by  the  re- 
sistance of  that  column,  it  acts  against  the  parietes  of  the  vessels, 
and  removes  them  to  a greater  distance  from  their  axis.  This 
lateral  action  which  dilates  the  arteries,  depends,  therefore,  on 
the  resistance  of  the  parietes  of  these  cavities,  always  filled  with 
blood,  to  that  which  the  heart  sends  into  them.  This  dilatation, 


ox  THE  CIRCULATION 


196 

which  is  more  considerable  in  the  large  arteries  than  in  the 
smaller  ones,  manifests  itself  by  a beat,  known  under  the  name 
of  pulse.  The  experiments  of  Lamure  would  lead  one  to  believe, 
that  another  cause  of  this  phenomenon  is  a slight  displacement 
of  the  arteries,  every  time  they  dilate.  These  displacements  are 
most  easily  observed  at  their  curvatures,  and  where  they  adhere 
to  surrounding  parts,  by  a loose  and  yielding  cellular  tissue. 

The  pulse  is  more  frequent  in  women,  in  children,  in  persons 
of  small  stature,  during  the  influence  of  the  passions,  and  under 
violent  bodily  exercise,  than  in  an  adult  man,  of  high  stature, 
and  of  a calm  physical  and  moral  nature.  At  an  earlv  period  of 
life,  the  pulse  beats  as  often  as  a hundred  and  forty  times  in  a 
minute.  But  as  the  child  gets  older,  the  motion  of  the  circula- 
tion slackens,  and  at  two  5'ears  old,  the  pulse  beats  only  a hun- 
dred times  in  the  same  space  of  time.  At  the  age  of  puberty, 
the  beats  of  the  pulse  are  about  eighty  in  a minute;  in  manhood, 
seventy-flve,  and  lastly,  in  old  men  of  sixty,  the  pulse  is  not 
above  sixty.  It  is  slower  in  the  inhabitants  of  cold,  than  in  those 
of  warm  climates. 

Since  the  time  of  Galen,  the  pulse  has  furnished  physicians 
with  one  of  their  principal  sources  of  diagnosis.  The  force,  the 
regularity,  the  equality  of  its  pulsations,  opposed  to  their  weak- 
ness, inequality,  irregularity,  and  intermittence,  afford  the  means 
of  judging  of  the  nature  and  danger  of  a disease,  of  the  power 
of  nature  in  bringing  about  a cure,  of  the  organ  that  is  most 
affected,  of  the  time  or  period  of  the  complaint,  &c.  No  one 
has  been  more  successful  than  Bordeu,  inthe  consideration  of 
the  pulse,  under  these  different  points  of  view.  Its  modifications 
indicative  of  the  periods  of  diseases,  establish,  according  to  that 
celebrated  physician,  as  may  be  seen  in  his  Recherches  sur  le 
pouls  par  rapport  aux  crises^  the  pulse  of  crudity^  of  irritation, 
and  of  concoction.  Certain  general  characters  indicate,  whether 
the  affection  is  situated  above  or  below  the  diaphragm,  hence 
the  distinction  of  superior  and  inferior  pulse.  Lastly,  peculiar 
characters  denote  the  lesion  of  peculiar  organs;  which  constitutes 
the  nasal,  guttural,  pectoral,  stomachic,  hepatic,  intestinal,  renal, 
uterine,  &c. 

Besides  these  sensible  beats,  which  constitute  the  pheno- 
menon of  the  pulse  in  the  arteries,  there  is  an  inward  and  obscure 


ON  THE  CIRCULATION, 


197 

pulsatory  motion,  by  which  all  the  parts  of  the  body  are  agitated, 
every  time  that  the  ventricles  of  the  heart  contract.  There  is  a 
kind  of  antagonism  between  the  heai  t and  the  other  organs,  they 
yield  to  the  impulse  which  it  gives  to  the  blood,  dilate  on  re- 
ceiving this  fluid,  and  collapse  when  the  effort  of  contraction  is 
over.  Every  part  vibrates,  trembles,  and  palpitates  within  the 
body,  the  motions  of  the  heart  shake  its  whole  mass,  and  these 
quiverings,  which  may  be  observed  externally,  are  most  mani- 
fest when  the  circulation  is  carried  on  with  rapidity  and  force. 
In  some  head  aches,  the  internal  carotid  arteries  pulsate  with 
such  violence,  that  not  only  the  ear  is  sensible  to  the  noise  made 
by  the  column  of  blood  striking  against  the  curvature  of  the 
osseous  canal,  but  the  head  is  evidently  moved  and  raised,  as  it 
were,  at  each  pulsation.  If  you  look  at  your  hand  or  foot,  when 
the  upper  or  lower  extremity  is  quiescent  and  pendulous,  you 
will  observe  in  it  a slight  motion  corresponding  to  the  beats  of 
the  heart.  This  motion  increases,  and  even  makes  the  hand 
shake,  when,  from  the  influence  of  the  passions,  or  from  violent 
exercise,  the  circulation  is  accelerated;  in  every  violent  emotion 
we  feel,  within  ourselves,  the  effort  by  which  the  blood,  at  each 
beat  of  the  pulse,  penetrates  into  our  organs  and  fills  every  tissue. 
And  it  is,  in  a great  measure,  from  this  inward  tact,  that  we  are 
conscious  of  existence:  a consciousness  the  more  lively  and  dis- 
tinct, as  the  effect  of  which  we  are  speaking  is  more  marked.  It 
is,  likewise,  from  observing  this  phenomenon,  that  several  phy- 
siologists have  been  led  to  conceive  the  idea  of  a double  motion, 
which  dilates  or  condenses,  which  contracts  or  expands,  alter- 
nately, all  organs  endowed  with  life;  they  have  observed,  that 
dilatation  prevails  in  youth,  in  inflammation  and  erection,  con- 
ditions of  which  all  parts  are  capable,  according  to  their  differ- 
ence of  structure. 

LIX.  At  the  moment  when  the  left  ventricle  contracts,  to 
send  the  blood  into  the  aorta,  the  sigmoid  valves  of  that  artery 
rise,  and  apply  themselves  to  its  parietes,  without,  nevertheless, 
closing  the  orifices  of  the  coronary  arteries,  which  lie  above  the 
loose  edges  of  the  valves;  so  that  the  blood  is  received  into  these 
vessels,  at  the  same  time  as  into  the  others.  When  the  contraction 
of  the  ventricle  is  over,  the  aorta  acts  on  the  blood  which  it  con- 
tains, and  would  send  it  back  into  the  ventricle,  if  the  valves,  by 


198 


ON  THE  CIRCULATION. 


suddenly  descending,  did  not  present  an  insuperable  obstacle  to 
the  return  of  the  blood,  and  did  not  yield  a point  of  resistance 
to  the  action  of  the  whole  arterial  system ; only  the  small  quan- 
tity of  blood  below  the  valves,  at  the  moment  of  their  descend- 
ing, flows  back  towards  the  heart,  and  returns  into  the  ventricle. 

Though  the  rate  at  which  the  blood  flows  along  the  aorta,  has 
been  estimated  at  only  about  eight  inches  in  a second,  a pulsa- 
tion is  felt  in  all  the  arteries  of  a certain  caliber,  at  the  instant 
the  ventricles  are  contracting.  The  reason  that  the  pulsations  of 
the  heart  appear  to  take  place  at  the  same  time  as  those  of  the 
arteries,  is,  that  the  columns  of  blood,  in  these  vessels,  receive 
an  impulse  from  that  which  is  issuing  from  the  ventricles,  and 
this  concussion  is  felt  in  an  instant  of  time,  too  short  to  be  mea- 
sured, such  as  that  which  is  felt  by  the  hand  applied  to  the  end 
of  a piece  of  timber  struck,  at  the  other  end,  with  a hammer. 
The  blood  which  fills  a main  trunk,  supplies  to  each  of  the 
branches  which  arise  from  it,  columns  proportionate  to  their  cali- 
ber. This  division  of  the  principal  column  is  effected  by  a kind 
of  projection  at  the  mouth  of  each  artery.  These  internal  projec- 
tions detach  from  the  main  stream  the  lesser  ones,  and  these  flow 
the  more  readily  into  the  branches,  according  as  these  arise 
from  the  trunk  at  a more  acute  angle,  as  the  projection  is  more 
prominent  and  the  deviation  of  the  fluid  less  considerable.  If 
the  branches  are  given  off  at  an  almost  right  angle,  the  orifices 
of  the  arteries  scarcely  project  at  all,  and  nothing  but  the  effort 
of  lateral  pressure  determines  the  flow  of  the  blood  into  them. 

The  flow  of  the  blood  into  the  arteries  which  are  distributed 
to  muscles,  is  not  interrupted  when  these  muscles  contract,  for 
whenever  arteries,  of  a certain  caliber,  penetrate  into  muscles, 
they  are  surrounded  by  a tendinous  ring,  which,  during  the  con- 
traction of  the  muscle,  becomes  enlarged,  from  the  extension  in 
every  direction,  effected  by  the  fibres  which  are  attached  to  it, 
around  its  circumference.  The  existence  of  this  truly  admirable 
conformation,  may  be  readily  ascertained,  by  observing  the 
aorta,  in  its  passage  through  the  crura  of  the  diaphragm;  the 
perforating  arteries  of  the  thigh,  where  they  enter  at  the  back 
part  of  the  limb  into  the  adductor  muscles;  the  popliteal,  as  it 
pisses  through  the  upper  extremity  of  the  soleus  muscle. 


ON  THE  CIRCULATION. 


199 


LX.  Of  the  capillary  vessels.  The  arteries,  after  dividing 
into  branches,  these  branches  into  lesser  ones,  and  these  into 
progressively  smaller  ramifications,  terminate  in  the  tissue  of 
our  organs,  by  becoming  continuous  with  the  veins.  The  ve- 
nous system  arises,  therefore,  from  the  arterial  system,  the  ori- 
gins of  the  veins  being  merely  the  more  minute  extremities  of 
the  arteries,  which  becoming  capillary  from  the  great  number 
of  divisions*  they  have  undergone,  bend  in  an  opposite  direc- 
tion and  become  altered  in  their  structure. 

These  minute  capillary  arteries  form  with  the  minute  veins, 
with  which  they  are  continuous,  and  with  the  lymphatics,  won- 
derful meshes  in  the  tissue  of  our  organs. 

Several  physiologists  consider  the  capillary  blood  vessels,  as 
an  intermediate  system  between  the  arteries  and  veins,  in  which 
the  blood,  entirely  out  of  the  influence  of  the  action  of  the  heart, 
flows  slowly,  with  an  oscillatory  and  sometimes  retrograde  mo- 
tion, is  no  longer  red,  because  its  globules  are  straii\pd,  as  it 
were,  and,  in  a manner,  lost  in  a colourless  serum,  which  serves 
them  as  a vehicle. 

It  is,  in  fact,  necessary,  that  bodies  should  be  of  a certain 
bulk,  to  reflect  the  rays  of  light  at  an  angle  sufficiently  obtuse, 
that  the  eye  may  discover  their  colour.  We  know,  that  grains 
of  sand  reduced  to  a very  fine  dust,  appear  colourless  when 
examined  separately,  and  are  seen  to  possess  colour  only  when 
in  a state  of  aggregation;  further,  very  thin  laminae  of  a horny 
substance,  appear  transparent,  though  the  part  from  which  they 
have  been  detached  be  of  a red  or  blue  colour.  But  if  several 
of  these  transparent  laminae  be  laid  on  one  another,  the  red 
colour  becomes  darker,  in  proportion  as  a greater  number  are 
brought  together. 

Let  irritation,  from  whatever  cause,  determine  the  blood  to 
flow  into  the  serous  capillary  vessels,  in  greater  quantity,  and 
with  more  force,  these  vessels  will  become  apparent,  the  organs 
in  whose  structure  they  circulate,  will  acquire  a red  colour,  more 
or  less  deep;  thus  the  conjunctiva,  the  pleura,  the  peritoneum,  the 

* The  arterial  divisions  which  may  be  discerned  by  the  aid  of  anatomy,  do 
not  exceed  eighteen  or  twenty:  nevertheless,  they  divide  still  further,  when 
they  are  become  so  minute  as  not  to  be  discernible  with  the  help  of  the  most 
powerful  microscope. 


ON  THE  CIRCULATION. 


200 

cartilages,  the  ligaments,  &c.  which  naturally  are  whitish  qr 
transparent,  become  red,  when  affected  with  inflammation, 
whether  from  the  increased  impetus  of  the  circulation,  which 
forces  and  accumulates  into  the  capillary  vessels  a greater  num- 
ber of  red  globules,  or  that  the  sensibility  of  these  small  vessels 
is  impaired  by  inflammation,  so  that  they  admit  globules  which 
they  formerly  rejected. 

Some  capillary  vessels  transmit  blood,  at  all  times,  and  uni- 
formly exhibit  a red  colour;  this  is  the  case  with  the  capillary 
vessels  of  the  spleen,  of  the  corpora  cavernosa  of  the  penis,  of 
the  bulb  and  corpus  spongiosum  of  the  urethra;  the  same  applies 
to  the  capillaries  of  the  muscles,  of  the  mucous  membranes; 
there  are,  however,  very  few  of  those  organs,  in  which  the  whole 
portion  of  the  capillary  tube,  between  the  termination  of  the 
artery  and  the  origin  of  the  vein,  is  filled  with  red  blood.  There 
is,  almost  always,  a division  in  the  tortuous  line  described  by 
the  capittary,  and  within  this  space  the  blood  cannot  be  detected 
of  its  usual  colour. 

The  number  of  the  capillary  vessels,  as  well  as  that  of  the 
arteries,  to  which  the  former  are  as  auxiliaries,  is  much  more 
considerable  in  the  secretory  organs,  than  in  those  in  which  life 
carries  on  only  the  process  of  nutrition.  It  is  on  that  account, 
that  the  bones,  the  tendons,  the  ligaments,  the  cartilages,  con- 
tain so  much  smaller  a quantity  of  blood,  than  the  mucous  and 
serous  menribranes,  and  the  skin.  The  capillary  vessels  are, 
however,  very  numerous,  in  the  muscles  which  owe  that  colour 
to  the  great  quantity  of  blood  they  contain;  but,  as  we  shall  point 
out,  when  we  come  to  speak  of  motion,  this  fluid  appears  to 
form  an  essential  element  in  muscular  contraction;  it  is,  there- 
fore, not  to  be  wondered,  that  these  organs  should  have  a greater 
number  of  capillary  vessels  sent  to  them:  since  these  vessels  do 
not  supply  them  m*erely  with  molecules  to  carry  on  nutrition  and 
to  repair  the  waste  of  the  part,  but  impart  to  them  the  principle 
of  their  frequent  contraction:  the  quantity  of  them  is  so  consi- 
derable, in  all  these  parts,  employed  in  the  twofold  oflices  of 
nutrition  and  secretion,  that  Ruysch  penetrated,  with  his  injec- 
tions, the  whole  thickness  of  their  substance,  to  such  a degree, 
that  the  organs  which  he  had  prepared  were  only  a wonderful 
and  inextricable  network  of  capillary  vessels  extremely  minute. 


ON  THE  CIRCULATION, 


201 


On  these  anatomical  preparations,  made  with  an  art  hitherto 
unrivalled,  Ruysch  grounded  his  hypothesis  relative  to  the  inti- 
mate structure  of  the  body,  in  which,  he  imagined,  all  was  capil- 
lary tubes;  a hypothesis  which  has  obtained  the  most  favourable 
reception,  and  has  reigned,  during  more  than  a century,  in  the 
schools.  It  is  enough  to  reflect  a moment  on  their  uses,  to  con- 
ceive that  the  number  of  them  must  be  really  prodigious.  As 
long  as  the  blood  is  enclosed  within  the  arteries,  and  flows 
under  the  control  of  the  heart,  it  fulfils  no  purpose  either  of 
nutrition  or  secretion.  To  make  it  subservient  to  these  great 
functions,  it  must  be  diffused  through  the  very  tissue  of  the  or- 
gans, by  means  of  the  capillary  divisions;  these  little  vessels 
exist  then,  in  every  part,  where  any  organized  molecules  are 
found  united;  since  the  particle  formed  by  their  assemblage, 
must,  at  least,  find,  in  the  juices  which  they  bring  to  it,  the 
materials  of  its  reparation.  Entering,  in  greater  or  less  propor- 
tion, into  the  organization  of  all  the  tissues,  the  capillaries  re- 
ceive certain  modifications  from  the  organs  of  which  they  are  an 
integral  part:  modifications  which  enable  them  to  deposit  the 
serous  part  of  the  blood  on  the  surface  of  the  serous  membranes, 
admit  the  transudation  of  the  fat  into  the  cells  of  the  cellular 
tissue,  furnish  the  urine  to  the  kidneys,  and  the  liver  with  the 
materials  of  the  bile:  in  a word,  suffer  to  escape,  through  the 
porosities  with  which  the  parietes  are  pierced,  the  principles 
which  the  blood  has  to  furnish  to  every  organ. 

It  is  by  these  lateral  porosities,  and  not  by  extremities  open 
on  all  the  surfaces,  and  in  all  the  points  of  the  organs,  that  the 
capillaries  transpire,  in  some  sort,  the  elements  of  nutrition,  and 
of  the  various  secretions.  Mascagni  was  aware,  that  Nature, 
skilful  in  deducing  many  effects  from  few  causes,  has  not  de- 
viated, in  the  construction  of  the  system  of  circulation,  from  the 
invariable  laws  of  her  ordinary  simplicity:  but  the  lateral  pores 
of  the  capillaries,  which  are  sufficient  for  the  exolanation  of  all 
the  phenomena  ascribed  to  the  exhaling  mouths  of  the  arteries, 
and  tothepretended  continuity  of  these  vessels  with  the  excretory 
ducts  of  the  organs,  &c.  are  not  openings  like  the  pores  com- 
mon to  all  matter;  each  of  them  may  be  considered  as  an  orifice, 
sensible,  and,  especially,  contractile,  of  differing  size,  according 
to  the  state  of  the  strength  or  of  the  vital  powers.  The  size  then 

2 C 


ON  THE  CIRCULATION. 


202 

of  these  capillary  pores  is  subject  to  frequent  variations;  anJ 
this  is  the  explanation  given  of  the  formation  of  scorbutic 
ecchymoses,  of  petechise,  and  of  passive  or  relaxed  hemorrhages. 
In  all  these  affections,  contractility  being  really  diminished,  the 
pores  of  the  capillaries  enlarge,  and  suffer  the  red  blood  to  trans- 
ude through  their  relaxed  mouths.  This  phenomenon  takes 
place,  not  only  under  the  skin  and  on  the  various  mucous  sur- 
faces, it  is  observed  also  in  the  very  tissue  of  the  organs.  It  is 
thus,  that  I have  often  seen,  on  opening  the  body  of  those  that 
had  died  of  scurvy,  in  its  last  stage,  the  muscles  of  the  leg  filled 
with  blood.  This  sort  of  interior  hemorrhage,  converts  the  mus- 
cles into  a kind  of  pulp;  and  the  extravasated  blood  itself  under- 
goes a beginning  of  decomposition.  The  bones  themselves  are 
liable-to  these  scorbutic  bloody  infiltrations.  I had  an  opportu- 
nity of  ascertaining  this  in  the  hospital  of  St.  Louis,  at  the  same 
time  that  I learnt  the  difficulty  of  procuring  a durable  skeleton 
from  such  bodies.  The  greatest  number  die  in  a very  advanced 
stage  of  the  disease,  and  the  bones  dissolve  in  maceration,  or 
rot  in  a very  little  time. 

The  capillary  vessels,  whether  the  blood  flow  through  them 
red,  or  colourless,  are  not  a system  of  vessels  distinct  from  that 
of  the  arteries,  and  from  that  of  the  veins;  they  belong  essen- 
tially to  these  two  orders  of  vessels.  Those  which,  ramifying  in 
the  tissue  of  the  skin,  or  of  the  serous  membranes,  suffer  the 
serum  of  the  blood  to  transude,  are  not  more  entitled  to  the 
name  of  exhalant  system,  which  some  authors  have  given  them. 
To  consider  as  distinct  and  insulated  systems,  separate  parts  of 
a system  of  organs,  is  to  encumber  science  with  a crowd  of  divi- 
sions, as  false  as  they  are  useless. 

LXI.  The  sanguineous  capillaries  anastomose,  and  form,  like 
the  lymphatic  capillaries,  a net  work  that  envelops  all  the  organs. 
Their  frequent  communications  do  not  allow  obstructions  to 
take  place  and  to  produce  inflammation,  as  Boerhaave  thought, 
and  as  was  long  taught  on  the  authority  of  that  celebrated  phy- 
sician. Haller,  Spallanzani,  all  the  microscopic  observers,  have 
perceived  threads  of  blood  flowing  in  the  capillaries,  offering 
themselves  at  the  various  inosculations  of  these  vessels,  and 
have  seen  them  flow  back,  when  they  were  not  admitted,  to 
seek  other  easier  entrances. 


ON  THE  CIRCULATION. 


203 


I will  not  collect,  in  this  place,  superfluous  arguments  against 
the  theory  of  the  Leyden  professor,  rejected  at  its  birth  by  the 
physicians  of  Montpellier,  absolutely  refuted,  and  now  univer- 
sally given  up.  Irritation  alone  keeps  the  blood  in  the  inflamed 
part;  for  when  death,  which  puts  an  end  to  all  irritations,  and 
relaxes  all  spasms  (mors  spasmos^  solvit,  Hipp.);  when,  I say, 
death  comes  on,  all  slight  inflammations  are  dissipated,  and 
whenever  they  have  not  been  sufficiently  intense  to  induce  tran- 
sudation of  the  blood  through  the  parietes  of  the  capillaries  into 
the  areolcs  of  the  organic  tissues,  the  blood  flows  back  into  the 
large  vessels,  and  there  is  no  trace  of  it  left.  It  is  thus  that  ery- 
sipelas of  the  skin  disappears,  that  the  pleura  preserves  its  trans- 
parency, in  individuals  affected,  before  death,  with  sharp  pains 
in  the  side.  If  to  this  we  add  our  ignorance  on  the  real  organi- 
zation of  the  nervous  system,  on  the  conditions  absolutely  re- 
quired of  the  brain  and  nerves,  for  the  maintenance  of  life,  we 
shall  cease  to  be  surprized,  that  the  opening  of  bodies  has 
taught  us  no  more  on  the  real  seat  of  disease,  and  we  shall  con- 
fess with  Morgagni,  who  however  employed,  with  great  success, 
this  means  of  improving  the  art  of  healing,  that  there  are  num- 
berless diseases,  of  which,  after  death,  no  trace  is  left,  and  for 
the  fatal  termination  of  which  we  are  unable  to  account. 

Contractility  and  sensibility  exist,  in  a much  higher  degree, 
in  the  capillary  and  serous  vessels,  than  in  the  veins  and  arteries. 
Life  must  needs  be  more  active  in  the  former,  for  the  motion 
given  to  the  blood  by  the  contractions  of  the  heart  being  ex- 
hausted, this  fluid,  no  longer  in  the  sphere  of  action  of  that 
organ,  can  circulate  but  from  the  influence  of  the  action  of  the 
vessels  themselves. 

The  termination  of  the  arteries  into  veins,  is  the  only  well 
ascertained  termination  of  those  vessels;  it  may  be  seen  by  the 
help  of  the  microscope,  in  cold-blooded  animals,  in  frogs  and  sa- 
lamanders. In  some  fish,  we  may,  even  with  the  naked  eye,  ob- 
serve frequent  and  considerable  inosculations  between  the  arte- 
ries and  veins.  In  man,  however,  and  in  other  warm-blooded 
animals,  these  communications  take  place  only  at  the  extremi- 
ties of  the  two  systems  of  vessels.  In  this  case,  the  arteries  ter- 
minate, sometimes,  in  capillary  vessels  carrying  serous  fluid, 
such  are  the  vessels  of  the  sclerotic  coat;  these  vessels  become 


204 


ON  THE  CIRCULATION. 


small  veins  whose  caliber  gradually  increases,  until  they  admit 
red  globules  in  sufficient  number  to  reflect  that  colour.  At  other 
times,  the  artery  and  vein  are  continuous,  without  the  interven- 
tion of  that  extremely  minute  subdivision;  the  red  blood  then 
passes  readily  and  immediately  from  the  artery  into  the  vein. 

It  will  be  shown,  in  speaking  of  secretions,  that  the  continua- 
tion of  the  arteries  into  the  excretory  ducts  of  the  conglomerate 
glands,  and  their  termination  in  exhaling  orifices,  cannot  be  ad- 
mitted; and  that  the  presence  of  small  pores,  in  the  sides  of  the 
minute  arteries  and  veins,  would  afford  an  explanation  of  the 
phenomena  on  which  the  belief  of  this  termination  of  the  arte- 
ries rests.  There  exists  no  parenchyma,  no  spungy  tissue,  be- 
tween the  extremities  of  the  arteries  and  the  origin  of  the  veins, 
with,  perhaps,  the  exception  of  the  substance  of  the  cavernous 
bodies  of  the  penis  and  of  the  clitoris,  of  the  bulb  and  spungy 
part  of  the  urethra,  the  retiform  plexus,  which  surrounds  the  ori- 
fice of  the  vagina,  and  perhaps  also  the  tissue  of  the  spleen, 
though  the  experiments  of  anatomists  (Mascagni  and  Lobstein) 
seem  to  prove,  that  in  these  organs,  the  arteries  and  veins  are 
immediately  continuous. 

LXII.  Of  the  action  of  the  veins.  These  vessels,  whose  func- 
tion it  is  to  carry  back  to  the  heart,  the  blood  which  the  arte- 
ries have  sent  to  all  the  organs,  are  much  more  numerous  than 
the  arteries  themselves.  It  is  observed,  in  fact,  that  arteries  of  a 
middle  size,  as  those  of  the  leg  and  fore-arm,  have  each  two  cor- 
responding veins,  whose  caliber  at  least  equals  theirs,  and  that 
there  is  besides,  a set  of  superficial  veins,  lying  between  the 
skin  which  covers  the  limbs  and  the  aponeuroses  which  envelop 
the  muscles;  these  have  no  corresponding  arteries.  The  space 
which  the  venous  blood  occupies  is,  therefore,  much  greater 
than  that  taken  up  by  the  blood  in  the  arteries.  Hence  also,  it  is 
estimated,  that  of  twenty-eight  or  thirty  pounds  of  this  fluid, 
making  about  a fifth  part  of  the  whole  weight  of  the  body  in  an 
adult  man,  nine  parts  are  present  in  the  veins,  and  only  four  in 
the  arteries.  In  this  calculation,  one  should  consider  as  arterial, 
the  blood  contained  in  the  pulmonary  veins  and  in  the  left  cavi- 
ties of  the  heart,  while  that  which  fills  the  cavities  in  the  right 
side  of  the  heart  and  the  pulmonary  artery,  is  truly  venous,  and 
has  every  character  of  such  blood. 


ON  THE  CIRCULATION. 


205 

Although  the  veins  generally  accompany  the  arteries,  and  are 
united  to  them  by  a common  sheath  of  cellular  membrane,  this 
disposition  of  parts  is  not  without  exceptions.  The  veins  which 
bring  back  the  blood  from  the  liver,  do  not,  in  any  respect,  fol- 
low the  course  of  the  branches  of  the  hepatic  artery;  the  sinuses 
of  the  brain  are  very  different,  in  their  arrangement,  from  the 
cerebral  arteries;  the  veins  of  the  bones,  which  are  particularly 
numerous,  and  of  a much  greater  caliber  than  the  arteries  of  the 
same  parts,  from  the  slow  circulation  of  the  blood  along  them, 
do  not  generally  follow  the  direction  of  the  arteries,  and  arise 
singly  from  the  substance  of  the  bone,  with  the  exception  of 
those  in  the  middle  canal,  and  which  pass  through  the  nutritious 
foramen  of  the  bone.  The  veins  are  not  only  more  numerous 
than  the  arteries,  but  they  are  likewise  more  capacious,  and  di- 
late more  readily:  this  structure  was  necessary,  on  account  of 
the  slowness  with  which  the  blood  circulates,  and  of  the  readi- 
ness with  which  it  stagnates,  when  the  slightest  obstacle  impedes 
its  circulation.*  The  force  which  carries  on  the  circulation  of 
the  blood,  along  the  arteries,  is  so  great,  that  Nature  seems  not 
to  have  availed  herself  of  the  mechanical  advantages  which 
might  have  facilitated  its  flow.  On  the  other  hand,  the  power 
which  determines  the  progression  of  the  venous  blood  is  sofej- 
ble,  that  she  has  sedulously  removed  every  obstacle  which 
might  have  impeded  its  course.  And  as  the  relation  of  the  mi- 
nute to  the  larger  branches,  and  of  these  to  the  trunk,  is  the  same 
as  in  the  arteries,  two  branches  unite  to  form  a vein  of  greater 
caliber  than  each  separate  vessel,  but  smaller  than  the  two  taken 
together,  the  blood  flows  along  a space  which  becomes  narrower, 
the  nearer  it  approaches  the  heart;  the  rapidity  of  its  course, 
must,  therefore,  be  progressively  increased. 

The  veins  are  almost  straight  in  their  course;  at  least,  they 
are  much  less  tortuous  than  the  arteries.  The  force  which 

* The  arteries  contain,  at  all  times,  nearly  the  same  quantity  of  blood.  The 
veins  are  always  the  seat  of  plethora,  because  the  blood  stagnates  in  them  more 
readily;  and  this  condition  brings  on  inflammatory  fever  (consisting  merely  in 
an  increased  action  of  the  vascular  system,  as  is  expressed  by  the  term  an- 
gnotenique  applied  to  it  hy  Professor  Find)  only  when  the  venous  congestion 
becoming  excessive,  the  blood  passes  with  difficulty  from  the  arteries  into  the 
veins.  The  heart  and  the  arteries  then  struggle,  with  considerable  effort,  to 
rid  themselves  of  the  fluid  which  oppresses  them,  &c. 


206 


ON  THE  CIRCULATION. 


makes  the  blood  flow  along  them,  is  consequently  not  taken  up 
in  straightening  these  curves;  the  anastomoses  are,  likewise, 
more  frequent,  and  as  the  flow  of  the  blood  might  have  been  in- 
tercepted in  the  deep-seated  veins  of  the  limbs,  when  the  mus- 
cles, among  which  these  vessels  lie,  during  contraction,  compress 
them  by  their  enlargement  and  induration,  they  communicate 
freely  with  the  superficial  veins,  towards  which  the  blood  is  car- 
ried, and  flows  the  more  readily,  as  they  are  not  liable  to  be 
compressed.  It  is  observed,  and  is  to  be  accounted  for  on  the 
same  principle,  that  the  superficial  veins  are  very  large  and  dis- 
tinct among  the  lower  orders  who  are  employed  in  laborious  oc- 
cupations, requiring  an  almost  continual  exertion  of  their  limbs. 
Lastly,  the  internal  part  of  the  veins,  like  that  of  the  lymphatics, 
is  furnished  with  valvular  folds,  formed  by  the  duplicature  of 
their  epidermoid  coat.  These  valves,  which  are  seldom  single, 
and  almost  always  in  pairs,  are  not  found  in  the  minute  veins, 
nor  in  the  great  trunks,  nor  in  the  veins  which  bring  back  the 
blood  from  the  viscera  in  the  great  cavities. 

These  valves,  in  falling,  close  completely  the  canal  of  the  ves- 
sel, destroy  the  continuity  of  the  column  of  blood  returning  to 
the  heart,  divide  it  into  smaller  columns,  as  numerous  as  the  in* 
tervals  between  the  valves,  and  the  height  of  which  is  determin- 
ed by  the  distance  between  these  folds.  So  that  the  power 
which  carries  onward  the  venous  blood,  and  which  would  be 
incapable  of  propelling  the  whole  mass,  acts  advantageously  on 
each  of  the  small  portions  into  which  it  is  divided. 

LXIII.  It  has  been  thought,  that  the  principal  cause  which 
makes  the  blood  flow  into  the  veins,  is  the  combined  action  of 
the  heart  and  arteries;  but  the  impulse  from  those  organs  is  lost 
in  the  system  of  capillary  vessels,  and  does  not  extend  to  the 
veins.  The  specific  action  of  their  own  parietes,  aided  by 
auxiliary  means,  such  as  the  motion  of  the  neighbouring  arteries, 
is  sufficient  to  carry  the  blood  on  to  the  heart.* 

* In  the  process  of  returning  the  blood  to  the  heart,  two  causes  are  princi. 
pally  engaged,  the  most  efficient  of  which,  is  undoubtedly  the  contractile  poner 
of  the  'veins  themselves.  We  are  aware  that  this  property  is  denied  to  them  by 
many  who  have  speculated  on  the  subject.  It  is  however  shown  by  Haller  that 
the  vena  cava,  at  least,  is  muscular,  and  Verschuyr  and  other  respectable  phy. 
siologists,  have  detected  the  same  structure  in  the  more  minute  veins.  There 
is  one  act  which  we  think  ought  alone  to  convince  us  of  the  contractility  of 


ON  THE  CIRCULATION. 


207 

These  parietes,  which  are  much  thinner  than  those  of  the  ar- 
teries,  are  contained,  like  theirs,  in  a sheath  common  to  all  the 
vessels.  Three  coats,  likewise,  enter  into  their  structure;  the 
middle  or  fibrous  coat  is  not  very  distinct,  and  consists  merely 
of  a few  longitudinal  reddish  fibres,  which  can  be  distinguished 
only  in  the  larger  veins,  near  the  heart.  In  some  of  the  larger 
quadrupeds,  as  in  the  ox,  these  fibres  form  distinct  fasciculi,  and 
their  muscularity  is  much  more  manifest. 

The  internal  coat,  which  is  more  extensible  than  that  of  the 
arteries  and  equally  thin,  adheres  more  closely  to  the  other 
coats.  The  cellular  coat,  which  connects  it  to  the  middle  one,  Is 
less  abundant,  hence  phosphate  of  lime  i-s  seldom  deposited  into 
it,  as  happens  to  the  arteries  which  frequently  become  ossified, 
as  we  advance  in  years.  This  internal  coat  is  merely  a continua- 
tion of  that  which  lines  the  cavities  of  the  heart;  and  as  the  ori- 
gin of  the  inner  coat  of  the  arteries  is  the  same,  there  exists  a 
non-interrupted  continuity  in  the  membrane  which  lines  all  the 
eanals  of  the  circulation.  The  inner  coat  forms  the  only  essen- 
tial part  of  the  venous  system;  it  alone  constitutes  the  veins 
within  the  bones,  the  sinuses  of  the  dura  mater,  the  hepatic 
veins,  in  a word,  all  the  veins  which  are  so  firmly  attached  ex- 
ternally to  the  neighbouring  parts,  that  the  blood  flows  along 
them,  as  along  inert  tubes,  their  parietes  being,  almost  complete- 
ly, incapable  of  contracting. 

The  veins,  in  their  passage  through  muscles,  are,  like  the  ar- 
teries, guarded  by  aponeurotic  rings,  than  which  none  is  more 
remarkable  than  that  which  belongs  to  the  aperture  in  the  dia- 
phragm, which  transmits  the  ascending  cava  from  the  abdomen 
into  the  thorax.  This  vessel  is,  therefore,  not  compressed  by  the 
contraction  of  that  muscle  in  inspiration. 

LX IV.  As  the  inferior  cava  passes  through  the  lower  edge 
of  the  liver,  whether  along  a deep  fissure,  or  in  a real  canal  in  the 

these  vessels,  which  is,  that  they  always  adapt  themselves  to  the  quantity  of 
blood  they  contain. 

Co-operating’  with  the  above  cause  is  the  action  of  the  muscles,  as  may  be 
illustrated  by  the  familiar  example  of  venaesection.  When  in  this  case  the  blood 
issues  languidly  from  the  orifice  made  in  the  vein,  it  is  known,  that  nothing  pro- 
motes its  flow  so  effectually  as  pressing  something  hard  in  the  hand.  This  ope- 
rates simply  by  bringing  into  action  the  muscles  ofthe  fore-arm  and  humerus, 
thereby  producing  considerable  compression  of  the  veins. — Eo. 


208 


ON  THE  CIRCULATION. 


parenchymatous  substance  of  that  viscus,  the  course  of  the 
blood  must  be  impeded,  when,  from  congestion  of  the  paren- 
chyma, the  vessel  is,  in  some  sort,  strangulated. 

Obstruction  of  the  liver,  which  is  of  such  frequent  occur- 
rence, would  be  attended  with  fatal  consequences,  by  prevent- 
ing the  return  of  the  blood  from  the  inferior  parts,  along  the 
ascending  cava,  if  this  great  venous  trunk  did  not  keep  up,  by 
means  of  the  vena  azygos,  an  open  and  free  communication  with 
the  descending  or  superior  cava.  The  use  of  this  anastomosis  of 
the  two  great  veins  is,  evidently,  to  facilitate  the  passage  of  the 
blood  from  the  one  of  these  vessels  into  the  other,  when  either, 
especially  the  lower,  does  not  readily  evacuate  its  contents  into 
the  right  auricle.  On  this  account,  the  vena  azygos  is  capable  of 
considerable  dilatation,  and  is  entirely  without  valves.  In  the 
body  of  a man  opened  this  day  in  my  presence,  and  whose  liver 
was  twice  as  large  as  in  health,  I observed,  that  the  vena  azygos, 
which  was  distended  with  blood,  was  of  the  size  of  the  little  fin- 
ger; the  termination  downward  of  this  vessel,  in  the  right  renal 
vein,  and  above  in  the  superior  cava,  were  most  distinct,  and  by- 
compressing  it  from  above  downward,  or  from  below  upward, 
the  blood  flowed  into  the  one  or  other  of  these  vessels. 

As  the  causes  which  determine  the  circulation  of  the  venous 
blood,  communicate  to  it  an  impulse  which  is  far  from  rapid,  and 
as  this  fluid  meets  with  only  trifling  obstacles,  and  such  as  are 
easily  overcome,  the  pressure  against  the  parietes  of  the  veins  is 
very  inconsiderable,  and  these  vessels  do  not  pulsate,  as  the  ar- 
teries, There  is  observed,  however,  near  the  heart,  an  undula- 
tory  motion  which  the  blood  communicates  to  the  parietes  of  the 
vessels.  These  kinds  of  alternate  pulsations  depend  on  the  ra- 
pidity with  which  the  blood,  whose  course  is  progressively  ac- 
celerated, flows  towards  the  heart,  and  on  the  reflux  of  the 
blood,  during  the  contraction  of  the  right  auricle.  The  contrac- 
tion of  this  cavity  forces  back  the  blood  into  the  veins  which 
open  into  it;  this  retrograde  course  is  manifest  in  the  superior 
cava,  and  is  the  more  readily  occasioned  as  the  orifice  of  this 
vein  is  not  furnished  with  any  valve  that  might  prevent  it.  It 
does  not,  however,  extend  very  far  towards  the  brain,  the  blood 
having  to  ascend  against  its  own  weight,  and  the  jugulars  ad- 
mitting of  considerable  dilatation.  This  regurgitation  is  still 


ON  THE  CIRCULATION. 


209 

more  marked  in  the  inferior  cava,  the  orifice  of  which  is  but  im- 
perfectly closed  by  the  valve  of  Eustachius;  it  is  felt  in, the  ab- 
dominal veins,  and  extends  even  to  the  external  iliacs,  according 
to  the  testimony  of  Haller. 

LXV.  The  orifice  of  the  great  coronary  vein  being  exactly 
covered  over  by  its  valve,  the  blood  does  not  return  into  the 
tissue  of  the  heart,  which  being  a contractile  organ,  would  have 
had  its  irritability  impaired  by  the  presence  of  venous  blood.  It 
is  of  consequence  to  observe,  that  this  reflux  never  extends  to 
the  veins  which  bring  back  the  blood  from  the  muscles,  and  that 
it  is  never  felt  in  the  veins  of  the  limbs  which  are  furnished  in* 
ternally  with  valvular  folds.  The  case  is  very  different  between 
our  organs  of  motion  and  these  secretory  glands;  towards  these 
the  blood  required  to  be  sent  back,  so  as  to  be  the  longer  ex- 
posed to  their  action:  venous  blood  diminishes  and  even  de- 
stroys muscular  irritability,  and  is  truly  oppressive,  as  may  be 
ascertained  by  injecting  some,  in  the  arteries  of  a living  animal, 
or  else  by  tying  the  veins,  so  as  to  prevent  its  return,  or  by  ob- 
serving what  happens,  when  the  course  of  the  blood  is  interrupt- 
ed, either  by  applying  firm  ligatures  round  the  limbs,  or  by 
wearing  confined  clothes. 

I am  satisfied,  that  it  was  from  observing  the  oscillatory  un- 
dulations of  the  venous  blood,  in  the  great  vessels,  that  the  an- 
cients were  led  to  the  opinions  they  entertained  on  the  course  of 
the  blood,  which  they  compared  to  the  Euripus,  whose  waves 
are  represented  by  the  poets,  as  uncertain  in  their  course,  and  in 
currents  running  in  contrary  directions. 

The  internal  veins  in  which  this  reflux  is  observed,  show  this 
motion  of  the  blood  most  distinctly  of  any;  their  sides,  which  are 
thin  and  semi-transparent,  not  being  as  in  other  parts,  surround- 
ed by  an  adipose  cellular  tissue.  To  give  a complete  notion  of  the 
doctrine  of  the  ancients,  on  the  subject  of  the  circulation,  it  will 
merely  be  necessary  to  add  to  the  above  idea,  the  opinion  which 
they  entertained,  that  the  ch)de  taken  up  by  the  meseraic  veins, 
was  carried  to  the  liver,  in  which  its  sanguification  was  effected, 
and  lastly,  that  the  arteries  were  filled  with  vital  spirit,  and  con- 
tained only  a few  drops  of  blood  which  passed  through  small 
holes,  which,  Galen  says,  perforate  the  septum  of  the  ventricles. 

The  blood,  however,  continually  urged  on  by  the  columns 

2 D 


ON  THE  CIRCULATION, 


210 

which  follow  each  other  in  succession,  by  the  action  of  the  veins 
whose  parietes  become  gradually  stronger,  and  by  the  compres- 
sion which  these  vessels  experience  from  the  viscera,  during  the 
motions  of  respiration,  reaches  the  heart,  and  enters  the  auricles 
with  the  greater  facility,  as  the  orifices  of  the  cavas  not  being  di- 
rectly opposed  to  each  other,  the  columns  of  blood  which  they 
convey  do  not  meet  and  do  not  oppose  each  other. 

LXVI.  The  blood,  continually  carried  to  all  parts  of  the 
body  by  the  arteries,  returns,  therefore,  to  the  heart,  by  a mo- 
tion which  can  never  be  interrupted,  without  considerable 
danger  of  life.  We  know,  that  the  circulation  is  thus  effected, 
from  the  direction  of  the  valves  of  the  heart,  of  the  arteries  and 
veins;  by  what  happens  when  these  vessels  are  opened,  compress- 
ed or  tied,  or  when  a fluid  is  injected  into  them.  When  an  arte- 
ry is  wounded,  the  blood  comes  from  the  part  of  the  vessel 
nearest  the  heart;  it  comes,  on  the  contrary,  from  towards  the 
extremities,  if  it  is  a vein  that  has  been  opened.  By  compress- 
ing or  tying  an  artery,  the  course  of  the  blood  is  suspended  be- 
low the  ligature,  and  the  vessel  swells  above.  The  veins,  on  the 
contrary,  when  tied  or  compressed,  dilate  below.  Lastly,  when 
an  acid  fluid  is  injected  into  a vein,  the  blood  is  seen  to  coagu- 
late in  the  direction  of  the  heart.  By  the  help  of  the  microscope, 
we  may  see  in  the  semi-transparent  vessels  of  frogs  and  other 
cold-blooded  animals,  the  blood  flowing  from  the  heart  into  the 
arteries,  and  from  these  into  the  veins  which  return  it  to  the 
heart.  It  was  on  the  strength  of  these  convincing  proofs,  that 
William  Harvey  established,  towards  the  middle  of  the  six- 
teenth century,  the  theory  of  the  circulation  of  the  blood.  Its 
mechanism  had  been  rather  guessed  at,  than  understood,  by  se- 
veral authors:  Servetus  and  Cesalpinus  appear  to  have  been  ac- 
quainted with  it;  but  no  one  has  more  clearly  explained  it  than 
the  English  physiologist,  who  is  justly  considered  the  author  of 
that  immortal  discovery. 

LXVII.  The  theory  of  Harvey,  such  as  it  is  laid  down  in  his 
work,  entitled,  De  sanguinis  circuitu,  exercitationes  anatomical 
does  not  appear  to  me  entirely  admissible. — He  considers  the 
heart  as  the  only  agent  which  sets  the  blood  in  motion,  and  does 
not  take  into  account  the  action  of  the  veins  and  arteries,  which 
he  considers  as  completely  inert  tubes,  while  every  thing  tends 


ON  THE  CIRCULATION. 


211 

to  prove  that  the  arteries  and  veins  assist  the  motion  of  the  blood, 
by  an  action  peculiar  to  themselves.  He  admits,  that  the  blood 
flows,  in  every  part  of  the  circulatory  system,  with  an  uniform 
degree  of  speed;  an  opinion  so  manifestly  contradicted  by  rea- 
soning and  experience,  which  proves  that  the  velocity  of  its 
course  diminishes,  the  greater  its  distance  from  the  heart,  from 
the  influence  of  a great  number  of  circumstances,  which  it  would 
be  useless  to  repeat  (LVII.)  This  doctrine  has  yet,  however, 
several  abettors,  and  among  the  moderns,  Spallanzani  has  en- 
deavoured to  support  it,  by  a number  of  experiments  so  contra- 
dictory, that  one  is  surprised  that  so  judicious  a physiologist 
should  have  collected  them  to  establish  a theory  completely  re- 
futed by  several  of  them.  Nothing,  for  example,  contradicts  it 
more  fully,  than  the  continuation  of  the  flow  of  the  blood,  in  the 
vessels  of  frogs  and  salamanders,  after  the  heart  of  these  reptiles 
have  been  torn  out;  there  are  besides,  animals  which  not  pos- 
sessed of  that  central  organ,  have  nevertheless  vessels  along 
which  the  blood  flows,  and  which  contract  and  dilate  by  alter- 
nate motions. 

If  the  mere  force  of  the  heart  propelled  the  blood  to  every 
part,  the  course  of  this  fluid  ought,  at  intervals,  to  be  suspended, 
its  circulation,  at  least,  ought  to  be  slackened,  when  the  ventri- 
cles cease  to  contract;  but  as  the  contraction  of  the  arteries  cor- 
responds to  the  relaxation  of  the  ventricles,  these  two  powers 
whose  action  alternates,  are  continually  employed  in  propelling 
the  blood  along  its  innumerable  channels. 

Besides  the  general  circulation  of  which  the  laws  and  pheno- 
mena have  just  been  mentioned,  each  part  may  be  said  to  have 
its  peculiar  mode  of  circulation,  more  or  less  rapid,  according  to 
the  arrangement  and  structure  of  its  vessels.  Each  of  these  in- 
dividual circulations  forms  a part  of  the  machinery  included  in 
the  great  circle  of  the  general  circulation,  and  in  which  the 
course  of  the  blood  takes  place  in  a different  manner,  may  be  ac- 
celerated or  retarded,  without  affecting  the  general  circulation. 
Thus,  in  whitlow  of  a finger,  the  radial  artery  pulsates  a hundred 
times  in  a minute,  while  on  the  sound  side,  its  beats  are  only  se- 
venty in  number,  and  perfectly  isochronous  with  the  pulsations  of 
the  heart.  In  the  same  manner,  the  blood  of  the  intestines,  which 


ON  THE  CIRCULATION. 


212 

is  destined  to  furnish  the  materials  of  the  bile,  flows  much  more 
slowly  than  that  of  other  parts. 

These  modifications  affecting  the  velocity  of  the  circulatory 
motion  of  the  blood,  account  for  the  difference  of  its  qualities 
in  different  organs;  all  these  differences  form  a^part  of  the  plan 
of  Nature,  and  it  is  not  difficult  to  understand  their  utility. 

LXVIII.  In  what  has  been  said  of  the  circulation,  no  sepa- 
rate mention  has  been  made  of  the  course  of  the  blood  through 
the  lungs,  called  by  authors  the  lesser  or  pulmonary  circulation. 
The  vascular  system  of  the  lungs,  with  the  addition  even  of  the 
cavities  of  the  heart  which  belong  to  it,  does  not  represent  a com- 
plete circle,  it  is  only  a segment,  or  rather  an  arch  of  the  great 
circle  of  the  general  circulation. 

The  blood,  in  going  along  that  great  circle,  meets  with  the  or- 
gans, situated  like  so  man>  points  of  intersection  in  the  course  of 
the  vessels  which  form  that  circle. 

To  render  still  more  simple,  the  idea  which  is  to  be  entertain- 
ed on  the  subject,  one  may  reduce  these  intersections  to  two 
principal  ones;  the  one  corresponding  to  the  lungs,  the  other  to 
the  rest  of  the  body;  the  veins,  the  right  cavities  of  the  heart, 
and  the  pulmonary  artery  with  its  divisions,  forming  one  half  of 
the  circle;  the  pulmonary  veins,  the  left  cavities  of  the  heart,  the 
aorta  with  all  its  branches,  representing  the  other  half.  The  ca- 
pillary vessels  of  the  lungs  form  one  of  the  points  of  intersection, 
and  the  capillaries  of  all  the  other  organs  represent  the  other 
point  of  intersection,  by  uniting  together  the  arteries  and  veins 
of  the  whole  bod}',  in  the  same  manner  as  those  of  the  lungs  es- 
tablish a communication  between  the  veins  and  arteries  of  these 
organs. 

This  division  of  the  system  of  circulation  into  two  parts,  in 
one  of  which  there  circulates  a dark  or  venous  blood,  while  the 
other  contains  red  or  arterial  blood,  is  at  once  more  simple  and 
more  accurate.  As  was  already  stated  in  the  history  of  the  cir- 
culation, its  organs  are,  in  an  especial  manner,  destined  to  the 
mechanical  act  of  conveying  the  fluids:  the  changes,  the  altera- 
tions which  the  blood  undergoes  in  passing  through  the  organs, 
are  eflected,  only  at  the  moment  when  in  penetrating  into  their 
tissue,  it  passes  into  the  capillary  vessels  w'hich  are  distributed 
into  them.  The  columns  of  blood  are  then  suificiently  minute  to 


ON  THE  CIRCULA.TION. 


213 


be  operated  upon  by  the  vital  action;  till  then,  the  columns  of 
blood  are  too  large,  and  resist,  by  their  balk,  if  one  may  so  speak, 
any  decomposition.  It  is,  therefore,  in  the  capillary  vessels,  that 
the  blood  receives  its  essential  principles;  and  to  understand 
how  the  nutritious  lymph  which  is  deposited  by  the  thoracic  duct 
into  the  left  subclavian  vein,  experiences  in  its  course  along  the 
sanguiferous  system,  the  changes  which  are  to  assimilate  it  to 
our  own  substance,  it  is  necessary  to  follow  it,  along  the  venous 
blood  with  which  it  unites,  into  the  heart,  through  the  right  half 
of  which  it  passes  in  its  way  to  the  lungs,  there  to  combine  with 
the  atmospherical  air,  from  which  we  are  perpetually  deriving 
another  aliment  indispensable  to  life;  then  to  examine,  how, 
when  modified  and  conveyed  with  the  red  blood,  from  the 
lungs  to  the  whole  body,  it  serves  to  the  secretions,  and  sup- 
plies nourishment  to  the  whole  body. 

In  considering,  in  this  manner,  the  circulation  of  the  blood, 
with  a reference  to  the  changes  which  it  undergoes  in  the  organs 
through  which  it  passes,  in  describing  that  circle,  we  shall  find, 
that  this  fluid,  already  combined  with  the  lymph  and  chyle, 
parts,  in  the  lungs,  with  some  of  its  principles;  at  the  same  time 
that  it  becomes  impregnated  with  the  vital  portion  of  the  atmos- 
phere, which  suddenly  changes  its  colour  and  other  qualities. 
The  blood  will  then  be  seen  to  flow  into  all  the  parts  which  it 
stimulates,  to  keep  up  their  energy,  to  awaken  their  action  and 
furnish  them  the  materials  of  the  fluids  which  they  secrete,  or 
the  molecules  by  which  they  grow  or  are  repaired;  so  that  in 
supplying  thus  the  different  organs,  the  blood  loses  all  the  quali- 
ties which  it  had  acquired  by  the  union  of  the  chyle  and  of  the 
vital  air,  parts  with  the  principles  to  which  it  owed  its  colour, 
and  again  becomes  dark,  to  be  repaired  anew  by  combining  with 
the  lymph,  and  by  the  absorption  of  the  vital  part  of  the  atmos- 
pherical air;  this  constitutes  the  principal  phenomenon  of  the 
function,  which  will  be  considered  in  the  fourth  chapter. 


214 


CHAPTER  IV. 

OF  RESPIRATION. 

Lxix.  Of  the  different  changes  which  the  blood  undergoes 
in  the  different  organs,  none  are  more  essential  or  more  remarka- 
ble than  those  it  receives  from  the  air,  which,  during  respiration, 
is  alternately  received  into  the  lungs  and  expelled  from  them. 
The  blood  which  -the  veins  convey  to  the  heart,  and  which  the 
right  ventricle  transmits  to  the  lungs,  is  of  a dark  colour,  and 
heavy;  its  temperature  is  only  thirty  degrees  (Reaumur’s  ther- 
mometer); if  laid  by,  it  coagulates  slowly,  and  there  is  separated 
from  it  a cdnsiderable  quantity  of  serum.  The  blood  which  is 
. brought  by  the  pulmonary  veins  to  the  left  side  of  the  heart,  and 
which  is  conveyed  to  all  parts  of  the  body  by  means  of  the 
arteries,  is,  on  the  contrary,  of  a florid  red  colour;  it  is  spumous, 
lighter,  and  warmer  by  two  degrees.  It  likewise  coagulates 
more  readily,  and  contains  a smaller  quantity  of  serum.  All 
these  differences,  which  are  so  easily  distinguished,  depend  on 
the  changes  which  it  has  undergone,  by  being  in  contact  with 
the  atmospherical  air. 

LXX.  Of  the  atmosphere.  The  mass  of  air  which  surrounds 
the  globe,  and  to  which  we  give  the  name  of  atmosphere,  bears 
on  all  bodies  with  a pressure  proportioned  to  their  surface.  That 
of  man*  bears  a weight  of  air  amounting  to  about  thirty-six 
thousand  pounds.  Moreover,  one  of  its  constituent  principles  is 
absolutely  necessary  to  the  keeping  up  of  life,  of  which  it  is  a 
principal  agent. 

The  variations  in  the  weight  of  the  atmosphere  have,  in  gene- 
ral, but  little  influence  on  the  exercise  of  the  functions;  never- 
theless, when  by  ascending  the  tops  of  very  high  mountains, 
man  rises  several  thousand  fathoms  above  the  level  of  the  sea, 
the  very  remarkable  diminution  of  the  weight  of  the  air  pro- 
duces a very  sensible  effect.  Respiration  becomes  laborious  and 

* The  surface  of  the  body  is  estimated  at  fifteen  or  sixteen  square  feet,  in  a 
man  of  middle  size. 


/ 


OP  RESPIKATION. 


215 

panting,  the  pulse  is  quickened,  and  there  is  felt  an  universal 
uneasiness,  joined  to  excessive  weakness,  and  hemorrhages 
come  on;  these  symptoms  are  occasioned  both  by  the  diminish- 
ed pressure  of  the  air,  and  by  the  smaller  quantity  of  oxygen 
contained  in  a rarer  atmosphere.* 

* Several  travellers  whose  reports  on  the  subject  I have  consulted,  agree  in 
representing  the  corporeal,  as  well  as  some  of  the  mental  functions,  to  be  very 
strangely  influenced  by  a rarified  condition  of  the  atmosphere.  But  the  cele- 
brated De  Saussure,  a writer,  who  unites  to  the  profundity  of  philosophical  re- 
search, the  polish  of  literary  refinement,  has  from  personal  experience  de- 
scribed these  affections  with  the  most  precision.  To  his  description  I shall, 
therefore,  principally  adhere  in  the  ensuing  enquiry. 

He  states,  that  at  a certain  height  above  the  level  of  the  sea,  there  uniform- 
ly takes  place  a sudden  and  uncommon  exhaustion  of  the  muscular  power. 
The  natives  of  the  Alps,  who  can  climb  for  hours  at  the  foot  of  the  mountains 
without  being  at  all  wearied,  are  forced  to  stop,  and  take  breath  every  few 
minutes,  when  they  ascend  the  height  of  fourteen  or  fifteen  hundred  toises. 
Those  w’ho  are  less  accustomed  to  the  air  of  the  mountains  are  obliged  to  rest 
much  more  frequently.  So  intolerable,  indeed,  is  the  fatigue  induced  in  this 
situation,  that  the  person  suffering  it,  is  rendered  sometimes  wholly  incapable 
of  motion  If  he  attempt  to  move,  his  legs  sink  under  him,  his  heart  palpitates, 
his  arteries  throb,  his  head  becomes  giddy,  his  eyes  are  dazzled,  and,  to  avoid 
fainting,  he  is  forced  to  sit  down.  Near  the  top  of  Mont  Blanc  our  traveller 
could  not  advance  more  than  a few  steps  without  stopping  to  respire,  and  on 
the  summit  of  it,  though  his  exertions  were  moderate,  he  was  constrained 
frequently  to  desist  altogether  from  them,  and  to  breath  laboriously  to  recruit 
his  strength.*  With  this  excessive  degree  of  fatigue,  accelerated  pulse,  and 
difficult  respiration,  there  is  great  thirst,  sickness  of  stomach,  a loathing  of 
food,  and  an  aversion  to  every  species  of  spirituous  liquor.  But  what  is  very 
extraordinary,  these  affections  are  as  short  in  their  duration,  as  they  are 
violent. 

After  resting  a few  minutes,  the  sense  of  fatigue  is  so  completely  dissipated, 
that  the  person,  in  resuming  his  journey,  feels  such  a renovation,  that  he  is 
persuaded  he  will  be  able  to  prosecute  it  uninterruptedly.  He,  however,  is 
soon  disappointed.  On  moving  a short  distance  only,  his  former  inability  re- 
turns, and  his  progress  is  again  arrested.  An  additional  effect  of  this  state  of 
the  atmosphere,  is  an  almost  irresistible  propensity  to  sleep.  We  are  told,  that 
if  the  attention  of  the  person  be  not  engaged,  and  kept  excited,  he  will,  when 
pausing  to  rest,  often  fall  to  sleep  almost  instantaneously,  though  annoyed  by 
the  wind  or  cold,  the  light  or  heat  of  the  sun,  and  in  the  most  incommodious 

These  effects  are  not  peculiar  to  the  human  species.  The  same  writer  re- 
lates, that  the  mules  which  he  employed  to  carry  his  baggage,  became  sud- 
denly so  weak  and  exhausted  that  they  could  hardly  walk,  even  when  the 
burden  was  removed  from  their  backs.  They  staggered  as  they  moved;  their 
respiration  was  panting  and  difficult,  and  seemingly  attended  with  painful  sen- 
sations of  the  chest,  as  tliey  uttered  plaintive  and  distressing  cries. 


OF  RESPIRATION. 


216 

The  human  body  resists,  without  any  effort,  the  atmospherical 
pressure,  because  it  is  applied,  at  all  times,  and  in  every  direc- 
tion. But  if  a part  of  its  surface  ceases,  for  a moment,  to  be 
under  its  influence,  it  swells,  the  fluids  are  determined  to  it,  in 

and  disagreeable  posture  of  his  body.  This  sleep,  sometimes,  approaches  in 
soundness  nearly  to  lethargy.* 

Nothing  affords  the  least  relief  to  any  of  the  symptoms  enumerated  except 
rest  and  cold  -water.  Cordials  and  spirituous  liquors  are  found  to  aggravate  all 
the  complaints. 

Now,  in  what  manner  are  these  singular  affections  to  be  explained!  We 
believe  with  our  author  that  they  are  in  part  owing  totl>e  diminished  pressure 
of  the  atmosphere,  but  infinitely  more  to  a deficiency  of  oxygen. 

It  is  clearly  ascertained  that  respiration  supports  animal  life, and  alt  its  actions. 
This  process  requires  the  presence  of  two  principles.  These  are  oxygen  and 
combustible  matter.  The  former  is  supplied  chiefly  through  the  medium  of 
the  lungs,  and  the  latter  by  the  stomach.  Of  the  vital  actions,  none  seems  to 
be  more  immediately  dependent  and  strikingly  regulated  by  respiration  than 
the  muscular.  It  is  not,  however,  my  design  to  dwell  on  the  relation  between 
them.  It  is  sufficient  for  my  purpose  to  remark,  that  during  exercise  agreater 
quantity  of  oxygen  is  extracted  from  the  atmosphere  by  tlie  lungs,  and  that 
carbonic  acid  and  water  are  formed,  and  caloric  evolved  in  corresponding 
proportions.  Hence  it  may  be  deduced,  that  during  muscular  exertion,  there 
is  a greater  demand  for  oxygen,  and  a larger  consumption  of  combustible  matter. 
It  also  follows,  if  the  preceding  premises  be  admitted,  as  a legitimate  corollary, 
that  the  same  effect  would  be  produced,  namely,  an  exhaustion  of  the  muscu- 
lar vigour,  by  withholding  the  one  or  the  other  of  these  agents.  Iq  either  case, 
fatigue  will  be  caused,  and  the  body  rendered  incapable  of  muscular  exertion. 
But  the  incapacity  in  the  two  cases  arises  from  different  states  of  the  system, 
and  will  be  distinguished  by  different  appearances,  and  removed  by  different 
methods  of  treatment. 

Limited  exercise  in  an  atmosphere  of  sufficient  density,  slotvly  deprives  the 
body  of  its  proper  quantity  of  com.bustible  matter  until  fatigue  is  finally  in- 
duced. The  body  is  afterwards  gradually  recruited  by  rest  and  food,  or,  di- 
rectly restored  to  momentary  strength  by  the  use  of  spirituous  liquors,  which 
are  pure  combustible  matter  mixed  with  water. 

But  in  the  elevated  regions  of  the  atmosphere  where  there  is  a deficiency  of 
oxygen,  the  fatigue  which  comes  on,  is  of  an  opposite  kind.  It  arises  from  an 
over-proportion  of  combustible  matter,  and  a ‘oiant  of  oxygen.  Here,  of  course,  it  is 
alleviated  by  rest,  and  deep  inspirations,  and  exacerbated  by  exercise  and 
spirituous  liquors.  , It 

* It  may  al.so  be  observed,  that  aeronauts  have  generally  mentioned  drowsi- 
ness as  one  of  the  consequences  produced  by  the  attenuated  atmosphere  of  the 
exalted  regions  which  they  explore  in  their  excursive  flights,  and  some  have 
even  declared  that  they  slept  soundly,  when  at  the  utmost  pitch  of  their  peril- 
ous adventures. 


OF  RESPIRATION. 


217 

considerable  quantity,  the  integuments  become  excessively  dis- 
tended, so  as  to  be  in  danger  of  bursting;  such  are  the  pheno- 
mena which  attend  the  application  of  cupping  glasses. 

It  is  suddenly  induced,  because,  the  pulmonary  system  is  so  contrived  that 
the  body  at  no  instant  receives  more  oxygen  than  what  at  the  instant  it 
requires.* 

It  is  speedily  removed,  because,  by  the  deep  inspirations  the  necessary  quan- 
tity of  oxygen  is  conveyed  into  the  system. 

It  is  accompanied  by  sickness  of  stomach,  and  loathing  of  food,  because,  di- 
gestion, like  exercise,  dernands  a copious  supply  of  oxygen  f 

It  is  attended  by  excessive  thirst,  because,  in  a rare  atmosphere,  there  will,  of 
necessity,  be^  profuse  evaporation  from  the  surface  of  the  body. 

The  pulsations  of  the  heart  are  more  numerous,  because  they  are  performed 
less  vigorously. 

Not  altogether  dissimilar  in  its  nature,  or  origin,  though  milder  in  its  symp- 
toms, and  slower  in  its  occurrence,  is_the  fatigue  occasioned  by  immoderate 
exercise  under  the  ordinary  constitution  of  the  atmosphere.  In  this  case,  we 
observed  an  increased  frequency  of  the  pulse,  and  of  respiration,  &c.  &c.  The 
cure  likewise  is  by  rest.  Cold  water  is  found  more  refreshing  than  spirituous 
liquors. 

There  is  another  phenomenon  connected  with  the  present  subject  which  de- 
serves to  be  noticed.  I allude  to  the  propensity  to  sleep  which  has  already  been 
remarked.  This  too,  can  only  be  explained  by  ascribing  it  to  a deficiency  of 
oxygen. 

Sleep  is  a suspension  to  all  or  a majority  of  the  operations  of  the  mind.  We 
have  not,  it  is  true,  in  our  possession  any  direct  evidence  to  prove  that  the 
efforts  of  the  intellect,  like  those  of  the  body,  exact  a fixed  and  determinate 
quantity  of  oxygen.  We  had,  indeed,  the  promise  of  some  experiments  to 
ascertain  it  by  Lavoisier,  in  an  essay,  where  after  indicating  the  expenditure 
of  vital  air  by  muscular  exercise,  he  undertakes  to  show  b}'  calculaiini,  “tlie 
quantity  of  mechanical  labour  exerted  by  the  philosopher  who  reflects,  by  the 
man  of  letters  who  v<rites, or  the  musician  who  composes!"  These  operations,  he 
adds,  though  intellectual,  have  a certain  dependance  on  the  physical  and  ma- 

* We  are  instructed  by  experiments  that  animals  placed  in  a vessel  filled 
with  oxygen,  and  respiring  the  gas  in  a state  of  purity,  do  not  consume  more 
of  it  than  when  combined  with  an  irrespirable  gas.  Thus  it  takes  an  animal 
nearly  four  times  as  long  to  consume  the  same  quantity  of  oxygen  as  atmos- ’ 
pheric  air. 

f There  are  many  facts  to  prove  that  oxygen  is  a principal  agent  in  diges- 
tion and  assimilation.  The  quantity  employed  in  these  processes  seems,  in 
some  degree,  to  be  regulated  by  the  kind  of  food  used.  An  animal  diet  con- 
sumes more  than  a vegetable  one.  Mr.  Spalding  found  that  when  he  lived 
upon  animal  food,  and  drank  spirituous  liquors,  he  expended  the  oxygenous 
portion  of  the  atmosphere  in  his  diving  bell,  in  a much  shorter  time  than  when 
he  subsisted  on  vegetable  matter  and  water.  Dr.  Beddoes  has  also  furnished 
some  curious  facts  which  go  to  establish  the  same  conclusion, 

2 E 


OF  RESPIRATION. 


218 

The  pressure  of  the  air,  on  the  surface  of  the  globe,  is  neces- 
sary to  the  existence  of  bodies  in  the  condition  in  which  we  see 
thena.  Several  very  volatile  fluids,  as  alcohol  and  ether,  would 
become  gaseous,  under  a less  pressure  of  the  atmosphere;  water 
would  boil,  under  eighty  degrees  of  temperature  (Reaumur’s 
scale);  solid  bodies  themselves  might  become  fluid.  In  a word, 
a considerable  diminution  in  the  weight  of  the  atmosphere  would 
have  absolutely  the  same  effect,  as  raising  its  temperature  to  a 
very  great  height)  which,  changing  the  face  of  the  universe, 
would  convert  all  liquids  into  elastic  fluids,  and  would,  doubt- 
less, melt  all  solid  bodies. 

The  variations  in  the  weight  of  the  atmosphere,  distinguish- 
able by  the  barometer,  are  of  very  little  importance  to  the  phy- 
siologist, and  I might  even  add  to  the  physician,  notwithstanding 
the  minute  attention  with  which  some  writers  note  the  state  of 
the  barometer,  of  the  thermometer  and  hygrometer,  and  of  the 
electrical  state  of  the  atmosphere,  in  giving  an  account  of  a dis- 
ease or  of  an  experiment,  on  which  the  above  circumstances 
have  no  apparent  or  certain  influence.  The  atmosphere,  like 
every  other  fluid,  has  a perpetual  tendency  to  a state  of  equili- 
brium; hence  the  rush  of  air  into  the  lungs,  or  into  other  situa- 

terial  part  of  man,  which  renders  them  susceptible  of  comparison  with  the 
labours  of  the  mechanic. 

Wliether  these  views  be  as  just  as  they  are  brilliant,  I shall  not  pretend  to 
decide.  But,  thou.i^h  we  may  never  be  competent  to  determine  with  much 
accuracy  the  quantity  of  oxygen  consumed  by  the  operations  of  the  mind,  yet, 
that  it  is  essentially  necessary  to  the  exertion  of  the  intellectual  faculties  is 
sufficiently  probable. 

With  respect  to  the  influence  of  a subtraction  of  oxygen  in  the  production  of 
sleep,  a few  facts  will  be  sufficient  to  attest  it. 

In  the  first  place,  we  know,  that  the  primary  operation  of  all  the  irrespirable 
gases,  and  these  contain  no  oxygen,  is  productive  of  heaviness  and  sleep. 

Sleep  is  apt,  moreover,  to  occur  during  the  process  of  digestion,  when  the 
oxygen  of  the  system  is  employed,  in  a considerable  degree,  in  the  assimilation 
of  aliment,  and  the  elaboration  of  chyle;  or,  if  the  disposition  to  sleep  be  coun- 
teracted, the  senses,  at  least,  become  more  dull,  and  the  understanding  less 
acute  and  energetic. 

The  production  of  sleep  is  favoured  too,  as  has  been  proved,  by  external 
warmth,  which  lessens  the  supply  of  oxygen. 

It  is  from  the  combination  of  these  causes,  that  among  the  inhabitants  of 
hot  climates,  the  custom  of  sleeping  during  the  day,  and  especially  after  eating, 
universally  prevails.  We  must  acknowledge  that  the  outline  of  tliis  theorj’  was 
derived  from  the  Lectures  of  Mr.  Allen,  of  Edinburgh,  on  Physiologj-. — Ed. 


OF  RESPIRATION. 


219 

tions  in  v/hich  its  quantity  is  diminished,  by  the  combinations 
which  it  forms,  or  by  the  effects  of  heat,  which  renders  it  lighter 
by  rarefaction:  the  same  principle  explains  the  formation  of  the 
trade  and  other  winds. 

The  atmospherical  air  combines  with  water  and  dissolves  it, 
as  the  latter  dissolves  saline  substances.  In  this  consists  the 
process  of  evaporation.  The  air  becomes  saturated  with  water 
in  the  same  manner  as  water  becomes  saturated  with  salt,  to 
such  a degree  as  to  be  incapable  of  holding  a greater  quantity 
in  solution.  As  its  temperature  rises  its  solvent  power  in- 
creases, and  the  latter  diminishes  as  it  grows  cold;  variations 
of  temperature  produce  the  same  effect  on  solutions  of  salts  in 
liquids.  The  formation  of  all  the  aqueous  meteors,  depends  on 
the  different  conditions  of  the  solvent  powers  of  the  atmosphere; 
when  considerable,  the  atmosphere  is  warm  and  dry  and  the  air 
serene;  clouds  form  when  it  is  saturated;  dews,  fogs,  and  rain, 
are  the  consequence  of  a diminution  of  its  solvent  power,  as 
snow  and  hail,  of  a degree  of  cold  which  precipitates  the  fluid. 
The  different  degrees  of  dryness  or  moisture,  marked  by  the 
hygrometer,  only  sensibly  affect  the  human  body,  when  it  has 
been  exposed  for  a considerable  time  to  its  influence. 

Chemically  considered,  the  atmospherical  air,  which  was  long 
regarded  as  a simple  body,  is  composed  of  about  0,27  of  oxygen, 
0,73  of  azote,  and  of  0,01  or  0,02  of  carbonic  acid.  The  propor- 
tions of  oxygen,  according  to  Humboldt,  vary  from  0,23,  to 
0,29;  that  of  azote  is  almost  always  the  same;  carbonic  acid  is 
the  more  abundant,  as  the  air  is  less  pure.*  This  part  of  natu- 

* This  is  pretty  nearly  the  orig-inal  estimate  of  Lavoisier,  whose  experi- 
ments have  since  been  very  frequently  repeated,  and  with  no  material  differ- 
ence in  tlie  results.  It  is  however  proper  to  recollect  in  speaking  of  the  rela- 
tive proportion  of  the  ingredients  of  the  atmosphere,  that  this  estimate  must 
be  considered- as  having  reference  to  ’weight  and  not  to  measure.  On  this  point 
Lavoisier  is  silent,  as  well  as  most  other  chemical  writers.  It  is  nevertheless 
a fact,  as  has  been  more  particularly  shown  by  Bertholet,  that  the  atmosphere 
contains  only  twenty-two  parts  of  oxygen,  in  the  hundred,  by  measure. 

By  some  chemists  it  has  been  supposed,  from  the  circumstance  of  the  car- 
bonic acid  being  generally  found  in  a larger  quantity  near  the  earth,  that  it  is 
an  accidental,  and  not  an  essential  constituent  of  the  atmosphere.  But  by  De 
Saussure  it  was  detected  in  the  air,  on  the  summit  of  Mont  Blanc;  and  from 
this,  and  a variety  of  other  considerations,  it  would  appear  to  be  a uniform 
part  of  atmospheric  air,  existing  most  probably  in  a state  of  chemical  com- 
bination.— Ed. 


220 


OP  RESPIRATION'. 


ral  philosophy,  which  is  called  eudiometr)’^,  or  the  measurement 
of  the  purity  of  the  air,  is  far  from  accomplishing  what  its  name 
indicates,  and  has  disappointed  the  hopes  which  had  been  enter- 
tained on  the  subject.  Eudiometrical  instruments  can  inform  us 
only  of  the  proportion  of  oxygen  contained  in  the  atmosphere; 
now  its  salubrity,  its  fitness  for  respiration,  is  not  in  proportion 
to  the  quantity  of  oxygen.  The  volatilized  remains  of  putrid 
animal  or  vegetable  substances,  various  mephitic  gases,  com'dne 
with  it,  and  affect  its  purity.  In  the  comparative  anah  sis  of  air 
procured  on  the  Alps  and  in  the  marshes  of  Lombardy,  there 
was  found  in  each  the  same  quantity  of  oxyg  n;  and  ' et  tl’ose 
who  breathe  the  former  enjoy  robust  health,  while  the  inlraoi- 
tants  of  the  marshy  plains  of  Lombardy  are  carried  off  by  epi- 
demic diseases,  are  pale,  emaciated,  and  habitually  lead  a languid 
existence. 

Though  at  least  0,20  of  oxygen  are  necessary  to  render  the 
air  fit  for  respiration,  the  proportion  may  be  diminished  to  seven 
or  eight  parts  in  the  hundred;  but  in  such  cases  the  breathing  is 
laborious,  panting,  and  attended  with  a sense  of  suffocation;  in 
short  asphyxia  comes  on  even  while  the  aii  still  contains  a cer- 
tain quantity  of  oxygen,  of  which  the  lungs  cannot  entirely 
deprive  it.  Whenever  a number  of  persons  are  collected  in  a 
confined  place,  in  which  the  air  cannot  be  easily  renewed,  the 
quantity  of  oxygen  diminishes  rapidly,  that  of  carbonic  acid 
increases.  The  latter,  in  consequence  of  its  specific  gravity,  sinks 
to  the  lowest  part,  and  strikes  with  death  every  living  being 
which  it  envelops.  When  two  lighted  candles  of  different 
lengths  are  placed  under  the  same  bell,  the  shorter  candle  goes 
out  first,  because  the  carbonic  acid  formed  dur  ng  combustion, 
sinks  to  the  most  depending  part.  For  the  same  reason  the  pit 
is  the  most  unhealthy  part  of  a play-house,  when  a great  number 
of  people,  after  remaining  in  it  for  several  hours,  have  deprived 
the  air  of  a considerable  portion  of  its  oxygen. 

Persons  collected  together,  and  enclosed  in  a small  space, 
injure  each  other,  not  only  b)'^  depriving  the  atmosphere  of  its 
respirable  element,  but  particularly  by  altering  its  composi- 
tion by  the  combination  of  all  the  substances  exhaled  from 
their  bodies.  These  volatilized  animal  emanations  become  pu- 
trid while  in  the  atmosphere,  and  conveyed  to  the  lungs  during 


OF  RESPIRATION. 


221 


respiration,  become  the  germ  of  the  most  fatal  diseases.  It  is  in 
this  manner  that  the  jail  and  hospital  fever,  so  fatal  to  almost  all 
whom  it  attacks,  arises  and  spreads.  A dry  and  temperate  air, 
containing  0,27  of  oxygen  and  0,73  of  azote,  and  free  of  other 
gases  or  other  volatilized  substances,  is  the  fittest  for  respira» 
tion.  In  certain  cases  of  disease,  however,  this  function  is  most 
freely  performed  in  a less  pure  air.  Thus  patients  labouring- 
under  pulmonary  consumption,  prefer  the  thick  and  damp  air 
of  low  situations  to  the  sharp  and  dry  air  of  mountains;  nervous 
women  prefer  that  in  which  horn,  feathers,  or  other  animal  sub- 
stances are  burning.  An  atmosphere  highly  electrical,  at  the 
approach  of  a storm,  renders  respiration  very  laborious  in  some 
cases  of  asthma.  In  short,  the  qualities  of  the  air  must  be  suit- 
ed to  the  condition  of  the  vital  power  in  the  lungs,  as  those  of 
the  food  to  the  sensibility  of  the  stomach. 

Being  obliged,  on  this  subject,  to  content  myself  with  the  un- 
gracious office  of  compiler,  I hasten  to  bring  this  article  to  a 
close,  and  to  refer  the  reader  for  a fuller  account  of  the  air,  con- 
sidered in  its  physical  and  chemical  relations,  to  the  works  of 
M.  M.  Fourcroy,  Hauy,  Brisson,  &c.  to  that  of  M.  Guyton 
Morveau  on  the  method  of  purifying  the  air,  when  from  different 
combinations  it  is  become  unfit  for  respiration. 

LXXI.  In  man  and  in  all  warm-blooded  animals,  with  a 
heart  containing  two  auricles  and  two  ventricles,  the  blood 
which  has  been  conveyed  to  all  the  organs  by  the  arteries,  and 
which  has  been  brought  back  by  the  veins  to  the  heart,  cannot 
return  to  it,  without  having  previously  passed  through  the  lungs, 
which  are  viscera  destined  to  the  transmission  of  air;  of  a spun- 
gy texture,  and  through  which  the  blood  must,  of  necessity,  cir- 
culate, to  get  from  the  right  to  the  left  cavities  of  the  heart.  This 
course  of  the  blood  constitutes  the  pulmonary  or  lesser  circula- 
tion: it  does  not  exist  in  some  cold-blooded  animals.  In  reptiles, 
for  instance,  the  heart  has  but  one  auricle  and  one  ventricle; 
the  pulmonary  artery,  in  them,  arises  from  the  aorta  and  con- 
veys but  a small  proportion  of  the  blood;  hence  the  habitual 
temperature  of  these  animals  is  much  lower  than  that  of  man. 
For  the  same  reason  too,  there  exists  so  small  a difference  be- 
tween their  venous  and  arterial  blood;  the  quantity  of  fluid  vivi- 
fied by  exposure  to  the  air,  in  the  pulmonary  tissue,  being  too 


222 


OF  RESPIRATION. 


smaL'  to  effect,  by  its  union  with  the  general  mass,  a material 
change  on  its  qualities. 

Mayow  has  given  the  most  accurate  notion  of  the  respiratory 
organ,  by  comparing  it  to  a pair  of  bellows  containing  an  empty 
bladder,  the  neck  of  which,  by  being  adapted  to  that  of  the  bel- 
lows, should  admit  air  on  drawing  asunder  its  sides.  The  air,  in 
fact,  enters  the  lungs  only  when  the  chest  dilates  and  enlarges, 
by  the  separation  of  its  parietes.  The  agents  of  respiration,  are, 
therefore,  the  muscles  which  move  the  parietes  of  the  chest, 
these  are  formed  of  osseous  and  soft  parts,  in  such  a manner,  as 
to  possess  a solidity  proportioned  to  the  importance  of  the  or- 
gans which  the  chest  contains,  besides  a capacity  of  motion  re- 
quired to  carry  on  the  functions  intrusted  to  them. 

To  carry  on  respiration,  which  may  be  defined  the  alternate 
ingress  of  air  into  the  lungs,  and  its  egress  from  those  organs,  it 
is  necessary  that  the  dimensions  of  the  chest  should  be  enlarged 
(this  active  dilatation  of  the  cavity  of  the  chest  is  called  inspi- 
ration),  and  that  it  should  contract  to  expel  the  air  which  it  had 
received  during  the  first  process.  This  second  action  is  called 
expiration,  it  is  always  of  shorter  duration  than  the  former,  its 
agents  are  more  mechanical,  and  the  muscles  have  much  less  in- 
fluence upon  it. 

The  parietes  of  the  chest  are  formed,  at  the  back  part,  by  the 
vertebral  column,  at  the  fore  part  by  the  sternum,  and  on  the 
sides  by  the  ribs  which  are  osseo -cartilaginous  arches,  situated 
obliquely  between  the  vertebral  column  which  is  fixed  and  be- 
comes the  point  of  support  of  their  motions,  and  the  sternum 
which  is  somewhat  moveable — the  spaces  between  the  ribs  are 
filled  by  muscular  planes  of  inconsiderable  thickness,  the  inter- 
nal and  external  intercostal  muscles,  the  fibres  of  which  lie  in 
opposite  directions. — Besides,  several  muscles  cover  the  outer 
part  of  the  thorax,  and  pass  from  the  ribs  to  the  neighbouring 
bones:  as  the  subclavian  muscles,  the  great  and  lesser  pectorals, 
the  serrati,  the  latissimi  dorsi,  the  scaleni,  the  longissimi  dorsi, 
the  sacro  lumbales,  and  the  serrati  minores,  posterior,  superior, 
and  inferior.  But  of  all  the  muscles  which  form  the  anterior,  pos- 
terior, and  lateral  parietes  of  the  chest,  the  most  important  is  the 
diaphragm,  a fleshy  and  tendinous  partition,  lying  horizontally 
between  the  chest  and  the  abdomen,  which  it  divides  from  each 


OF  RESPIRATION. 


223 


Other;  it  is  attached  to  the  cartilages  of  the  false  ribs,  and  to  the 
lumbar  vertebrae,  and  has  three  openings  to  transmit  the  (Esopha- 
gus and  the  vessels  which  pass  from  the  abdomen  to  the  chest, 
or  from  the  latter  into  the  abdomen. 

In  health,  the  chest  dilates  only  by  the  descent  of  the  dia- 
phragm. The  curved  fibres  of  that  muscle,  straightened  in  con- 
traction, descend  towards  the  abdomen,  and  compress  the  vis- 
cera. The  descent  of  the  viscera  thrusts  forward  the  anterior  pa- 
rietes  of  that  cavity,  and  these  recede,  when  on  expiration  taking 
place  after  inspiration,  the  diaphragm  now  relaxed,  rises,  press- 
ed upward  by  the  abdominal  viscera,  compressed  themselves  by 
the  large  muscles  of  the  abdomen.  But  when  it  is  necessary  to 
take  into  the  chest  a great  quantity  of  air,  it  is  not  sufficient  that 
it  should  be  enlarged  merely  by  the  descent  of  the  diaphragm, 
it  is  required  besides,  that  its  dimensions  should  be  increased  in 
every  direction.  The  intercostal  muscles  then  contract,  and 
tend  to  bring  together  the  ribs  between  which  they  are  situated. 
The  intercostal  spaces,  however,  become  wider,  especially  at 
their  anterior  part,  for  whenever  lines  falling  obliquely  on  a ver- 
tical line,  change  their  direction,  approaching  to  a right  angle, 
the  intermediate  spaces  receive  the  greater  increase,  as  the  lines, 
more  oblique  at  first,  become  at  last  more  nearly  horizontal.  Be- 
sides, as  the  ribs  are  curved  in  the  course  of  their  length,  in  two 
directions,  and  both  in  the  direction  of  their  faces,  and  edgewise, 
the  convexity  of  the  first  curvature  is  outwards,  the  ribs  recede 
to  a distance  from  the  axis  of  the  chest,  whose  cavity  is  en- 
larged transversely,  while  the  second  curvature  (in  the  direc- 
tion of  their  edge)  being  increased  by  a real  twisting  of  these 
bones,  and  which  reaches  to  the  cartilaginous  parts,  the  sternum 
is  heaved  forward  and  upward,  so  that  the  posterior  extremity 
of  the  ribs  is  removed  from  their  sternal  end.  But  as  the  ribs  are 
not  all  equally  moveable,  as  the  first  is  almost  always  invariably 
fixed,  and  as  the  others  are  moveable  in  proportion  to  their 
length,  the  sternum  is  tilted  in  such  a way  that  the  lowermost 
extremity  is  thrust  forward.  The  diameter  of  the  chest  from  the 
fore  to  the  back  part  increases,  therefore,  as  well  as  the  trans- 
verse diameter.  This  increase  of  dimensions  has  been  estimated 
at  two  inches  to  each  of  these  diameters;  the  dimensions  of  the 


224 


OF  RESPIRATIO^‘. 


vertical  diameter,  which  are  regulated  by  the  depression  of  the 
diaphragm,  are  much  greater. 

LXXII.  Professor  Sabatier,  in  his  memoir  on  the  motion  of 
the  ribs,  and  on  the  action  of  the  intercostal  muscles,  maintains, 
that  during  the  act  of  inspiration,  the  upper  ribs  alone  rise,  that 
the  lower  ribs  descend  and  slightly  close  on  the  chest,  while  the 
middle  ribs  project  outwardly;  and  that  in  expiration,  the  former 
set  of  ribs  descend,  that  the  latter  start  a little  outwardly,  and 
that  the  middle  set  encroach  on  the  cavity  of  the  chest.  The 
learned  Professor  adds,  that  the  cartilaginous  articulating  sur- 
faces, by  which  the  ribs  are  connected  to  the  transverse  pro- 
cesses of  the  vertebrtE,  appear  to  him  to  favour  these  different 
motions,  as  the  direction  of  the  articulations  of  the  upper  ribs,  is 
upward,  and  that  of  the  lower,  downward:  but  on  considering 
the  subject  with  attention,  it  will  be  seen,  that  the  surfaces  by 
which  the  transverse  processes  of  the  vertebrae  are  articulated  to 
the  tuberosities  of  the  ribs,  are  turned  directly  forward  in  the 
greatest  number,  some  of  the  lower  ribs  are,  at  the  same  time, 
directed  slightly  upward.  If  we  examine  the  action  of  the  bones 
of  the  chest,  during  inspiration,  in  a very  thin  person,  for  exam- 
ple, in  phthisical  patients,  whose  bones  are  covered  with  little 
else  than  skin,  we  shall  find,  that  all  the  ribs  rise  and  are  carried 
somewhat  outwardly.  It  ^is  not  easy  to  conceive  how  the  inter- 
costal muscles,  which  Professor  Sabatier  considers  as  the  agents 
of  expiration,  should  elevate  the  upper  ribs  and  depress  the 
lower.  The  diaphragm,  whose  circumference  is  inserted  in  the 
latter,  might,  by  its  contraction,  produce  this  effect;  but  as  the  in- 
tercostals  have  their  fixed  point  of  action  in  the  upper  ribs,  they 
oppose  and  neutralize  this  effort,  and  all  the  ribs  are  elevated  at 
once.  If  this  were  not  the  case,  the  ribs  ought  to  be  depressed 
whenever  the  intercostals  contract,  since  the  lowermost,  fixed  by 
the  diaphragm,  would  become  the  fixed  point  on  which  all  the 
others  should  move. 

As  the  fibres  of  the  external  and  internal  intercostal  muscles 
are  in  direct  opposition  to  each  other,  those  of  the  former  set  of 
muscles  having  an  oblique  direction  from  above  downward,  and 
from  behind  forward,  and  crossing  the  fibres  of  the  other  set 
whose  obliquity  is  in  a different  direction;  several  physiologists 
have  thought,  that  these  musdes  were  opposed  to  each  other. 


OF  RESPIRATION. 


225 


that  the  internal  Intercostal  muscles  brought  together  the  ribs, 
after  they  had  been  separated  by  the  external  intercostals,  the 
one  set  being  muscles  of  expiration,  while  the  other  set  con- 
tracted during  inspiration. 

It  is  well  known  with  what  pertinacity  Hamberger,  in  other 
respects  a physiologist  of  considerable  merit,  defended  this 
erroneous  opinion,  in  his  dispute  with  Haller;  it  is  now,  how- 
ever, ascertained,  that  all  the  intercostal  muscles  concur  in  di- 
lating the  chest,  and  that  they  ought  to  be  ranked  among  the 
agents  of  inspiration,  because  the  unequal  capacity  of  motion  in 
the  ribs,  pre'ventsthe  internal  intercostals,  the  lower  insertion  of 
which  is  nearer  to  the  articulation  of  these  bones  to  the  vertebras, 
from  depressing  the  upper  ribs.  Of  the  very  conclusive  experi- 
ments by  which  Haller  undertook  to  refute  the  arguments  of  his 
adversary,  I shall  relate  only  that  which  is  performed  by  strip- 
ping the  parietes  of  the  chest,  in  a living  animal,  of  all  the  mus- 
cles which  cover  it,  and  by  removing,  in  different  parts  of  the 
thorax,  some  of  the  external  intercostal  muscles.  The  internal 
intercostals  are  then  seen  to  contract  during  inspiration,  to- 
gether with  the  remaining  external  intercostals.  These  muscles, 
therefore,  have  a common  action,  and  are  not  in  opposition  to 
each  other.  The  same  experiment  serves  to  prove  the  increased 
dimensions  of  the  space  between  the  ribs.  On  holding  one’s 
finger  between  two  of  the  ribs,  it  feels  less  confined,  when  during 
inspiration,  these  bones  rise  and  thrust  forward  the  sternum. 

This  question  being  at  rest,  although  in  the  pursuit  of  science 
one  should  inquire  how  things  are  effected,  and  not  wherefore 
they  come  to  pass,  one  feels  naturally  desirous  to  know  wnat 
purpose  is  answered  by  the  different  direction  of  the  fibres  of 
the  two  sets  of  intercostal  muscles;  and  with  what  view  Nature 
has  departed  from  her  wonted  simplicity,  in  giving  to  their 
fibres  opposite  directions.  In  answer  to  this  one  may  observe, 
that  the  action  of  powers  applied  obliquely  to  a lever,  being  de- 
composed in  consequence  of  that  obliquity,  a part  of  the  action 
of  the  external  intercostals  would  tend  to  draw  the  ribs  towards 
the  vertebral  column,  which  could  not  happen  without  forcing 
back  the  sternum,  if  the  internal  intercostals  did  not  terd  to 
bring  forward  the  ribs,  at  the  same  time  that  they  elevate  them; 
so  that  these  two  muscular  planes,  united  in  their  action  of 

2 F 


226 


OF  RESPIRATION. 


raising  the  ribs,  antagonize  and  reciprocally  neutralize  each 
other  in  the  effort  by  which  they  tend  to  draw  them  in  different 
directions. 

To  this  advantage  of  mutually  correcting  the  effects  that 
would  result  from  their  respective  obliquity,  may  be  added  the 
benefit  arising  from  a texture  capable  of  a greater  resistance;  it 
is  clearly  obvious  that  a tissue  whose  threads  cross  each  other, 
is  firmer  than  one  in  which  all  the  threads,  merely  in  juxta  posi- 
tion or  united  by  means  of  another  substance,  should  all  lie  in 
the  same  direction.  Hence  Nature  has  adopted  this  arrange- 
ment in  the  formation  of  the  muscular  planes  constituting  the 
anterior  and  lateral  parietes  of  the  abdomen,  without  which  the 
abdominal  viscera  would  frequently  have  formed  herniary  tu- 
mours by  separating  the  fibres,  and  getting  engaged  between 
them.  In  this  respect,  one  may  compare  the  tissue  of  the  abdo- 
minal parietes,  in  which  the  fibres  of  the  external  and  internal 
oblique  muscles,  which  cross  each  other,  are  themselves  crossed 
by  the  fibres  of  the  transversales,  to  the  tissue  of  those  stuffs 
whose  threads  cross  each  other,  or  rather  to  wicker  work,  to 
which  basket  makers  give  so  much  strength,  by  interweaving  the 
osier  in  a variety  of  directions. 

LXXIII.  When  from  any  cause  respiration  becomes  diffi- 
cult, and  the  diaphragm  is  prevented  from  descending  towards 
the  abdomen,  or  the  motion  of  inspiration  impeded,  in  any  way, 
the  intercostals  are  not  alone  employed  in  dilating  the  chest, 
but  are  assisted  by  several  other  auxiliary  muscles;  the  scaleni, 
the  subclavii,  the  pectorals,  the  serrati  magni,  and  the  latissirai 
dorsi,  by  contracting  elevate  the  ribs,  and  increase,  in  more  di- 
rections than  one,  the  diameter  of  the  chest.  The  fixed  point  of 
these  muscles  then  becomes  their  moveable  point,  the  cervical 
column,  the  clavicle,  the  scapula,  and  the  humerus,  being  kept 
fixed  by  other  powers,  which  it  is  unnecessary  to  enumerate. 
Whoever  witnesses  a fit  of  convulsive  asthma,  or  of  a suffocating 
cough,  will  readily  understand  the  importance  and  action  of  these 
auxiliary  muscles. 

Inspiration  is  truly  a state  of  action,  an  effort  of  contractile 
organs,  which  must  cease  when  these  are  relaxed.  The  expira- 
tion which  follows  is  passive,  and  assisted  by  very  few  muscles, 
and  depends  chiefly  on  the  re-action  of  the  elastic  parts  entering 


OF  RESPIRATION. 


S27 

into  the  structure  of  the  parietes  of  the  chest.  We  have  seen 
that  the  cartilages  of  the  ribs  are  pretty  considerably  twisted, 
so  as  to  carry  outward  and  downward  their  upper  edge:  when 
the  cause  which  occasions  this  twisting  ceases  to  act,  these  parts 
return  to  their  natural  condition,  and  bring  back  the  sternum 
towards  the  vertebral  column,  towards  which  the  ribs  descend, 
from  their  weight.  The  diaphragm  is  forced  towards  the  chest 
by  the  abdominal  viscera,  which  are  compressed  by  the  broad 
muscles  of  the  abdomen. 

In  every  effort  of  expiration,  as  in  cough  and  vomiting,  these 
muscles  re-act,  not  merely  by  their  own  elasticit}’,  but  they 
besides  contract  and  tend  to  approach  towards  the  vertebral 
column,  by  pressing  upwards  the  abdominal  viscera  towards  the 
chest.  The  triangularis  sterni,  the  subcostales,  and  the  serratus 
inferior  posticus,  may  likewise  be  ranked  among  the  agents  of 
expiration;  but  they  appear  to  be  seldom  employed,  and  to  be 
too  slender  and  weak  to  contribute  much  to  the  contraction  of 
the  chest. 

LXXIV.  When  the  chest  enlarges,  the  lungs  dilate  and  fol- 
low its  parietes,  as  these  recede  from  each  other.  These  two 
viscera,  soft,  spungy,  and  of  less  specific  gravity  than  water, 
covered  by  the  pleura  which  Is  reflected  over  them,  are  always 
in  contact  with  the  portion  of  that  membrane  which  lines  the 
cavity  of  the  thorax;  no  air  is  interposed  between  their  surfaces 
(which  are  habitually  moistened  by  a serous  fluid  exuding  from 
the  pleura)  and  that  membrane,  as  may  be  seen  by  opening, 
under  water,  the  body  of  a living  animal,  when  no  air  will  be 
seen  to  escape.  As  the  lungs  dilate,  their  vessels  expand,  and 
the  blood  circulates  through  them  more  freely;  the  air  contain- 
ed in  the  innumerable  cells  of  their  tissue  becomes  ratified,  in 
proportion  as  the  space  in  which  it  is  contained  is  enlarged. 
Besides,  the  warmth  communicated  to  it  by  the  surrounding 
parts,  enables  it,  in  a very  imperfect  manner,  to  resist  the  pres- 
sure of  the  atmosphere,  rushing  through  the  nostrils  and  mouth 
into  the  lungs,  by  the  opening  in  the  larynx  which  is  always  per- 
vious, except  during  deglutition. 

LXXV.  The  pulmonary  tissue  into  which  the  air  is  thus  drawn 
in,  every  time  the  capacity  of  the  chest  is  increased,  does  not 
consist  merely  of  air-vessels,  which  are  but  branches  of  different 


228 


OF  RESPIRATION. 


sizes  of  the  two  principal  divisions  of  the  trachea,  but  is  formed 
likewise  by  the  lobular  tissue  into  which  those  canals  deposit 
the  air;  it  contains  also  a great  quantity  of  lymphatics  and  blood 
vessels,  of  glands  and  nerves.  Cellular  tissue  unites  together  all 
these  parts,  and  forms  them  into  two  masses  covered  over  by 
the  pleura,  and  of  nearly  the  same  bulk,*^  suspended  in  the  chest 
from  the  bronchise  and  trachea,  and  every  where  in  contact  with 
the  parietes  of  the  cavities  of  the  chest,  except  towards  their 
root,  at  which  they  receive  all  their  nerves  and  vessels. 

The  pulmonary  artery  arises  from  the  base  of  the  right  ventri- 
cle, and  divides  into  two  arteries,  one  to  each  lung.  On  reaching 
the  substance  of  these  viscera,  these  vessels  divide  into  as  many 
branches  as  there  are  principal  lobes.  From  these  branches  there 
arise  others,  which  again  subdivide  into  lesser  ones,  until  they 
become  capillary,  and  continuous  with  the  radicles  of  the  pul- 
monary veins. 

These  vessels,  formed  from  the  extremities  of  the  artery, 
unite  into  trunks,  which  progressively  enlarging,  emerge  from 
the  lungs,  and  open,  four  in  number,  into  the  left  auricle.  Be- 
sides these  large  vessels,  by  means  of  which  the  cavities  in  both 
sides  of  the  heart  communicate  together,  the  lungs  receive  from 
the  aorta  tw'o  or  three  arteries  called  bronchial  arteries:  these 
penetrate  into  their  tissue,  and  follow  the  direction  of  the  other 
vessels,  and  terminate  in  the  bronchial  veins,  which  open  in  the 
superior  cava,  not  fa.r  from  its  termination  into  the  right  auricle. 
These  bronchial  vessels  are  sufficient  for  the  nourishment  of  the 
pulmonary  organ,  which,  n realiu,  is  not  near  so  bulky  as  it 
appears,  as  may  be  ascertained  by  examining  the  lungs,  after  all 
the  air  has  been  extracted  from  them,  by  means  of  an  air  pump 
applied  to  the  trachea. 

Physiologists,  for  the  most  part,  consider  the  bronchial  arte- 
ries as  the  nutritious  vessels  of  the  lungs.  They  assert,  that  as 
the  blood  which  flows  along  he  branches  of  the  pulmonary 
artery  resembles  venous  blood,  it  is  unfit  for  the  nutrition  of  the 
lungs,  and  that  it  was  necessary  that  these  organs  should  be 
supplied  by  arteries  arising  from  the  aorta,  and  containing  blood 

* It  is  well  known  that  the  right  lung  is  larger  than  the  left,  that  it  is  divided 
into  three  principal  lobes,  while'the  latter  has  only  two. 


ON  RESPIRATION. 


analogous  to  that  which  is  sent  to  every  part  of  the  body.  But 
though  it  be  admitted,  that  this  venous  blood,  brought  from 
every  part  of  the  body,  and  sent  into  the  lungs  by  their  principal 
artery,  may  not  be  €t  to  maintain  the  organ  in  its  natural  eco- 
nomy, this  blood  is  fit  for  that  use,  when  after  being  made  hot, 
spumous,  and  florid  by  the  absorption  of  the  atmospherical 
oxygen,  it  returns  by  the  pulmonary  veins  into  the  left  cavities 
of  the  heart.^ 

Some  have  thought  that  the  blood  which  flows  in  the  bron- 
chial vessels,  exposed  to  the  action  of  the  air,  like  the  portion 
of  this  fluid  which  traverses  the  pulmonary  system,  lost  nothing 
of  its  arterial  qualitiesj  and  that,  poured  by  the  bronchial  veins 
into  the  superior  or  descending  vena  cava,  it  was  a necessary 
stimulus  for  the  right  cavities  of  the  heart,  ol  which  blood  en- 
tirely dark  and  venous  would  not  have  awakened  the  contrac- 
tility. But  even  if  the  experiments  of  Goodwin  had  not  proved 
that  the  parietes  of  these  cavities  have  a sensibility  relative  to 
dark  blood,  by  virtue  of  which  the  stimulus  is  sufficient  to  deter- 
mine their  contraction,  the  action  of  the  heart  does  not  depend  so 
closely  as  has  been  said  on  the  impression  of  the  blood  on  its  sub- 
stance, since  it  contracts  though  empty,  and  prolongs  its  contrac- 
tions to  relieve  itself  of  the  black  blood  which  fills  it,  when  an 
animal  dies  of  asphyxia. 

Boerhaave,  who  admitted  one  sort  of  peripneumony  depend- 
ing on  the  obstruction  of  the  bronchial  vessels,  whilst  another, 
according  to  the  same  writer,  depends  on  the  obstruction  of  the 
pulmonary  vessels,  seems  to  justify,  in  some  measure,  the  re- 
proach, exaggerated  unquestionably,  which  some  authors  have 
thrown  out  against  anatomy,  of  having  rather  retarded  than 
accelerated  the  progress  of  the  Hippocratic  practice  of  medi- 

* That  the  bronchial  vessels  exclusively  nourish  tlie  lung-s,  is  an  opinion 
entertained  certainly  by  a majority  of  physiologists.  When,  however,  we 
compare  the  size  of  these  vessels  with  the  magnitude  of  the  office  assigned 
to  them,  it  seems  very  doubtful  whether  they  are  adequate  to  it.  We  are  in- 
clined to  believe,  notwithstanding  what  is  alleged  against  it,  that  the  pulmo- 
nary arteries  also  contribute  to  the  nourishment  of  the  lungs;  and  indeed  there 
is  a fiict  which  almost  proves  it.  We  allude  to  the  circumstance  of  the  pulmo- 
nic adhesions,  which  are  supposed  to  take  place  in  consequence  of  inflamma- 
tion, having  been  repeatedly  injected  from  the  trunk  of  the  pulmonary  arte- 
ries.— Eb. 


230 


OF  RESPIRATION. 


cine.  The  anatomical  ana'ysis  of  the  lungs,  or  the  distinction  of 
the  tissues  which  enter  into  their  composition,  furnishes  juster 
ideas  on  the  difference  of  the  inflammations  by  which  they  may 
be  attacked.  It  has  been  seen,  that  of  these  pulmonary  phleg- 
masias,  the  commonest  and  least  serious  catarrh  consists  in 
inflammation  of  the  mucous  membrane  which  lines  the  air  pas- 
sages, whilst  the  real  peripneumony  has  its  seat  in  the  paren- 
chyma of  the  organ,  which  it  converts  into  a hard  and  compact 
mass.  It  is  this  state  that  anatomists  have  long  designated  under 
the  name  of  hepatization^  because,  in  fact,  the  substance  of  the 
lung  has  acquired  the  hardness,  the  weight,  and  something  of 
the  appearance  of  the  liver.  The  same  anatomical  researches 
have  shown  that  pleurisy  consists  in  inflammation  of  the  pleura, 
and  of  the  surface  of  the  lung;  an  inflammation  which  some- 
times leaves  no  trace,  but  which  oftener  exhibits,  on  the  opening 
of  bodies,  the  pleura  thickened  and  opaque,  covered  with  a 
layer  of  coagulable  lymph,  whitish,  more  or  less  thick,  or  even 
adhering  to  the  lung.* 

There  arise  from  the  surface  and  from  the  internal  substance 
of  the  lungs,  a prodigious  number  of  absorbents,  which  may  be 
divided  into  superficial  and  deep  seated.  The  latter  accompany 
the  bronchial  tubes  and  penetrate  into  the  substance  of  the  glan- 
dular bodies  situated  where  those  air  vessels  divide,  but  col- 

* These  adhesions  of  the  lung'  to  the  pleura  costalis  are  so  common,  that 
the  old  anatomists  considered  them  as  a natural  disposition,  and  called  them 
ligaments  of  the  lungs.  It  has  been  believed  till  now,  that  these  adhesions 
arose  from  the  organization  of  a substance  transuding  from  the  two  surfaces. 
Numerous  dissections  have  convinced  me,  that  in  all  the  points  where  they 
are  met  with,  the  pleura  has  disappeared,  that  it  is  decomposed,  and  that 
■whether  it  be  at  the  surface  of  the  lungs,  or  within  the  ribs  and  their  mus- 
cles, it  is  produced  b)^  the  act  of  inflammation,  that  it  is  become  celbular 
by  the  thinning  of  its  tissue  and  the  separation  of  its  lamiiis.  The  pleura  thus 
reduced  to  cellular  tissue,  the  adhesion  is  produced  by  the  first  intention,  in 
the  same  way  as  In  simple  wounds  immediately  united.  There  is  no  organ  that 
abounds  more  than  the  lungs  in  facts  important  to  morbid  anatomy.  The 
variety  of  appearances  they  exhibit,  on  the  opening  of  bodies,  are  almost  innu- 
merable; and  to  give  one  instance,  the  pleura  appears  after  pleurisy  in  five 
perfectly  distinct  conditions.  1st.  In  its  natural  state,  when  the  disease  being 
incipient  and  slight,  the  resolution  is  effected  at  the  moment  of  death: — 2dly- 
When  it  is  red,  thickened,  andopake: — 3dly.  When  it  is  covered  witli  coagu- 
lable lymph: — 4thly.  When  it  adheres: — 5thly.  When,  in  consequence  of 
chronic  inflammation,  hydrothorax  has  taken  place,  &c.  8tc. 


OF  RESPIRATION, 


231 


Iccted,  in  greatest  number,  towards  the  root  of  the  lungs  and  at 
the  angle  formed  by  the  bifurcation  of  the  trachea.  These  bron- 
chial glands,  belonging  to  the  lymphatic  system,  do  not  differ 
from  the  glands  of  the  same  kind,  and  are  remarkable  only  by 
their  number,  their  size,  and  their  habitually  darkish  colour. 
The  absorbents  of  the  lungs,  after  ramifying  in  these  glands,  ter- 
minate in  the  upper  part  of  the  thoracic  duct,  at  the  distance  of 
a few  inches  from  its  termination  into  the  subclavian  vein. 
Lastly,  the  lungs,  though  endowed  with  a very  imperfect  degree 
of  sensibility,  have  a pretty  considerable  number  of  nerves  fur- 
nished by  the  great  sympathetic,  and  especially  by  the  eighth 
pair. 

It  was  long  believed,  on  the  authority  of  Willis,  that  the  aerial 
tissue  of  the  lungs  is  vesicular,  that  each  ramification  of  the 
bronchiae  terminated  in  their  substance,  in  the  form  of  a small 
ampullula;  but  at  present,  most  anatomists  adopt  the  opinion  of 
Helvetius,  according  to  whom  every  air-vessel  terminates  in  a 
small  lobe,  or  kind  of  spunge  fitted  for  the  reception  of  air  and. 
formed  of  a number  of  cells  communicating  together.  These 
lobes,  united  by  cellular  tissue,  form  large  lobes,  and  these  to- 
gether form  the  mass  of  the  lungs. 

The  tissue  that  connects  together  the  different  lobes,  is  very 
different  from  that  in  which  the  ramifications  of  the  bronchise  ter- 
minate; air  never  penetrates  in  it,  except  when  the  tissue  of  the 
air  cells  is  ruptured.  On  such  occasions,  which  are  not  of  rare 
occurrence,  on  account  of  the  excessive  thinness  of  the  laminae 
of  the  air  cells  of  that  tissue,  the  lung  loses  its  form,  and  be- 
comes emphysematous.  Haller  estimates  at  about  the  thousandth 
part  of  an  inch,  the  thickness  of  the  parietes  of  the  air  cells,  and. 
as  the  extreme  ramifications  of  the  pulmonary  vessels  are  distri- 
buted on  these  parietes,  the  blood  is  almost  in  immediate  con- 
tact with  the  air.  There  can  be  no  doubt,  that  the  oxygen  of  the 
atmosphere  acts  on  the  blood,  under  such  circumstances,  since 
it  alters  its  qualities  and  communicates  to  it  a florid  red  colour^ 
when  inclosed  in  a pig’s  bladder  and  placed  under  a vessel  filled 
with  oxygen  gas. 

LXX  VI.  Every  time  the  chest  dilates,  in  an  adult,  there  enter 
into  the  lungs  between  thirty  and  forty  cubic  inches  of  atmos- 


232 


OF  RESPIRATION. 


pherical  air.*  When  the  air  has  been  exposed,  for  a few  mo- 
ments, in  the  pulmonary  tissue,  it  is  expelled  by  the  eff  ..rt  ;f  ex- 
piration, but  it  is  diminished  in  quantity  and  is  reduced  to 
thirty-eight  inches.  Its  composition  is  no  longer  the  same,  it  con- 
tains, it  is  true,  0,73  of  azote,  but  the  vital  portion  fit  for  respi- 
ration, the  oxygen,  has  undergone  a great  diminution,  its  pro- 
portion is  only  0,14:  carbonic  acid  forms  the  remaining  thirteen 
hundredths,  and  there  are  sometimes  found  one  or  two  parts  of 
hydrogen.  It  is  besides  affected  by  the  addition  of  an  aqueous 
vapour,  which  is  condensed  in  cold  weather,  as  it  escapes  at  the 
mouth  and  nostrils.  It  is  called  the  humour  of  the  pulmonary 
transpiration.  These  changes,  compared  to  those  which  the 
blood  experiences  in  passing  through  the  lungs,  clearly  show  a 
reciprocal  action  of  this  fluid  a d of  the  oxygen  of  the  atmos- 
phere. rhe  dark  venous  blood  which  coagulates  slowly  and 
which  then  disengages  a considerable  quantity  of  serum  abound- 
ing in  hydrogen  and  carbon,  and  of  a temperature  of  only  thirty 
degrees,  yields  its  hydrogen  and  carbon  to  the  oxygen  of  the  at- 
mosphere, to  form  carbonic  acid  and  the  pulmonary  vapour:  and 
as  oxygen  cannot  enter  into  these  new  combinations,  without 
parting  with  a portion  of  the  caloric  which  keeps  it  in  a state  of 
gas,  the  blood  acquires  this  warmth,  which  is  disengaged  the 
more  readily,  according  to  the  ingenious  experiments  of  Craw- 
ford, as  by  parting  with  its  hydrogen  and  carbon,  its  capacity  for 
caloric  increases  in  the  proportion  of  10  : 11.5. 

* Some  physiolog-ists  think  that  the  quantity  of  air  inspired  is  much  less  con- 
siderable.  Professor  Gregory,  of  Edinburgh,  states,  in  his  public  lectures,  that 
scarcely  two  inches  of  air  enter  into  the  lungs,  at  each  inspiration,  it  may  be 
proved,  however,  that  this  calculation  is  inaccurate;  either  by  drawing  a full 
inspiration,  as  was  done  by  Mayow,  at  the  expense  of  a certain  qua  :iity  of  air 
contained  in  a bladder,  or  b}'  breathing  into  a vessel  connected  with  a pneuma- 
tic apparatus,  the  air  taken  in  by  drawing  a deep  inspiration  Or  else  one 
may  inflate  the  lungs  of  a dead  body,  by  adapting  to  the  trachea  a stop-cock 
connected  with  a curved  tube  to  receive  the  air  under  a vessel  of  the  same  ap- 
paratus. Various  means  have  been  employed  to  measure  the  capacity  of  the 
chest.  Boerhaave  placed  a man  in  a tub  containing  water  above  his  shoulders, 
he  then  made  him  take  a deep  inspiration,  and  measured  the  height  at  which 
the  fluid  rose  from  the  dilatation  of  the  chest  Keill  injected  water  into  the 
chest  of  a dead  body.  Lastly,  it  has  been  proposed  to  inject  the  bronchial  tube* 
and  the  lobular  tissue  into  which  tliev  terminate,  with  fusible  metal  consisting 
of  eight  parts  of  pewter,  five  of  lead,  three  of  bismuth,  to  which  may  be  added 
one  of  mercury. 


OF  RESPIRATION. 


233 


In  parting  with  its  carbon  which,  by  uniting  with  oxygen, 
forms  the  carbonic  acid  that  is  thrown  out  during  expirati  on,  the 
blood  loses  its  dark  and  nearly  purple  colour,  and  becomes  of  a 
florid  red,  and  its  consistence  increases  from  the  escape  of  its 
hydrogen  and  of  its  aqueous  parts.  Besides,  as  it  absorbs  a cer- 
tain quantity  of  oxygen,  it  becomes  spumous  ahd  light;  its  con- 
crescibility  and  plasticity  increase,  and  on  coagulating,  there  is 
separated  from  it  a smaller  quantity  of  serum. 

After  parting  with  its  hydrogen  and  carbon,  and  combining 
with  oxygen  and  caloric,  in  its  passage  through  the  lungs,  the 
blood,  which  is  become  arterial,  parts  with  these  two  principles, 
in  proportion  as  in  receding  from  the  heart,  it  forms  new  combi- 
nations, and  is  converted  into  oxides  of  hydrogen  and  carbon, 
which,  on  receiving  an  additional  quantity  of  oxygen,  are 
changed  into  water  and  carbonic  acid,  when  on  being  carried 
along  with  the  venous  blood  into  the  pulmonary  tissue,  they  are 
exposed  to  the  influence  of  the  atmospherical  air. 

The  arterial  blood  becomes  venous  by  yielding  its  oxygen, 
when  any  cause  whatever  suspends  or  slackens  its  course,  as  is 
proved  by  the  following  experiment  of  John  Hunter.  He  tied 
the  carotid  artery  of  a dog,  with  ligatures  placed  at  the  distance 
of  about  four  inches  from  each  other;  the  blood  contained  in  the 
portion  of  artery  included  between  the  two  ligatu*  es,  on  laying 
open  this  part  of  the  vessel,  at  the  end  of  a few  hours,  vvas  found 
coagulated  and  as  dark  as  that  in  the  veins.  The  blood  contain- 
ed in  an  aneurismal  sac,  and  which  is  frequent!}'-  found  in  a fluid 
state,  when  the  internal  coats  of  the  artery  are  but  lately  rup- 
tured, becomes  venous  after  remaining  in  it  some  time.  The 
changes,  however,  which  the  blood  undergoes  in  its  course 
through  the  arterial  system,  are  not  very  remaikable,  owing  to 
the  rapidity  with  which  it  flows  along  those  vessels;  there  is  less 
difference  between  the  blood  contained  in  an  artery  near  the 
heart,  and  that  contained  in  an  artery  at  a distance  from  that 
organ,  than  in  the  blood  taken  from  the  veins  near  their  extre- 
mities, and  from  the  great  trunks  which  deposit  it  into  the  right 
auricle.  The  blood  in  the  small  veins  resembles  arterial  blood, 
and  .frequently  in  a very  copious  bleeding  the  colour  of  the 
blood,  which,  at  first,  is  very  dark,  gradually  becomes  less  dark, 
till  towards  the  end  of  the  bleeding  it  shows  nearly  the  same 

2G 


OF  RESPIRATION. 


234 

qualities  as  if  arterial;  a phenomenon  which,  as  is  well-observed 
by  the  English  writer  already  quoted,  depends  on  the  more  easy 
and  rapid  flow  of  the  blood  of  the  arteries  into  the  veins,  in  con- 
sequence of  the  evacuation  of  the  venous  system.  This  observa- 
tion is  a complete  refutation  of  the  assertion  of  Bellini,  who 
maintains,  that  when  a vein  is  wounded,  the  blood  which  comes 
from  it  forms  a double  current  which  flows  out  at  the  wound. 
The  above  opinion  is  maintained  by  highly  distinguishing  phy- 
siologists, as  Haller  and  Spallanzani,  who  support  it  by  experi- 
ments performed  on  the  vessels  of  cold-blooded  animals  or  on 
veins  without  valves.  In  bleeding  at  the  bend  of  the  arm,  the 
blood  cannot  come  from  that  part  of  the  vessel  which  is  above 
the  wound:  the  valves  oppose  insuperable  obstacles  to  its  retro- 
grade flow,  hence  it  is  very  easy  to  distinguish  the  red  blood 
which  comes  from  the  lower  extremity  of  the  vein,  from  that 
which  flows  from  the  upper  end,  and  which  is  poured  into  the 
vessel  by  the  veins  which  open  into  it,  between  the  puncture  and 
the  nearest  valve. 

In  its  course  to  the  parts  among  which  the  arteries  are  distri- 
buted, the  blood,  vivified  in  its  passage  through  the  lungs,  and 
fitted,  as  M.  Fourcroy  says,  for  a new  life,  loses  its  oxygen  and 
caloric.  Its  capacity  for  the  latter,  diminishes,  in  proportion  as 
the  oxygen,  by  combining  with  hydrogen  and  carbon,  restores  it 
to  the  venous  state. 

This  theory  of  the  process  by  which  the  Blood  parts  with  its 
oxygen,  in  its  progress  along  the  blood-vessels,  is  rendered  still 
more  probable,  by  recent  discoveries  on  the  nature  of  the  dia- 
mond. This  substance  is  the  only  pure  carbon,  and  that  which 
is  called  so  by  chemists,  is  an  oxide  of  carbon  which  owes  its 
dark  colour  to  the  oxygen  with  which  it  is  combined.  Before 
these  experiments,  it  was  not  easy  to  determine  the  particular 
condition  of  the  carbon  which  exists  so  plentifully  in  venous 
blood. 

No  precise  calculation  has  yet  been  made  of  the  quantity  of 
oxygen  absorbed  by  the  venous  blood,  nor  of  the  quantity,  em- 
ployed in  the  combustion  of  hydrogen  and  carbon  in  the  lungs, 
so  as  to  form  water  and  carbonic  acid. 

Is  the  carbon,  in  venous  blood,  mereh’^  combined  with  oxygen, 
or  is  it  united  with  hydrogen,  so  as  to  form  carburetted  hydro- 


OF  RESPIRATION. 


235 


gen?  It  appears  to  nae  more  probable,  that  the  oxygen  which  is 
absorbed,  by  combining  with  hydrogen,  in  every  part  of  the 
body,  produces  the  water  which  dilutes  the  venous  blood,  ren- 
ders it  more  fluid,  and  richer  in  serum  than  arterial  blood;  while, 
by  its  union  with  carbon,  it  forms  an  oxide  that  gives  to  the 
blood  the  dark  colour,  which  is  one  of  its  most  remarkable 
characters.  On  reaching  the  lungs,  which  are  real  secretory  or- 
gans, the  water  is  exhaled,  dissolved  in  the  air,  and  forms  the 
pulmonary  transpiration;  the  oxide  of  carbon,  completely  de- 
composed by  an  additional  quantity  of  oxygen,  constitutes  car- 
bonic acid,  which  gives  to  the  air  that  is  expired,  the  power  of 
forming  a precipitate  in  lime  water. 

The  absorption  of  oxygen  by  the  venous  blood,  explains  how 
the  phenomena  of  respiration  are  continued  into  every  part  of  the 
body,  and  produce  the  warmth  uniformly  diffused  over  all  our 
organs.  In  proportion  as  the  blood  parts  with  its  caloric,  for 
which  its  aflSnity  diminishes  as  it  becomes  venous,  the  parts 
which  give  out  their  hydrogen  and  carbon  combine  with  it.  If 
the  lungs  were  the  only  organs  in  tvhich  caloric  might  be  disen- 
gaged, the  temperature  of  those  viscera  ought  considerably  to 
exceed  that  of  other  parts:  experience,  however,  shows  that  the 
temperature  of  the  lungs  is  not  sensibly  more  elevated. 

This  theory  of  respiration,  for  which  we  are  entirely  indebted 
to  modern  chemistry,  is  contradicted  by  no  one  phenomenon. 
The  greater  the  extent  and  capacity  of  the  lungs,  the  more  fre- 
quent is  respiration,  and  the  greater  the  warmth  and  vivacity  of 
animals.  Birds,  whose  lungs  extend  into  the  abdomen  by  vari- 
ous membranous  sacs,  and  whose  bones  are  hollow  and  communi- 
cate with  the  lungs,  consume  a great  deal  of  oxygen,  either  on 
account  of  the  magnitude  of  this  respiratory  apparatus,  or  from 
their  frequent,  and,  at  times,  hurried  respiration.  On  that  ac- 
count, the  habitual  temperature  of  their  body  exceeds  that  of 
man  and  mammiferous  animals.  In  reptiles,  on  the  contrary, 
whose  vesicular  lungs  admit  but  a very  small  quantity  of  blood, 
and  present  to  the  atmosphere  a surface  of  very  limited  extent, 
and  in  which  respiration  is  performed  with  intervals  of  longer 
duration,  the  body  is  at  a temperature  which,  naturally,  never 
rises  above  seven  or  eight  degrees. 

LXXVII.  Though  the  temperature  or  warmth  of  the  body  is 


OF  RESPIRATION. 


236 

generally  proportioned  to  the  extent  of  respiration,  to  the  quan- 
tity of  blood  exposed,  in  a given  time,  to  the  action  of  the  at- 
mospherical air,  it  may  be  higher  or  lower,  according  to  the  de- 
gree of  the  vital  energy  of  the  lungs.  These  organs  should  not 
be  considered  as  mere  chemical  receivers;  they  act  on*’  " T, 
digest  it,  as  the  ancients  said,  and  combine  it  with  the  blood,  by 
a power  which  is  peculiar  to  them.  If  it  were  otherwise,  there 
would  be  nothing  to  prevent  a dead  body  from  being  restored  to 
life,  by  inflating  with  oxygen  its  pulmonary  tissue.  The  ancients 
alluded  to  this  action  of  the  lungs  on  the  air  we  breathe,  by  call- 
ing that  air  the  pabulum  vita.  Its  digestion  was,  they  thought, 
effected  in  the  lungs,  in  the  same  manner  as  the  digestion  in  the 
stomach  of  other  aliments  less  essential  to  life,  and  whose  priva- 
tion may  be  borne  for  a certain  time;  while  life  is  endangered, 
when  the  aeriform  nutriment  ceases  to  be  furnished  to  the  lungs 
for  the  short  space  of  a few  minutes. 

In  proof  of  th£  vitality  of  the  lungs,  and  of  the  share  which 
they  have  in  producing  the  changes  which  the  blood  undergoes 
in  passing  through  them,  I may  mention  the  experiment  which 
proves  that  an  animal  placed  under  a vessel  filled  with  oxygen, 
and  breathing  that  gas  in  a pure  stale,  consumes  no  more  of  it 
that  if  it  was  received  into  the  chest,  mixed  w^ith  other  gases  unfit 
for  respiration.  A guinea-pig,  placed  under  a vessel  full  of  vital 
air  and  of  known  capacity,  will  live  four  times  longer  than  if  the 
vessel  contained  atmospherical  air.  No  remarkable  difference  is 
at  first  perceived  in  the  act  of  respiration,  but  if  the  animal  re- 
mains long  immersed  in  the  oxygen,  his  respiration  becomes 
more  frequent,  his  circulation  more  rapid,  all  the  vital  functions 
are  executed  with  more  energy.  The  1 mgs  separate  by’  a power 
inherent  in  themselves,  the  two  atmospherical  gases,  and  this 
process  is  effected  by  a pretty  considerable  power;  for  oxygen, 
in  its  combination  with  the  blood,  ts,  with  difficulty,  separated 
from  azote.  In  fact,  the  blood,  though  in  thin  layers,  becomes 
dark,  when  exposed  to  the  atmospherical  air. 

It  is  observed,  that  the  purity’  of  the  air  contained  in  the  re- 
ceiver, is  the  more  readily  affected,  as  the  animal  placed  under 
it  is  younger,  more  robust,  and  as  his  lungs  are  more  capacious. 
Hence  birds,  whose  lungs  are  very  large,  contaminate  a consi- 
derable quantity’  of  air,  and  consume  more  quickly  its  respirable 


OF  RESPIRATION. 


237 


part.  A frog,  on  the  contrary,  will  remain  a considerable  time 
in  the  same  quantity  of  air,  without  depriving  it  of  its  oxygen. 

The  vesicular  lungs  of  that  reptile,  as  well  as  of  all  oviparous 
quadrupeds,  are  much  more  irritable  than  those  of  warm- 
blooded animals;  they  appear  to  contract  at  the  will  of  the 
animal.  The  frog  is  without  a diaphragm,  attracts  the  air  into 
its  lungs,  by  swallowing  it  by  a real  process  of  deglutition,  as 
was  pro\  ed  by  Professor  Rafu,  of  Copenhagen,  who  killed  those 
animals  bv  holding  their  jaws  asunder  for  a certain  time.  They 
reject  the  air  by  a contraction  of  the  lungs,  in  the  same  manner 
as  in  man  the  bladder  empties  itself  of  urine. 

In  birds,  whose  diaphragm  is  equally  membranous,  and  con- 
tains several  openings  to  transmit  the  air  into  the  pulmonarv  ap- 
pendices, the  parietes  of  the  thorax  are  likewise  more  moveable 
than  in  man  and  quadrupeds.  Their  pectoral  muscles  are  more 
powerful,  their  ribs  contain  a joint  situated  in  the  middle  of 
those  arches  which  are  completely  ossified  in  that  class  of  ani- 
mals; and  those  two  portions  move  on  each  other,  forming,  at 
their  point  of  union,  angles  more  or  less  acute,  according  to  the 
distance  of  the  sternum  from  the  vertebral  column. 

A numerous  class  of  cold  red-blooded  animals,  viz.  fishes, 
have  no  lungs;  the  gills,  which  supply  their  place,  are  small  pen- 
niform  laminae,  generally  four  in  number,  situated  on  each  side, 
at  the  posterior  and  lateral  part  of  the  head,  covered  over  by  a 
moveable  lid,  to  which  naturalists  give  the  name  of  operculum. 
The  water  which  the  animal  swallows,  passes,  when  he  chooses, 
through  the  parietes  of  the  pharynx,  which  contain  several  prettv 
considerable  openings,  is  spread  over  the  gills  and  the  pulmo- 
nary vessels  which  are  distributed  in  them,  then  escapes  at  the 
auricular  apertures,  when  the  animal  closes  his  mouth,  and 
raises  the  opercula.  It  is  not  known,  whether  the  water  is  de- 
composed and  yields  its  oxygen  to  the  blood  which  circulates  in 
the  gills,  or  whether  the  small  quantity  of  air  that  is  dissolved 
in  the  water,  alone  serves  to  vivify  the  pulmonary  blood.  The 
latter  opinion  seems  the  most  probable,  if  it  be  considered  that 
a fish  may  be  suffocated  by  closing  accurately  the  vessel  of  water 
in  which  it  is  enclosed.  The  same  result  might,  I conceive^  be 
obtained  by  placing  the  vessel  under  the  receiver  of  an  air  pump, 
so  as  to  exhaust  it  completely. 


238 


OF  RESPIRATION. 


Respiration,  which  is  completely  under  the  influence  of  the 
brain,  as  far  as  relates  to  its  mechanism,  is  less  dependent 
upon  it,  in  regard  to  the  action  of  the  lungs  on  the  blood,  and 
the  combination  of  that  fluid  with  oxygen,  which  is  the  essen- 
tial object  of  that  function.  The  nerves,  however,  have  some 
influence  on  that  function,  as  well  as  on  the  various  secretions, 
in  which,  according  to  Bordeu,  they  are  of  first-rate  importance. 
M.  Dupuytren  ascertained  by  his  experiments,  that  the  division 
of  the  cervical  portion  of  the  eighth  pair  of  nerves,  did  not  sen- 
sibly affect  respiration;  but  the  animal  died  with  all  the  symp- 
toms of  asphyxia,  when  this  nerve  was  divided  on  both  sides. 
Death  took  place  in  the  course  of  few  minutes,  when  the  ex- 
periment was  performed  on  horses.  Other  animals  did  not  die 
so  soon  after;  dogs,  for  instance,  have  been  known  to  live 
several  days  after  the  experiment.  By  interrupting  the  com- 
munication between  the  lungs  and  the  brain,  we  paralyze  the 
former  of  these  organs,  and  it  ceases  to  convert  the  venous  into 
arterial  blood.  This  fluid,  conveyed  by  the  pulmonary  artery, 
continues  of  a dark  colour,  when  brought  to  the  left  cavities  of 
the  heart;  the  arteries  convey  the  blood  without  its  having  re- 
ceived its  vivifying  principle,  in  passing  through  the  lungs  which 
are  paralyzed,  by  having  their  nerves  tied  or  divided.  It  is  easy 
to  conceive  that  all  organs,  for  want  of  the  stimulus  which  de- 
termines their  action,  carry  on  their  functions  imperfectly,  and 
at  last  cease  to  act.  The  animal  heat  is  likewise  lowered  a few 
degrees,  as  was  ascertained  by  the  abovementioned  physician, 
who  thinks  he  has  established  as  a fact,  that  the  ligature  of  the 
nerves  of  the  lungs  does  not  destroy,  but  weakens  the  vital 
power,  which  enables  them  to  take  up  the  oxygen  and  to  give 
out  the  carbonic  acid.  The  brain,  therefore,  possesses  a double 
influence  over  the  function  of  respiration;  on  the  one  hand,  it 
directs  its  mechanism  by  means  of  the  nerves  which  it  sends  to 
the  diaphragm,  and  to  the  intercostal  muscles;  and  on  the  other 
hand,  it  is  through  the  nerves  which  arise  from  the  brain,  that 
the  lungs  have  the  power  of  converting  dark  blood  into  arterial 
blood,  which  is  the  principal  phenomenon  of  respiration. 

Experiments  performed  on  the  same  subject  by  Dr.  Gallois, 
subsequent  to  those  I just  related,  tend  to  throw  some  degree 
of  uncertainty  on  their  results.  Dr.  Gallois  repeated  these  ex- 


OF  RESPIRATION. 


239 


periments  publicly  in  my  presence,  and  at  the  society  of  the 
Ecole  de  Medecine  of  Paris.  After  dividing  the  two  nerves  of 
the  eighth  pair  in  a guinea-pig,  and  after  having  by  that  process 
brought  on  a state  of  asphyxia,  he  restored  life  and  motion  to 
the  animal  by  opening  the  trachea  at  its  anterior  part.  The 
blood  of  the  carotids,  which  from  red  had  become  dark  the 
moment  the  nerves  were  divided,  recovers  immediately  its  red 
colour,  the  motion  of  respiration  is  restored,  and  the  animal 
lives  several  days  after  the  experiment.  Whence  does  this 
difference  arise?  Does  the  division  of  the  eighth  pair  bring  on 
asphyxia  by  occasioning  a spasmodic  constriction  of  the  glottis, 
and  by  impeding,  or  even  completely  obstructing  the  admission 
of  the  atmospherical  air? 

LXXVIII.  Of  animal  heat.  The  human  body,  .which  is  habi- 
tually of  a temperature  between  thirty-two  and  thirty-four  de- 
grees of  Reaumur’s  thermometer,  preserves  the  same  degree 
of  warmth  under  the  frozen  climate  of  the  polar  region,  as  well 
as  under  the  burning  atmosphere  of  the  torrid  zone,  during  the 
most  severe  winters  and  the  hottest  summers.  Nay  further,  the 
experiments  of  Blagden  and  Fordyce  in  England,  and  of  Duha- 
mel  and  Tillet  in  France,  show  that  the  human  body  is  capable 
of  enduring  a degree  of  heat  sufficient  to  bake  animal  substances. 
The  Fellows  of  the  Academy  of  Sciences  saw  two  girls  enter 
into  an  oven,  in  which  fruits  and  animal  substances  were  being 
baked;  Reaumur’s  thermometer  which  they  took  in  with  them, 
stood  at  150  degrees;  they  remained  several  minutes  in  the  oven, 
without  suffering  any  inconvenience. 

All  living  bodies  have  a temperature  peculiar  to  themselves, 
and  independent  of  that  of  the  atmosphere.  The  sap  of  plants 
does  not  freeze,  when  the  thermometer  stands  only  at  a few 
degrees  below  zero;  on  placing  the  bulb  of  a thermometer  in  a 
hole  in  the  trunk  of  a tree  during  winter,  the  fluid  sensibly 
rises.  Now,  three  circumstances  remain  to  be  investigated:  in 
the  first  place,  what  produces  in  living  bodies  this  inherent  and 
independent  temperature?  In  the  second  place,  how  do  these 
bodies  resist  the  admission  of  a greater  degree  of  heat  than 
that  which  is  natural  to  them?  What  prevents  caloric,  which  has 
a perpetual  tendency  to  a state  of  equilibrium,  from  passing 
into  a body  surrounded  by  a burning  atmosphere?  Lastly,  how 


240 


OF  RESPIRATION. 


does  a body  which  resists  the  influence  of  heat,  withstand  equal- 
ly the  destructive  influence  of  an^excessive  degree  of  cold. 

LXXIX.  Caloric,  in  a latent  state,  or  in  combination  with 
bodies,  is  disengaged  from  them  whenever  they  assume  a dif- 
ferent state;  when  from  a gaseous  form  they  become  liquid;  or 
when  from  being  liquid  they  become  solid.  Now,  living  bodies 
are  a kind  of  laboratories,  in  which  all  these  changes  are  perpetu- 
ally going  on;  the  blood  which  circulates  in  every  part  of  the 
human  frame,  is  constantly  receiving  supplies  of  fresh  materials; 
from  the  thoracic  duct  which  pours  into  it  the  chyle,  abounding 
in  nutritious  particles;  from  respiration  which  imparts  to  it  an 
aeriform  principle  obtained  from  the  atmosphere;  and  even,  in 
some  cases,  from  cutaneous  absorption,  through  which  difiPerent 
elements  are  /received  into  it.  All  these  different  substances 
carry  along  with  them  into  the  blood  a certain  quantity  of 
caloric,  which  is  combined  with  them,  and  which  is  disengaged 
during  the  changes  which  they  undergo  from  the  influence  of 
the  action  of  the  organs,  and  gives  out  its  caloric  to  the  parts 
among  which  it  is  disengaged.  Of  all  the  principles  in  the  blood, 
which  have  the  power  of  communicating  heat  to  the  organs,  none 
furnishes  a greater  quantity  than  oxygen,  which,  during  respira- 
tion, combines  with  the  blood  in  the  lungs.  Gaseous  substances, 
it  is  well  known,  contain  most  combined  caloric;  their  state 
of  elastic  fluidity  is  entirely  owing  to  the  accumulation  of  that 
principle,  and  they  part  with  it,  when,  from  any  cause  whatever, 
they  become  liquid.  It  is  on  that  account  that  the  heat  of  bo- 
dies is  greater,  the  more  they  have  the  power  of  impregnating 
their  fluids  with  a considerable  quantity  of  oxygen  from  the 
atmosphere.  For  the  same  reason,  as  was  already  observed,  in 
animals  that  have  cellular  lungs,  and  a heart  with  two  ventricles, 
the  blood  is  of  the  same  temperature  as  in  man;  and  such  ani- 
mals belong,  as  well  as  man,  to  the  great  class  of  warm  red- 
blooded  animals;  a class  in  which  birds  occupy  the  first  place, 
from  the  vast  extent  of  their  lungs,  which  reach  into  the  abdo- 
men, and  communicate  with  the  principal  bones  of  the  skeleton. 
The  capacity  of  the  pulmonary  organ  of  birds,  is  aot  the  only 
cause  why  their  temperature  is  eight  or  ten  degrees  higher  than 
that  of  man;  this  increase  of  temperature  depends,  likewise,  on 
the  greater  frequency  of  their  respiration,  and  on  the  velocity  of 


OF  RESPIRATIOI?. 


241 

their  pulse;  on  the  quickness  and  multiplicity  of  their  motions, 
and  on  the  vital  activity  which  animates  them.  In  reptiles  which 
have  vesicular  lungs,  and  a heart  with  a single  ventricle;  whose 
respiration  is  slow,  and  performed  at  distant  intervals,  the  blood, 
though  red,  is  of  very  inferior  temperature  to  that  of  man. 
They  have,  from  that  circumstance,  been  called  cold  red-blooded 
animals;  this  numerous  class  includes  fishes,  which  possess  an 
organ  supplying  but  imperfectly  the  office  of  lungs.  In  fishes  the 
heart,  which  has  but  a single  ventricle,  sends,  it  is  true,  to  the 
gills  (the  organ  supplying  the  place  of  lungs  is  so  called)  the 
whole  of  the  blood;  that  fluid,  however,  is  but  imperfectly  vivi- 
fied in  the  gills,  on  account  of  the  small  quantity  of  air  which 
can  be  taken  in  during  the  act  of  respiration.  Lastly,  in  white- 
blooded  animals  and  in  plants,  the  combinations  with  the  air 
being  more  difficult,  the  vital  energy  less  marked,  the  tempera- 
ture differs  only  by  a few  degrees  from  that  of  the  atmosphere, 
and  they  do  not  endure  heat  or  cold  so  well  as  the  more  perfect 
animals. 

The  lungs,  as  was  before  observed,  consuming  only  a certain 
quantity  of  air,  there  is  no  increase  of  temperature,  however 
great  the  quantity  of  oxygen  contained  in  the  atmosphere  that 
is  breathed;  as  a man  who  should  take  a double  quantity  of 
aliment  could  not  receive  more  nourishment,  than  if  he  content- 
ed himself  with  the  quantity  of  food  proportioned  to  his  wants; 
for,  as  the  digestive  organs  can  extract  only  a certain  quantity 
of  chyle,  the  quantity  of  recrementitious  matter  would  only  be 
greater,  if  more  than  the  due  quantity  of  food  were  received 
into  the  stomach.  Hence  the  common  saying,  that  nourishment 
comes  from  what  we  digest  and  not  from  what  we  eat. 

The  pulmonary  organ  may,  however,  act  on  the  air,  with 
different  degrees  of  power,  in  robbing  it  of  its  oxygen;  and  when 
the  body  becomes  of  an  icy  coldness,  in  certain  nervous  and 
convulsive  affections,  this  cold  may  depend  as  much  on  the  atony 
of  the  lungs,  and  on  the  spasmodic  condition  of  the  chest,  which 
dilating  with  difficulty  does  not  admit  the  air  readily,  as  on  the 
spasm  and  general  insensibility  of  the  organs,  which  all  /w  the 
blood  to  pass  without  affecting  its  component  parts.  If  would  be 
curious  to  ascertain  whether  the  air  expired  from  the  lungs  of  a 
cataleptic,  contains  more  oxygen,  is  less  impaired,  and  contains 

2 H 


242 


OF  RESPIRATION. 


a smaller  quantity  of  carbonic  acid  than  the  breath  of  a sound 
active  adult.  Perhaps  it  would  be  found,  that  in  catalepsy  and 
other  similar  affections,  the  blood  does  not  part  wdth  its  hydro- 
gen and  carbon,  that  it  retains  its  colouring  principles,  and  the 
different  materials  of  the  urine,  which  is  voided  in  a colourless 
and  limpid  state,  insipid  and  without  smell,  and  in  the  condi- 
tion of  a mere  serosity’. 

The  temperature  of  the  body  is  produced  not  only  by  the  pul- 
monary and  circulatory  combinations;  it  is  besides  developed  in 
several  organs,  in  which  fluid  or  gaseous  substances  become 
solid  by  parting  with  a portion  of  their  caloric.  Thus  digestion, 
particularly  of  certain  kinds  of  food,  is  an  abundant  source  of 
caloric;  the  skin  which  is  habitually  in  contact  with  the  atmos- 
phere, decomposes  it  and  deprives  it  of  its  caloric.  Lastly,  ca- 
loric is  produced  and  evolved  in  all  parts,  whose  molecules, 
affected  by  a double  motion,  in  consequence  of  w'hich  they  are 
incessantly  being  formed  and  decomposed,  by  changing  their 
condition  and  consistence,  absorb  or  disengage  more  or  less 
caloric.  The  great  activit}"^  of  the  power  of  assimilation  in  chil- 
dren, is,  no  doubt,  the  cause  of  the  habitually'  high  temperature 
at  that  period  of  life.  The  temperature  of  the  body  is  not  only  one 
or  two  degrees  higher  at  that  period  of  life;  but  young  people, 
after  death,  preserve  for  a longer  period  the  remains  of  vital 
heat;  or  rather,  as  tonicity  does  not  so  soon  forsake  the  capillary 
vessels,  life  departing  reluctantly,  the  combinations  from  which 
caloric  is  evolved,  continue  some  time,  even  after  it  is  extinct. 
For  the  same  reason,  the  bodies  of  persons  that  have  died  sud- 
denly retain  their  warmth  long,  while  an  icy  coldness  seizes  the 
bodies  of  those  who  have  died  of  a lingering  disease,  from  the 
slow,  gradual,  and  total  abolition  of  the  powers  of  life. 

Calorification,  or  the  disengaging  of  animal  heat,  like  nutri- 
tion, takes  place  atall  times,  and  may  be  considered  as  belonging 
to  all  organs.  It  was  of  the  utmost  consequence  that  the  inter- 
nal temperature  of  the  human  body  should  be  nearly'  the  same 
at  all  times.  For,  let  us  for  one  moment  suppose  that  the  tem- 
perature of  the  blood  should  rise  to  fifty'  degrees  of  Reaumur’s 
thermometer,  its  albuminous  parts  would  suddenly  coagulate, 
obstruct  all  the  ji'essels,  interrupt  the  circulation  and  destroy 
life.  When,  therefore,  from  an  increased  activity'  of  the  nutritive 


OF  RESPIRATION. 


243 


combinations,  a greater  quantity  of  heat  is  disengaged,  the  ani- 
mal economy  parts  with  it,  and  is  taken  up  in  a greater  quantity 
by  the  surrounding  bodies.  This  accounts  for  the  equality  of  the 
temperature  of  the  internal  parts  of  the  body  in  old  people  and 
in  children,  notwithstanding  the  difference  of  their  temperature 
externally.  The  difference  consists  in  this:  that  where  most  ca- 
loric is  produced,  most  is  given  out,  and  though  the  blood  and 
urine  in  old  people,  as  well  as  in  the  young,  are  at  thirty-two 
degrees,  what  a difference  is  there  not  between  the  hot  and  pene- 
trating perspiration  which  is  poured  in  abundance  from  the 
child,  and  the  dryness  and  coldness  of  the  skin  in  old  people; 
between  the  sweat  and  warm  breath  of  the  former,  and  the  fro- 
zen breath  of  the  latter!  Hence  the  opinion  so  generally  received 
and  of  such  antiquity,  that  old  people  are  benefited  by  cohabit- 
ing with  the  young.  Thus  we  are  told  that  David  had  a young 
virgin  brought  to  him,  that  he  might  lie  with  her,  and  get  heat 
in  his  limbs  th^t  were  stiffened  with  years. 

If  it  be  true,  that  in  the  very  act  of  nutrition,  which  converts 
our  fluids  into  solids,  there  is  disengaged  a considerable  quan- 
tity of  caloric;  the  motion  of  nutritive  decomposition,  by  which 
our  solids  are  converted  into  liquids,  must  cause  an  equal  quan- 
tity of  heat  to  be  absorbed.  The  objection  is  a very  strong  one, 
and  not  easily  got  over;  it  may  be  answered,  by  observing  that  all 
living  bodies,  from  the  instant  of  their  formation,  contain  a certain 
quantity  of  caloric  which  they  retain,  so  that  this  double  process 
of  acquiring  heat  and  parting  with  it,  the  unavoidable  result  of 
nutritive  composition,  and  decomposition,  merely  keeps  up  an 
equilibrium  and  maintains  the  same  degree  of  temperature. 

The  blood  which  becomes  saturated  with  oxygen,  in  the  ca- 
pillaries of  the  lungs,  parts  with  that  principle,  and  disengages 
its  caloric,  throughout  the  capillary  vessels  of  the  whole  body, 
of  which  each  organ  must  set  free  a greater  quantity,  in  propor- 
tion to  the  activity  of  the  living  principle,  and  to  the  rapidity  of 
the  circulation.  The  parts  through  which  the  greatest  number  of 
vessels  circulate,  perhaps  give  out  most  caloric,  and  communi- 
cate a portion  of  it  to  the  organs,  which  receive  but  a small 
quantity  of  blood,  as  the  bones,  the  cartilages,  &c.  It  is  easy  to 
understand,  why  an  inflamed  part,  through  which  the  blood  cir- 
culates with  more  rapidity,  and  whose  sensibility  and  contrac- 


244 


©F  KESPIRATTON. 


tility  are  much  increased,  is  manifestly  hotter  to  the  feel  of  the 
patient  and  of  the  physician,  though,  as  was  observed  by  John 
Hunter,  a thermometer  applied  to  the  inflamed  part,  shows  a 
scarcely  perceptible  increase  of  temperature.  He  injected  into 
the  rectum  of  a dog,  and  into  the  vagina  of  an  ass,  a strong  so- 
lution of  oxymuriate  of  mercury.  Acute  inflammation  came  on, 
the  swollen  mucous  membrane  formed,  externally,  a considera- 
ble projection.  Blood  flowed  from  the  torn  capillaries,  yet  the 
thermometer  rose  very  slight!}',  only  one  degree  of  Fahrenheit’s. 
But  however  slight  that  increase  of  heat  in  the  inflamed  part, 
it  is  very  sensibly  felt,  on  account  of  the  extreme  sensibility  of 
the  organ,  whose  vital  properties  are  all  increased.  The  liveli- 
ness of  impressions  being  proportionate  to  the  degree  of  the 
power  of  sensation,  one  need  not  wonder  that  the  patient  should 
experience  a sensation  of  burning  heat,  in  a part  in  which  the 
thermometer  indicates  no  increase  of  temperature,  in  which  it 
cannot  be  perceived  even  by  the  touch.  I have  just  felt  a young 
man’s  hand  that  is  swollen  from  chilblains;  though  the  pain 
which  he  feels  in  it  seems  to  him  to  be  occasioned  by  an  accumu- 
lation of  caloric,  his  hand  is  colder  than  mine,  which  is  of  the 
same  degree  of  warmth  as  the  rest  of  my  body,  and  in  which 
I have  no  peculiar  sensation.  It  may,  therefore,  be  laid  down  as 
an  axiom,  that  the  real  or  thermometrical  increase  of  heat  is  in- 
considerable in  inflammation,  but  that  is  intensely  felt,  in  con- 
sequence of  the  increase  of  sensibility. 

What  is  the  reason,  that  during  the  cold  fit  of  a febrile 
paroxysm,  a sensation  of  excessive  cold  is  felt  in  a part  in  which 
no  diminution  of  heat  can  be  discovered  by  the  touch?  Whence 
comes  the  burning  heat  which  attends  inflammatory  fever 
(causos^P  What  is  the  cause  ot  the  difference  of  the  sensations 
attending  the  heat  of  erysipelas,  bilious  fevers  and  phlegmon, 
&c.?  These  various  sensations  are  owing  to  the  different  modi- 
fications of  sensibility  In  these  different  diseases.  Should  this  ex- 
planation appear  unsatisfactory,  let  it  be  recollected,  that  how- 
ever accurate  the  calculations  may  be,  that  have  been  made  on 
the  subject  of  caloric  or  of  the  matter  of  heat,  the  existence  of 
■caloric  itself  is  hypothetical,  and  that  it  is  not  known,  whether 
caloric  is  a body,  or  whether  heat  is  merely  a property  of  matter. 

LXXX.  If  we  now  inquire  into  the  causes  which  enable  the 


OP  RESPIRATION. 


245 

body  to  resist  the  admission  of  a degree  of  heat  superior  to  that 
which  habitually  belongs  to  it,  we  shall  be  compelled  to  admit, 
in  all  living  bodies,  a power  by  means  of  which  they  repel  an  ex- 
cess of  heat,  and  retain  the  same  temperature.  Cutaneous  perspi- 
ration, it  is  true,  acts  very  powerfully  in  lowering  the  tempera- 
ture, and  as  this  evaporation  increases  with  the  temperature,  it 
should  seem  as  if  this  function  sufficed  to  moderate  the  heat  of 
the  body,  and  to  restore  the  equilibrium. 

It  is  a fact  known  since  the  time  of  Cullen,*  that  the  evapo- 
ration of  fluids,  or  their  solution  in  the  air,  is  the  most  powerful 
means  of  cooling  bodies,  and  that  the  mercury  in  the  bulb  of  a 
thermometer,  may  be  frozen  merely  by  moistening  it  with  aether, 
spirits  of  wine,  or  any  other  volatile  substance,  and  then  expos- 
ing it  to  a dry  and  warm  air.  This  method  is  equally  successful 
in  its  application  to  the  human  body,  and  the  hands  may  be 
cooled  to  such  a degree  as  to  feel  benumbed,  by  being  frequently 
wetted  with  a spirituous  fluid,  and  by  being  moved  in  a dry  and 
renewed  air.  But  though  cutaneous  perspiration  operates  in  a 
somewhat  similar  manner,  and  though  it  may  be  ranked  among 
the  means  which  nature  employs  to  preserve  the  animal  tem- 
perature in  a nearly  uniform  state,  it  must  however  be  confess- 
ed, that  it  is  not  the  only  way  in  which  this  object  is  accomplish- 
ed, and  that  it  does  not  satisfactorily  account  for  this  phenome- 
non, for,  the  evaporation  of  the  fluids  contained  in  dead  animal 
substances,  does  not  prevent  their  being  roasted  on  the  applica- 
tion of  heat;  and  besides,  fishes  and  frogs  have  been  known  to 
live  and  retain  their  temperature  in  mineral  waters,  nearly  of  a 
boiling  heat.f 

I thought  it  right  to  repeat  these  experiments,  and  with  this 
view,  I placed  living  frogs  in  a vessel  containing  water  at  fifty 
degrees  of  temperature,  and  on  taking  them  out,  at  the  end  of 
ten  minutes,  I ascertained  that  they  were  not  so  hot  as  the 
liquid,  nor  as  pieces  of  flesh  which  had  been  put  into  it  at  the 
same  time. 

* This  celebrated  physician  made  this  discovery  about  forty  years  ago,  which 
has  thrown  much  light  on  several  physico-chemical  phenomena,  and  he  pub- 
lished it  in  a dissertation  entitled;  “ Of  the  cold  produced  by  evaporating 
fluids,  and  of  some  other  means  of  producing  cold,  by  Dr.  W.  Cullen.” 

t See  Sonnerafs  Voyage  to  the  East  Indies. 


246 


OF  RESPIRATION. 


We  cannot  admit  the  opinion  of  Grimaud,  that  living  bodies 
have  the  power  of  producing  cold;  for,  as  cold  is  merely  the  ab- 
sence of  heat,  one  cannot  allow  a positive  existence  to  a nega- 
tive being. 

Habit  has  a remarkable  influence  on  the  faculty  which  the 
body  possesses  of  bearing  a degree  of  heat,  much  exceeding  that 
which  is  natural  to  it.  Cooks  handle  burning  coals  with  impu- 
nity; workmen  employed  in  forges,  leave  the  mark  of  their  feet 
on  the  burning  and  liquid  metal,  at  the  moment  when  it  becomes 
solid  by  cooling.  Many,  no  doubt,  recollect  the  too  famous  in- 
stance of  a Spaniard,  who  became  so  general  a subject  of  con- 
versation in  Paris:  this  young  man,  in  making  his  way  through 
a house  on  fire,  perceived  that  the  heat  was  less  inconvenient  to 
him  than  he  had  imagined.  He  applied  himself  to  bear,  with  im- 
punity the  action  of  fire,  and  was  enabled  to  apply  to  his  tongue 
a spatula  heated  red  hot,  and  to  apply  the  soles  of  his  feet  and 
the  palms  of  his  hand  on  a red  hot  iron,  or  on  the  surface  of 
boiling  oil.  Nothing  can  equal  the  absurdity  and  the  exaggera- 
tion of  the  stories  that  were  told  of  this  man,  except  the  igno- 
rance and  the  want  of  veracity  of  those  who  invented  them. — 
The  following  is  a correct  statement  of  the  feats  of  this  man,  who 
was  represented  as  incombustible  and  insensible.  He  passes 
rapidly  along  the  surface  of  his  tongue,  which  is  covered  with 
saliva,  a red  hot  spatula,  the  action  of  which  seems  merely  to 
dry  it,  by  bringing  on  an  evaporation  of  the  fluids  with  which 
it  is  covered.  After  carrying  the  spatula  from  the  base  to  the  tip 
of  his  tongue,  he  brings  it  back  again  into  his  mouth,  and  applies 
it  to  his  palate,  to  which  it  communicates  a part  of  its  heat,  at 
the  same  time  that  it  becomes  moistened  with  saliva.  This  man 
having,  in  a public  exhibition,  carried  on,  too  long,  the  applica- 
tion of  the  spatula,  the  caustic  eflects  of  its  heat  showed  them- 
selves, the  epidermis  was  detached,  and  found  coiled,  like  the 
outer  covering  of  an  onion,  in  the  cloth  which  he  used  to  wipe 
his  mouth.  He  does  not  dip  his  hands  and  feet  in  boiling  oil,  he 
merely  applies  to  the  surface  of  the  fluid  his  palms  and  his  soles, 
and  he  repeats  this  frequently,  with  only  a short  interval  be- 
tween each  application.  When  the  experiment  is  carried  on  for 
a certain  length  of  time,  there  is  emitted  a smell  of  burnt  horn. 
No  one  has  yet  observed,  that  though  this  man’s  hands  are  not 


OP  RESPIRATION'. 


247 

callous,  the  palms  of  these,  and  the  soles  of  his  feet  are  cushion- 
ed with  fat.  A thick  layer  of  fat,  which  is  a bad  conductor  of 
heat,  separates  the  skin  from  the  subjacent  aponeuroses  and 
nerves;  this  circumstance,  to  a certain  degree,  accounts  for  his 
imperfect  sensibility. 

His  pulse,  during  those  experiments,  was  about  a hundred 
and  twenty;  the  perspiration  evidently  increased,  and  some- 
times copious.  Every  part  of  his  body  possesses  the  ordinary 
degree  of  sensibility,  may  be  destroyed  by  the  protracted  appli- 
cation of  caustic  substances,  and  would  be  consumed  by  fire,  if 
applied  for  a sufficient  length  of  time,  and  nitric  acid  would  in- 
fallibly destroy  his  tongue  if  he  took  any  into  his  mouth,  as  it 
has  been  said  he  did.  This  man,  therefore,  in  no  one  respect  de- 
parts from  the  known  laws  of  the  animal  economy,  but,  on  the 
contrary,  affords  an  additional  proof  of  the  influence  of  habit  on 
our  organs. 

LXXXI.  Before  bringing  to  a conclusion  this  article  on  ani- 
mal heat,  it  remains  for  me  to  explain  how  the  body  resists 
cold,  and  preserves  its  temperature,  in  the  midst  of  a frozen 
atmosphere.  This  cannot  be  accomplished  without  an  increase 
of  activity  in  the  organs;  it  is  only  by  augmenting  the  sum  of 
the  combinations  by  which  caloric  is  disengaged,  that  we  can 
succeed  in  making  up  for  the  loss  of  that  principle  so  necessary 
to  our  existence. — What  is  the  reason  that  in  cold  weather,  di- 
gestion is  more  actiye  (^Hieme  verb  ventres  sunt  calidiores, 
Hipp.),  the  pulse  stronger  and  more  frequent,  and  the  vital 
energy  greater?  It  is  because  heat  comes  from  the  same  source, 
and  is  produced  by  the  same  mechanism  as  the  nutrition  of  the 
organs;  and  that  its  evolution  may  go  on  increasing,  it  is  neces- 
sary that  the  secretions,  nutrition,  in  a word,  all  the  vital  func- 
tions, should  increase  in  the  same  proportion. 

Observe,  for  a moment,  a man  who  is  exposed  to  a moderate 
degree  of  cold,  he  feels  more  activity,  more  strength,  and  is 
more  nimble,  he  walks  and  exerts  himself,  the  most  violent 
exertions  do  not  appear  to  him  laborious,  he  struggles  against 
the  disadvantages  of  the  debilitating  influence;  and  provided 
the  cold  is  not  excessive  and  the  body  tolerably  vigorous,  there 
is  disengaged,  within  himself,  a sufficient  quantity  of  caloric 
to  make  up  for  the  loss  of  that  which  is  carried  off  by  the  air 


OF  RESPIRATION. 


248 

and  the  surrounding  bodies.  These  general  effects  of  cold  are 
not  disproved  by  what  happens,  when  only  a part  of  the  body 
is  exposed  to  it.  Supposing  the  temperature  a few  degrees  below 
zero,  there  is  felt,  at  first,  a sensation  of  cold  much  more  in- 
convenient, cseteris  paribus,  than  if  it  acted  on  a more  extensive 
surface.  The  spot  on  which  the  cold  air  acts,  becomes  affected 
with  a painful  sense  of  pricking,  reddens,  then  inflames;  and  in 
this  case,  inflammation  is  evidently  the  result  of  a salutary  effort 
of  nature,  which  determines  into  the  inflamed  part  an  excess  of 
the  vital  principle,  so  that  the  quantity  of  heat  that  is  disengag- 
ed may  correspond  to  that  which  has  been  abstracted.  The  effort 
of  this  conservatory  principle  is  more  marked,  than  if  the  whole 
surface  of  the  body  were  at  once  exposed  to  cold,  because,  act- 
ing wholly  on  a limited  point,  of  small  extent,  it  operates  with 
more  intensity. 

Beyond  a certain  degree,  however,  nature  in  vain  struggles 
against  cold;  if  severe,  and  if  the  creature  exposed  to  it  have 
not  the  power  of  sufficient  reaction,  the  part  becomes  purple 
and  benumbed  from  the  loss  of  its  caloric,  vitality  ceases,  and 
it  mortifies;  and  if  the  whole  body  is  equally  exposed  to  the 
influence  of  cold,  the  person  is  benumbed,  feels  a stiffening  of 
his  limbs,  stammers,  and  overpowered  by  an  irresistible  propen- 
sity, yields  to  a sleep  which  inevitably  ends  in  death.  By  yielding 
thus  to  the  illusive  sweets  of  a perfidious  sleep,  many  travellers 
have  perished  after  losing  their  way,  in  the  mountains  of  the 
old  and  of  the  new  world.  Thus,  two  thousand  soldiers  of 
Charles  the  twelfth’s  army  perished,  during  a siege,  in  the 
severe  winter  of  ITOQ. 

To  resist  the  effects  of  cold,  a certain  degree  of  strength  and 
vigour  is  therefore  necessary;  it  is  consequently  very  injudicious 
to  recommend  the  cold  bath  to  very  young  children,  to  deli- 
cate and  nervous  women,  to  persons  whose  constitution  is  not 
capable  of  a sufficient  reaction.  The  evil  attending  the  injudi- 
cious use  of  this  remedy  in  the  cases  that  have  just  been  enu- 
merated, justifies  the  apparently  singular  terms  in  which  Galen 
expressed  himself:  “Let  the  Germans  (says  this  first  of  physio- 
logists) let  the  Sarmatians,  those  northern  nations  as  barbarous 
as  bears  and  lions,  plunge  their  children  in  frozen  water;  what 
I write  is  not  intended  for  them.” 


OF  RESPIRATION. 


249 

On  the  other  hand,  if  it  be  recollected,  that  there  is  within 
us  a power  of  reaction  which  increases  with  use,  that  motion 
strengthens  our  organs,  it  will  be  readily  understood,  that  cold 
acts  as  a tonic,  whenever  it  is  not  applied  to  such  a degree  as  to 
extinguish  the  vital  power. 

The  manner  in  which  enlightened  physicians  have,  at  all 
times,  prescribed  the  cold  bath,  shows  that  they  were  acquaint- 
ed with  this  tonic  effect  depending,  not  on  the  application  of 
cold,  which  in  itself  is  debilitating,  but  on  the  reaction  which  it 
occasions.  Hence  along  with  the  cold  bath,  they  are  in  the 
habit  of  recommending  exercise,  a generous  wine,  bark,  nutri- 
tious food,  and  an  analeptic  regimen,  calculated  to  excite  a salu- 
tary reaction. 

LXXXII.  Animal  heat  is,  therefore,  produced  by  the  com- 
binations of  our  fluids  and  solids  in  the  process  of  nutrition;  it 
is  a function  common  to  all  the  organs,  for,  as  they  all  nourish 
themselves,  so  they  all  disengage,  more  or  less,  the  caloric 
combined  with  the  substances  which  they  apply  to  their  nutri- 
tion. 

Though  we  are  without  precise  information  respecting  the 
manner  in  which  a living  body  resists  the  admission  of  a degree 
of  heat  exceeding  that  which  is  natural  to  it,  one  may  consider 
cutaneous  exhalation,  which  is  increased  by  the  use  of  heating 
substances,  as  the  most  powerful  means  employed  by  nature  to 
get  rid  of  the  excess  of  heat,  and  to  restore  the  equilibrium. 

Lastly,  the  body  resists  cold,  because  the  organs  being  ren- 
dered more  active  by  cold,  there  is  disengaged  a quantity  of 
caloric  equal  to  that  which  is  carried  off  by  the  air,  or  by  the 
other  substances  with  which  the  body  happens  to  be  in  contact. 

LXXXIII.  The  rapidity  of  the  circulation  of  the  blood 
through  the  lungs,  is  equal  to  the  velocity  with  which  it  flows 
in  the  other  organs.  For,  if  on  the  one  hand,  the  parietes  of 
the  right  ventricle  and  of  the  pulmonary  artery,  are  weaker  and 
thinner  than  those  of  the  left  ventricle  and  aorta,  the  lungs,  from 
their  soft,  easily  dilated,  and  spungy  texture,  are  the  most  easily 
penetrated  by  the  fluids  of  all  our  organs. 

The  right  ventricle  sends  into  the  lungs  a quantity  of  blood, 
equal  to  that  which  each  contraction  of  the  left  ventricle  propels 

2 I 


250 


OF  RESPIRATION. 


into  the  aorta;  and  it  is  not  necessary  to  adopt  the  opinion  of 
M.  Kruger,  that  each  contraction  of  the  heart  sends  into  the 
lungs  and  into  the  rest  of  the  body  an  equal  quantity  of  blood; 
for,  in  that  case,  the  circulation  would  have  been  much  slower, 
the  length  of  the  lungs  being  much  shorter  than  the  whole  body. 
Nor  need  we  say,  with  Boerhaave,  that  this  circulation  is  much 
more  rapid,  because  the  same  quantity  of  blood  returns  by  the 
extremities  of  the  pulmonary  artery,  and  of  all  the  other  arteries 
of  the  body. 

The  extension  of  the  pulmonary  tissue,  the  straightening  of  its 
vessels  are,  no  doubt,  favourable  to  the  circulation  of  the  blood; 
but  if  the  admission  of  air  did  not  answer  a different  purpose, 
the  circulation  would  not  be  indispensably  necessary.  The  blood 
flows  from  the  right  into  the  left  cavities  of  the  heart,  notwith- 
standing the  collapse  of  the  lungs  and  the  creases  of  their  ves- 
sels. The  air  which  penetrates,  at  all  times,  into  the  lungs, 
supports  their  tissue  and  the  vessels  which  are  distributed  to 
it,  so  that  even  during  expiration,  the  vessels  are  much  less 
creased  than  has  been  imagined  by  several  physiologists.  But 
the,  changes  produced  by  the  contact  of  the  atmosphere,  renovate 
this  fluid,  and  fit  it  to  re-excite  and  keep  up  the  action  of  all  the 
organs  which  require  to  be  stimulated  by  arterial  blood.  If  you 
make  a living  animal  breathe  de-oxygenated  air,  the  blood  un- 
dergoes no  change  by  its  pulmonary  circulation;  the  left  cavities 
of  the  heart  are  no  longer  duly  irritated  by  this  fluid,  which 
preserves  all  its  venous  qualities;  their  action  becomes  languid, 
and  with  it  that  of  all  the  organs;  and  in  a little  while,  it  ceases 
altogether.  It  is  revived  by  introducing  pure  air,  through  a 
tube  fitted  to  the  trachea;  all  the  parts  seem  to  awake  out  of  a 
sort  of  lethargic  sleep:  in  which  they  are  again  immersed,  by 
depriving  the  lungs  anew  of  the  vital  air. 

The  chyle,  mixed  in  great  quantity  with  the  venous  blood, 
undergoes,  in  its  passage  through  the  heart  and  the  sanguineous 
system,  a more  violent  agitation:  its  molecules  are  struck  together, 
break  on  each  other,  and,  thus  attenuated,  become  more  per- 
fectly intermingled:  in  its  passage  through  the  lungs,  a great 
part  of  this  recrementitious  fluid  is  deposited  by  a sort  of  inter- 
nal perspiration,  in  the  parenchymatous  substance  of  these  vis- 


OF  RESPIRATION. 


251 


cera.  Oxydated  by  the  contact  of  the  air,  re-absorbed  by  a 
multitude  of  inhalent  vessels,  it  is  carried  into  the  bronchial 
glands,  which  are  found  blackened  by  what  it  there  deposits  of 
carbonic  and  fuliginous  matter.  Purified  by  this  elaboration,  it 
returns  into  the  thoracic  duct,  which  pours  it  into  the  subclavian 
vein,  whence  it  soon  returns  to  the  lungs,  to  be  there  anew  sub- 
jected to  the  action  of  the  atmosphere;  so  that  there  is  effected, 
through  these  organs,  a real  lymphatic  circulation,  of  which  the 
object  is  to  bring  on  the  chyle  to  a higher  degree  of  animaliza- 
tion. 

LXXXIV.  Of  pulmonary  exhalation.  It  will  be  remembered, 
that  one  of  the  great  differences  between  the  blood  of  the  arte- 
ries, and  that  of  the  veins,  consists  in  the  great  quantity  of  se- 
rum found  in  this  last.  It  is  in  the  lungs,  that  the  separation  of 
this  aqueous  part  takes  place,  and  that  its  proportion  is  reduced, 
whether  it  be,  that  oxygen  gives  albumen  and  gelatine  a greater 
tendency  to  concrete,  or  that  the  serum,  formed  by  the  fixation 
of  oxygen  throughout  the  whole  extent  of  the  circulatory  system, 
exhales  from  the  arteries,  and  thus  furnishes  the  matter  of  pul- 
monary exhalation.  It  is  scarcely  possible  to  admit  the  combi- 
nation of  oxygen  with  the  hydrogen  of  the  venous  blood,  and 
that  water  is  thus  formed  from  its  element,  as  happens  when 
storms  are  gathering  in  the  high  regions  of  the  atmosphere.  If 
a similar  process  can  be  carried  on  in  the  lungs,  without  pro- 
ducing deflagration  and  the  various  phenomena  attending  the 
production  of  aqueous  meteors,  it  is  probable,  that  it  furnishes 
but  a small  part  of  the  exhalation;  and  that  this  humour,  analo- 
gous to  the  serum  of  the  blood,  exhales,  completely  formed, 
from  the  arterial  capillaries  ramified  in  the  branchiae  and  the 
lobular  tissue  of  the  lungs.  It  is  believed,  that  the  quantity  of 
the  pulmonary  exhalation  is  equal  to  that  of  the  cutaneous  ex- 
halation (four  pounds  in  twenty-four  hours).  These  two  secre- 
tions are  supplemental  to  one  another:  when  much  water  passes 
off  by  the  pulmonary  exhalation,  the  cutaneous  is  less,  and  vice 
versa. 

The  surface,  from  which  the  pulmonary  exhalation  is  given 
out,  is  equal,  if  not  superior  in  extent  to  that  of  the  skin;  exha- 
lation and  absorption  are  at  once  carried  on  from  that  surface, 
many  nerves  are  distributed  So  it,  and  are  almost  exposed  in  the 


OF  RESPIRATION. 


252 

tissue  of  the  membranes  which  are  extremely  thin.  Are  the  mi- 
asmata with  which  the  atmosphere  is  sometimes  loaded,  absorb- 
ed by  the  lymphatics,  which,  it  is  well  known,  have  the  power  of 
taking  up  gaseous  substances;  or  do  they  merely  produce  on  the 
nervous  and  sensible  membranes  of  the  bronchise,  and  of  the 
lobular  tissue,  the  impression  whence  the  diseases  of  which  they 
are  the  germ  arise? 

A part  of  the  caloric  which  is  disengaged  in  the  combinations 
which  oxygen  undergoes  in  the  lungs,  is  taken  up  in  dissolving 
and  reducing  into  vapour  the  pulmonary  exhalation,  which  is  the 
more  abundant,  according  as  respiration  is  more  complete.  Pul- 
monary exhalation  should  be  carefully  distinguished  from  the 
mucous  matter  secreted  within  the  bronchiae  and  trachea,  and 
which  is  thrown  up  by  a forcible  expiration,  and  forms  the  mat- 
ter of  what  we  spit. 

LXXXV.  Of  asphyxia.  The  term  asphyxia,  though  merely 
indicating  a want  of  pulse,  is  applied  to  any  kind  of  apparent 
death  occasioned  by  an  external  cause  and  suspending  respira- 
tion, as  submersion,  strangulation,  tbe  diminution  of  oxygen  in 
the  air  inhaled,  &c.  The  only  difference  between  real  death, 
and  asphy’xia,  is,  that  in  this  last  state  the  principle  of  life  may 
yet  be  re-animated,  whilst,  in  the  other,  it  is  completely  extinct. 

Asphyxia  takes  place  in  drowning,  because  the  lungs,  de- 
prived of  air,  no  longer  impart  to  the  blood  which  passes 
through  them,  the  qualities  essential  to  the  support  of  life. 

The  water  does  not  find  its  way  into  these  viscera:  the  spas- 
modic closing  of  the  glottis  prevents  its  getting  into  the  trachea 
and  its  branches.  Yet  there  is  found  a small  quantity  in  the 
bronchiae,  after  drowning,  always  frothy,  because  air  has  mixed 
with  it,  in  the  struggles  which  precede  asphyxia.  If  the  body  re- 
main long  under  water,  the  spasmodic  state  of  the  glottis  ceases, 
water  passes  into  the  trachea  and  fills  the  lungs.  The  anatomical 
examination  of  a drowned  body,  shows  the  lungs  collapsed,  and 
in  the  state  of  expiration;  the  right  cavities  of  the  heart,  the  ve- 
nous trunks  which  terminate  in  them,  and  generally,  all  the 
veins,  are  gorged  with  blood,*  whilst  the  left  cavities  and  the 

* Hence  the  dark  and  livid  colour  of  the  skin  and  conjunctiva.  This  last 
membrane  is  frequently  injected  with  dark  blood;  the  very  delicate  veins  of 
the  brain  are  considerably  dilated,  and  this  viscus  is  distended  with  venous 
blood . 


OF  RESPIRATION. 


25S 


arteries  are  almost  entirely  empty.  Life  ceases  in  this  kind  of 
asphyxia,  because  the  heart  has  sent  to  the  different  organs,  and 
especially  to  the  lungs,  no  blood  that  is  not  deficient  in  qua- 
lities necessary  to  their  action;  and  perhaps  also,  because  the 
venous  blood  that  is  accumulated  in  the  tissues,  affects  them  by 
its  oppressive  and  deadly  influence.  On  that  account,  the  best 
way  of  restoring  the  drowned  to  life,  is  to  blow  pure  air  into 
their  lungs.  This  is  done  by  means  of  bellows  adapted  to  a ca- 
nula  introduced  into  the  nostril;  if  a proper  apparatus  cannot  be 
procured,  one  might  blow  with  one’s  mouth  into  that  of  the 
drowned  person,  or  into  his  nostrils,  by  means  of  a tube;  but  air 
so  expired,  having  already  undergone  the  process  of  respiration, 
contains  a much  smaller  quantity  of  oxygen,  and  is  much  less 
fitted  to  excite  the  action  of  the  heart.  There  remain  several 
other  less  efficacious  remedies,  such  as  friction,  bronchotomy, 
glysters,  fumigations  and  suppositories,  stimulating  errhines, 
and  especially  ammonia;  stimulants  taken  into  the  mouth  and 
stomach,  the  application  of  fire,  bleeding,  the  bath,  electricity, 
and  galvanism. 

The  redness  and  lividity  of  the  face,  in  persons  who  are 
hanged,  had  led  to  the  opinion  that  death,  in  such  cases,  was 
from  apoplexy;  but  it  appears  that  in  the  asphyxia  from  stran- 
gulation, as  in  that  from  drowning,  death  is  caused  by  the  inter- 
ception of  the  air.  To  prove  this,  Gregory  performed  the  follow- 
ing experiment;  he  opened  the  trachea  of  a dog,  and  passed  a 
noose  round  his  neck,  below  the  wound.  The  animal,  though 
hanged,  continued  to  live  and  to  breathe;  the  air  entered  and 
came  out  alternately  at  the  small  opening.  He  died,  when  the  con- 
striction was  applied  below  the  wound.  A respectable  surgeon, 
who  served  in  the  Austrian  army,  assured  me,  that  he  had  saved 
the  life  of  a soldier,  by  performing  upon  him  the  operation  of 
laryngotomy,  a few  hours  before  his  execution. 

Persons  who  are  hanged  may  die,  however,  from  dislocation 
of  the  cervical  vertebrae,  and  from  the  injury  done,  at  the  same 
time,  to  the  spinal  marrow.  Louis,  it  is  well  known,  ascertained, 
that  ofthe  two  executioners  in  Lyons  and  Paris, the  one  dispatch- 
ed the  criminals  he  executed,  by  dislocating  the  head  at  its  arti- 
culation with  the  neck,  while  the  other  executioner  destroyed 
them  by  inducing  asphyxia. 


254 


OF  RESPIRATION. 


Of  the  different  mephitic  gases  unfit  for  respiration,  some  ap- 
pear to  bring  on  asphyxia,  merely  by  depriving  the  lungs  of  the 
vital  air  necessary  to  the  support  of  life,  while  others  evidently 
affect  the  organs  and  the  blood  which  fills  them, by  their  poison- 
ous and  deleterious  influence. 

One  may  mention  among  the  former,  carbonic  acid.  In  the 
asphyxia  occasioned  by  this  gas,  and  which  of  all  others  is  the 
most  frequent,  the  blood  preserves  its  fluidity,  the  limbs  their 
suppleness,  and  the  body  its  natural  warmth,  or  even  a greater 
degree  of  warmth,  for  some  hours  after  death;  for,  this  kind  of 
asphyxia  occurring  always  in  a very  hot  situation,  the  body,  de- 
prived of  life,  admits  an  excess  of  caloric,  such  as  would  have 
been  resisted  if  the  vital  power  had  not  been  suspended.  How- 
ever, in  this  asphyxia,  as  in  the  preceding,  the  lungs  remain  un- 
injured; the  right  cavities  of  the  heart  and  the  venous  system, 
are  gorged  with  a dark  but  fluid  blood.  In  the  asphyxia,  on  the 
other  hand,  that  is  occasioned  by  sulphuretted  or  phosphuretted 
hydrogen,  &c.  or  by  certain  vapours  whose  nature  is  not  well  un- 
derstood, and  which  escape  from  privies,  or  from  vaults  in 
which  a number  of  dead  bodies  undergo  putrefaction;  there  ar» 
frequently  found  in  the  lungs,  dark  and  gangrenous  marks,  and 
death  seems  the  effect  of  a poison  which  is  the  more  active,  as  its 
particles,  exceedingly  divided  and  in  a gaseous  state,  are  more  in- 
sinuating, and  affect  throughout  its  whole  extent  the  nervous  and 
sensible  surface  of  the  lungs.* 

Inebriation  seldom  goes  the  length  of  bringing  on  asphyxia,  it 
most  commonly  produces  a stupor  readily  distinguished  from 

* The  celebrated  Mr.  Goodwin,  not  to  mention  others,  concurs  with  our 
author,  in  the  opinion  that  the  carbonic  acid  destroys  life,  and  produces  its 
lesser  mischievous  effects  merely  by  the  preclusion  of  oxygen.  These  writers 
however,  are  undoubtedly  mistaken.  Nothing  is  more  clear  than  that  this 
species  of  gas  has  a positive  operation  on  the  animal  economy.  We  will  state 
a few  facts  in  proof  of  it. 

1.  It  has  been  shown,  that  animals  die  much  sooner  when  exposed  to  the 
carbonic  acid,  than  when  placed  in  vacuo,  or  when  a ligature  is  applied  to  Uie 
trachea. 

2.  It  has  been  shown,  that  frogs  may  be  kept,  without  injury,  for  upwards  of 
an  hour  under  water,  but  perish  almost  instantly  if  put  into  an  atmosphere  of 
fixed  air. 

3.  It  has  been  shown,  that  when  the  carbonic  acid  is  combined  with  water 
it  very  speedily  destroys  fish. — Ed. 


OF  RESPIRATION. 


25S 

the  affection  treated  of  in  this  article,  by  the  perceptible,  though 
obscure  pulse,  and  by  the  motions  of  respiration,  though  these 
are  rare  and  indistinct.  On  this  account,  M.  Pinel,  in  his  Noso- 
graphie  phihsophique^  has  placed  inebriation  and  the  different 
kinds  of  asphyxia,  in  two  separate  genera  of  the  class  neuroses. 
It  is  conceivable,  however,  that  the  muscular  irritability  may  be 
so  far  impaired  by  the  use  of  spirituous  liquors,  that  the  heart 
and  diaphragm  might  lose  the  power  of  contraction,  which  would 
brings  on  complete  asphyxia. 

The  glottis,  through  which  the  atmospherical  air  passes  in 
its  way  to  the  lungs,  is  so  small,  that  it  may  be  readily  ob- 
structed, when  the  epiglottis  rising  at  the  moment  of  deglutition, 
the  substance  that  is  swallowed  stops  at  the  orifice  of  the  larynx; 
a grape  seed  may  produce  this  effect,  and  it  was  in  this  manned, 
#e  are  told,  that  Anacreon,  that  lovely  poet  of  the  graces  and 
of  voluptuousness,  came  by  his  death.  Gilbert,  the  poet,  died  in 
the  same  way,  after  a long  and  painful  agony.  A great  eater,  ill 
the  midst  of  a feast,  went  into  an  adjoining  room,  and  did  not 
return,  to  the  great  surprise  of  all  the  guests.  He  was  found 
stretched  on  the  floor,  without  any  sign  of  life.  Help,  given  by 
ignorant  people,  was  of  no  use.  On  opening  the  body,  a piece  of 
mutton  was  found  fixed  in  the  larynx,  and  completely  stopping 
the  passage  of  the  air. 

Sometimes  a child  is  born  and  shows  no  signs  of  life.  When 
it  is  probable,  from  the  circumstances  of  the  delivery,  that  there 
has  been  no  organic  injury  decidedly  mortal,  it  must  be  consi- 
dered as  a case  of  asphyxia  from  weakness;  and  all  means  em- 
ployed that  are  recommended  in  such  cases,  especially  blowing 
in  air  into  the  lungs,  by  means  of  a tube  introduced  into  the 
mouth  or  nostrils.  It  is  thus,  that  the  Prophet  Elisha  restored  to 
life  the  son  of  the  Shunammite,  as  we  are  informed  in  the 
second  book  of  Kings,  chapter  the  fourth. 

LXXXVI.  Of  certain  phenomena  of  respiration^  as  sighing^ 
sobbing,  yawning,  sneezing,  coughing,  hiccup,  laughing,  £s?c. 
When  the  imagination  is  strongly  impressed  with  any  object, 
when  the  vital  functions  are  languid,  the  vital  principle  seems  to 
forsake  all  the  organs,  to  concentrate  itself  on  those  which  par- 
take most  in  the  affection  of  the  mind.  When  a lover,  in  the 
midst  of  an  agreeable  reverie,  sighs  deeply,  and  at  intervals,  a 


256 


OF  RESPIRATION. 


physiologist  perceives  in  that  expression  of  desire,  nothing  but 
a long  and  deep  inspiration,  which,  by  fully  distending  the  lungs, 
enables  the  blood,  collected  in  the  right  cavities  of  the  heart,  to 
flow  readily  into  the  left  cavities  of  that  organ.  This  deep  inspi. 
ration,  which  is  frequently  accompanied  by  groans,  becomes  ne- 
cessary, as  the  motions  of  respiration  rendered  progressively 
slower,  are  no  longer  sufficient  to  dilate  the  pulmonary  tissue. 

Sobbing  differs  from  sighing  merely  in  this,  that  though  the 
expiration  is  long,  it  is  interrupted,  that  is,  divided  into  distinct 
periods. 

Yawning  is  effected  in  the  same  manner;  it  is  the  certain  sign 
of  ennui,  a disagreeable  affection,  which,  to  use  the  expression 
of  Brown,  may  be  considered  as  debilitating  or  asthenic.  The 
fatigued  inspiratory  muscles  have  some  difficulty  in  dilating  the 
chest;  the  contracted  lungs  are  not  easily  penetrated  by  the 
blood,  which  stagnates  in  the  right  cavities  of  the  heart,  and 
produces  an  uneasy  sensation,  which  is  put  an  end  to  by  a long 
and  deep  inspiration;  the  admission  of  a considerable  quantity 
of  air  is  facilitated  by  opening  the  mouth  widely  by  the  separa- 
tion of  both  jaws.  One  yawns  at  the  approach  of  sleep,  because 
the  agents  of  inspiration,  being  gradually  debilitated,  require  to 
be  roused  at  intervals.  One  is  likewise  apt  to  yawn  on  waking, 
that  the  muscles  of  the  chest  may  be  set  for  respiration,  which 
is  always  slower  and  deeper  during  sleep.  It  is  for  the  same 
reason,  that  all  animals  yawn  on  waking,  that  the  muscles  may 
be  prepared  for  the  contractions  which  the  motions  of  respira- 
tion require.  The  crowing  of  the  cock  and  the  flapping  of  his 
wings  seem  to  answer  the  same  purpose.  It  is  in  consequence  of 
the  same  necessity,  that  the  numerous  tribes  of  birds  in  our 
groves,  on  the  rising  of  the  sun,  warble,  and  fill  the  air  with 
harmonious  sounds.  A poet  then  fancies  he  hears  the  joyous 
hymn,  by  which  the  feathered  throngs  greet  the  return  of  the 
god  of  light. 

While  gaping  lasts,  the  perception  of  sounds  is  less  distinct, 
the  air,  as  it  enters  the  mouth,  rushes  along  the  Eustachian  tubes 
into  the  tympanum,  and  the  membrane  is  acted  upon  in  a dif- 
ferent direction.  The  recollection  of  the  relief  attending  the 
deep  inspiration  which  constitutes  gaping,  the  recollection  of 
the  grateful  sensation  which  follows  the  oppression  that  was  felt 


OF  EESPIfiATION.  257 

before,  involuntarily  lead  us  to  repeat  this  act  whenever  we  see 
any  one  yawning. 

Sneezing  consists  in  a violent  and  forcible  expiration,  during 
which  the  air,  expelled  with  considerable  rapidity,  strikes  against 
the  tortuous  nasal  passages,  and  occasions  a remarkable  noise. 
The  irritation  of  the  pituary  membrane  determines,  by  sym- 
pathy, this  truly  convulsive  effort  of  the  pectoral  muscles,  and 
particularly  of  the  diaphragm. 

Coughing  bears  a considerable  resemblance  to  sneezing,  and 
differs  from  it  only  in  the  shorter  period  of  duration,  and  the 
greater  frequency  of  the  expirations;  and  as  in  sneezing  the  air 
sweeps  along  the  surface  of  the  pituary  membrane,  and  clears 
it  of  the  mucus  which  may  be  lying  upon  it,  so  the  air,  when  we 
cough,  carries  along  with  it  the  mucus  contained  in  the  bron- 
chiae,  in  the  trachea,  and  which  we  spit  up.  The  violent  cough 
at  the  beginning  of  a pulmonary  catarrh,  the  sneezing  which 
attends  coryza,  show  that  the  functions  of  the  animal  economy 
are  not  directed  by  an  intelligent  principle;  for  such  anarchaeus 
could  not  mistake,  in  such  a manner,  the  means  of  putting  a 
stop  to  the  disease,  and  would  not  call  forth  actions  which,  in- 
stead of  removing  the  irritation  and  inflammation  already  exist- 
ing, can  only  aggravate  them. 

Laughing  is  but  a succession  of  very  short  and  very  frequent 
expirations.  In  hiccup  the  air  is  forcibly  inspired,  enters  the 
larynx  with  difficulty,  on  account  of  the  spasmodic  constriction 
of  the  glottis;  it  is  then  expelled  rapidly,  and  striking  against 
the  sides  of  that  aperture,  occasions  the  particular  noise  attend- 
ing it. 

I shall,  on  another  occasion,  explain  the  mechanism  of  suck- 
ing, of  panting,  and  of  the  efforts  by  which  the  muscles  of  the 
thorax  fix  the  parietes  of  that  cavity,  so  that  it  may  serve  as  a 
fixed  point  for  the  other  muscles  of  the  crunk  and  of  the  limbs. 

Respiration  is  besides  employed  in  the  formation  of  the  voice} 
but  the  voice  and  the  different  modifications  of  which  it  is  capa- 
ble, will  form  the  subject  of  a separate  chapter. 

LXXXVII.  Of  cutaneous  perspiration.  An  abundant  vapour 
is  continually  exhaling  from  the  whole  surface  of  the  body,  and 
is  called  the  insensible  perspiration,  when  in  a state  of  gas  in  the 
air  which  holds  it  in  solution,  it  then  eludes  our  sight;  it  is  cal- 
‘ 2 K 


OF  RESPraATIOK. 


258 

led  sweat  when  in  a greater  quantity  and  in  a liquid  form. 
Sweat  differs,  therefore,  from  insensible  perspiration  only  by 
the  condition  in  which  it  appears;  and  it  is  sufficient  for  its  pro- 
duction, that  the  air  should  be  incapable  of  reducing  it  into 
vapour,  whether  from  an  increased  secretion  by  the  skin,  or 
from  the  dampness  and  consequent  diminished  solvent  powers 
of  the  atmosphere.  The  insensible  perspiration  is  constantly 
escaping  through  the  innumerable  pores  in  the  parietes  of  the 
minute  arteries  of  the  integuments;  it  oozes  in  the  interstices  of 
the  scales  of  the  skin;  the  air  which  immediately  surrounds  our 
body  becomes  saturated  with  it,  and  carries  it  off  as  soon  as  it 
is  renewed.  There  is  the  greatest  resemblance  between  the  cu- 
taneous perspiration  and  the  pulmonary  exhalation;  both  are 
mere  arterial  exhalations,  and  the  mucous  membrane,  which 
lines  the  canals  along  which  the  air  is  transmitted,  is  a mere  pro- 
longation of  the  skin  into  those  organs,  and  into  the  digestive 
tube.  The  surface  from  which  the  cutaneous  perspiration  is 
exhaled,  is  not  quite  so  considerable  as  that  from  which  the 
pulmonary  exhalation  arises,  since  it  is  reckoned  at  only  fifteen 
square  feet  in  a man  of  middle  size.  These  two  secretions  are 
supplementary  to  each  other;  the  increase  of  the  one  is  general- 
ly attended  with  a sensible  diminution  of  the  other;  lastly,  the 
mucous  membrane  of  the  intestinal  canal,  besides  secreting 
mucus,  exhales  likewise  a fluid  which  increases  much  in  quan- 
tity, when  the  cutaneous  perspiration  is  languid,  as  is  proved  by 
the  serous  diarrheas,  so  frequently  occasioned  by  a suppressed 
perspiration.  It  must  be  owned,  however,  that  notwithstanding 
those  analogies  of  structure  and  function  in  the  skin  and  mucous 
membranes,  there  exists  perhaps  a still  more  intimate  connexion 
between  its  action  and  that  of  the  organs  which  secrete  the  urine; 
it  has  always  been  observed,  that  when  this  last  fluid  is  scanty, 
there  is  a greater  cutaneous  perspiration,  and  vice  versa. 

If  we  examine  with  a microscope  the  naked  body,  exposed 
during  summer  to  the  rays  of  a burning  sun,  it  appears  sur- 
rounded with  a cloud  of  steam,  which  becomes  invisible  at  a 
little  distance  from  the  surface.  And  if  the  body  is  placed  before 
a white  wall,  it  is  easy  to  distinguish  the  shadow  of  that  emana- 
tion. We  may,  likewise,  satisfy  ourselves  of  the  existence  of 
the  cutaneous  perspiration  by  the  following  experiment;  hold 


©F  RESPIUATieN. 


259 


the  tip  of  the  finger,  at  the  distance  of  the  twelfth  part  of  an 
inch  from  a looking  glass,  or  any  other  highly  polished  surface; 
its  surface  will  soon  be  dimmed  by  a vapour  condensed  in 
very  small  drops,  which  disappear  on  removing  the  finger.  One 
maj%  in  this  manner,  ascertain  that  the  cutaneous  perspiration 
varies  in  quantity  in  different  parts  of  the  surface  of  the  body; 
for,  on  placing  the  back  of  the  hand  before  a looking  glass,  the 
latter  will  be  covered  by  no  vapour. 

No  function  of  the  animal  economy  has  been  the  subject  of 
more  investigation,  nor  has  any  excited  the  attention  of  more 
accurate  and  indefatigable  physicians,  than  the  secretion  now 
under  consideration.  From  the  time  of  Sanctorius,  who,  in  the 
beginning  of  the  seventeenth  century,  published  in  his  immortal 
work,  “ Medkina  statica'^  the  result  of  experiments  carried  on 
for  thirty  years,  with  a patience  which  very  few  will  imitate,  to 
that  of  Lavoisier,  who  jointly  with  Seguin,  aided  by  the  re- 
sources of  the  improved  stale  of  chemistry,  instituted  an  exami- 
nation of  the  insensible  perspiration,  we  find  engaged  in  this 
inquiry,  Dodart,  who  in  1668  communicated  to  the  Academy  of 
Sciences,  which  had  been  founded  but  a short  time,  the  result 
of  his  observations  at  Paris,  under  a climate  different  from  that 
of  Venice,  where  Sanctorius  lived;  Keill,  Robinson,  and  Rye, 
who  repeated  the  same  experiments  in  England  and  Ireland; 
Linnings  who  performed  his  in  South  Carolina;  and  several 
physiologists  of  no  less  merit,  as  Gorter,  Hartmann,  Arbuthnot, 
Takenius,  Winslow,  Haller,  &c.;  who  all  aimed  at  ascertaining, 
with  more  precision  than  had  been  done  by  Sanctorius,  the  va- 
riations in  the  cutaneous  perspiration;  according  to  the  climate, 
the  season  of  the  year,  the  age,  the  sex,  the  state  of  health 
or  disease,  the  hour  of  the  day,  and  the  quantity  of  the  other 
secretions. 

According  to  Sanctorius,  of  eight  pounds  of  solid  and  liquid 
aliments  taken  in  twenty-four  hours,  five  were  carried  off  by  the 
perspiration,  and  only  three  in  excrement  and  urine.  Haller  con- 
ceives this  cakulation  to  be  exaggerated;  Dodart,  however,  car- 
ried it  still  further,  and  maintained  that  the  relation  of  the  per- 
spiration to  the  solid  excrements,  was  as  seven  to  one. 

In  France  and  in  temperate  climates,  the  quantity  of  the  cu- 
taneous perspiration  and  of  the  urine  is  nearly  the  same;  it  may 


260 


or  RESPIRATION. 


bi*  estimated  at  between  two  and  four  pounds  in  the  twenty-four 
hours.  We  perspire  most  in  summer,  and  void  most  urine  in 
winter.  The  perspiration,  like  every  other  secretion,  is  in  smal- 
ler quantity  during  sleep  than  while  we  are  awake;  in  old  age 
than  during  infancy;  in  weak  persons,  and  in  damp  weather, 
than  under  the  opposite  circumstances. 

The  perspiration  may  be  said  to  be  in  a compound  ratio  of 
the  force  with  which  the  heart  propels  the  blood  into  the  mi* 
nute  capillary  arteries,  of  the  vital  energy  of  the  cutaneous  or- 
gan, and  of  the  solvent  powers  of  the  atmosphere.  The  strongest 
and  most  robust  men  perspire  most;  some  parts  of  the  skin  per- 
spire more  than  others,  as  the  palms  of  the  hands,  the  soles  of 
the  feet,  the  arm  pits,  &c.  When  the  air  is  warm,  dry,  and  fre- 
quently renewed,  cutaneous  perspiration  is  greater,  and  the 
necessity  of  taking  liquid  aliment  is  more  urgent,  and  more 
frequently  experienced;  in  sununer,  as  every  body  knows,  a 
profuse  perspiration  is  brought  on  by  passing  from  the  heat  of 
the  sun  into  the  shade;  and,  on  no  occasion  is  a copious  sweat 
more  easily  brought  on,  than  by  taking  exercise  tn  summer, 
when,  on  the  approach  of  a storm,  the  atmosphere  containing  a 
considerable  quantity  of  vapours,  and  warm  from  the  rays  of  the 
sun,  which  shows  itself  now  and  then  surrounded  by  the  clouds, 
is  little  capable  of  dissolving  the  insensible  perspiration. 

The  skin  may  be  covered  with  sweat  without  any  increase  of 
the  cutaneous  perspiration;  this  may  happen  from  dampness  in 
the  air,  or  from  its  being  imperfectly  renewed.  It  must  be 
owned,  however,  that  sweating  is  more  frequently  occasioned  by 
an  increase  of  the  insensible  perspiration,  and  that  the  warmth 
of  the  bed  which  excites  it,  acts  by  increasing  the  power  of  the 
organs  of  circulation,  and  the  energy  of  the  cutaneous  system. 
The  body  is  weakened  by  sweating,  which  is  seldom  the  case 
with  the  insensible  perspiration.  A profuse  sweat  is  attended 
with  a very  speedy  exhaustion;  thus,  in  hectic  fever,  in  the 
suette  (sudor  ang'licus')  and  other  affections  equally  dangerous, 
it  is  the  cause  of  a wasting  almost  universally  fatal. 

The  matter  of  the  insensible  perspiration  and  of  the  sweat,  is 
in  great  measure  aqueous.  Like  the  urine,  it  holds  in  solution 
several  salts;  also  the  volatilized  recrementitious  matter  of  ani- 
mal spbstances,  sometimes  even  acids,  as  in  the  case  to  which 


0F  RESPIRATION. 


261 

Berthollet  detected  the  phosphoric  acid  in  children  affected 
with  worms,  in  pregnant  women,  in  nurses,  from  whom  there 
exhales  an  odour  manifestly  acid.  It  may  contain  ammonia,  and 
on  certain  occasions,  the  smell  enables  us  to  discover  that  alkali 
in  the  sweat  or  perspiration. 

The  air  which  constantly  surrounds  our  body  does  not  merely 
dissolve  the  aqueous  vapour  which  arises  from  it,  but  several 
physiologists  very  reasonably  conjecture,  that  the  oxygen  of  the 
atmosphere  may  combine  with  the  carbon  of  the  blood  brought 
to  the  skin  by  the  numerous  vessels  which  are  sent  to  it,  and 
likewise  with  the  gelatine,  forming  the  substance  of  the  rete 
raucosum  of  Malpighi. 

The  experiments  of  Jurine,  of  Tingry,  and  of  several  other 
naturalists,  show  that  carbonic  acid  is  constantly  formed  on  the 
surface  of  the  skin,  so  that  the  skin  may  be  considered  as  a 
supplementary  organ  to  that  of  respiration;  and  in  that  point  of 
view,  one  mav  compare  to  it  the  mucous  membranes  which  are 
in  contact  with  the  atmospherical  air  in  the  nasal  fossae,  and  in 
the  intestinal  canal  which  they  line. 

The  cutaneous  perspiration  is,  likewise,  as  was  before  men- 
tioned, a powerful  means  of  cooling  the  body,  and  of  keeping  it 
while  living,  in  a uniform  temperature.  The  water  which  is  ex- 
haled from  the  whole  surface  of  the  body,  carries  off  from  it,  in 
passing  into  vapour,  a considerable  quantity  of  caloric;  and  it  is 
observed,  that  every  thing  which  increases  the  production  of 
caloric,  gives  rise  to  a proportionate  increase  of  the  cutaneous 
perspiration,  and  of  the  pulmonary  exhalation;  so  that  a constant 
equilibrium  being  kept  up  between  its  production  and  escape, 
the  animal  warmth  always  remains  nearly  the  same. 

To  conclude,  the  extremities  of  the  nerves  of  our  organs  of 
sensation  are  all  moistened  by  a fluid  varying  in  quantity-,  and 
which  maintains  them  in  a softened  state,  favourable  to  the  exer- 
cise of  their  functions.  It  was  likewise  necessary  that  the  mem- 
brane in  which  the  sense  of  touch  resides,  should  be  habitually 
kept  moist  by  a fluid  that  should  penetrate  it  throughout;  this 
use  of  the  insensible  perspiration  is  not  less  important  than  the 
preceding,  on  which  physiologists  have  bestowed  most  attention. 


262 


CHAPTER  V. 

OP  THE  SECRETIONS. 

Lxxxviii.  Of  the  animal  Jluids.  The  animal  fluids  were 
formerly  divided  into  recrementitions,  excrementitious,  and  ex- 
cremento-recrementit'iQUs;  this  division,  founded  on  the  uses  to 
which  the  fluids  are  subservient,  is  preferable  to  any  that  has 
since  been  adopted,  and  in  which  they  are  ranked  according  to 
their  nature. 

The  first  class  remain  in  the  body  and  are  employed  in  its 
nutrition  and  growth;  such  as  the  chyle,  the  blood,  the  serosity 
which  lubricates  the  surface  of  the  pleura,  of  the  peritoneum, 
and  of  the  other  membranes  of  the  same  kind.  The  second  kind 
are  ejected  from  our  body,  and  cannot  remain  long  within  it 
without  danger;  such  as  the  urine,  the  matter  of  insensible  per- 
spiration and  of  sweat.  Lastly,  those  of  the  third  class  par- 
take of  the  nature  of  the  two  preceding,  and  are  in  part  rejected, 
while  another  part  is  retained  and  employed  in  the  support  and 
growth  of  the  organ;  this  is  the  case  with  the  saliva,  the  bile, 
the  mucus  of  the  intestines,  &c.  If  one  affected  to  be  very  mi- 
nutely scrupulous,  one  might  consider  all  the  animal  fluids  as 
recremento-excrementitious.  The  chyle  and  the  blood,  which 
are  so  very  nutritious,  contain  an  abundance  of  heterogeneous 
and  excrementitious  parts;  the  urine,  which  of  all  our  fluids 
is  that  which  may,  with  most  propriety,  be  termed  such,  con- 
tains likewise  aqueous  parts,  which,  while  it  remains  in  the 
bladder,  the  lymphatics  absorb,  and  carry  into  the  mass  of  the 
fluids. 

Of  all  the  modern  divisions,  Fourcroy’s  is  the  best;  Vicq-d’- 
Azir  acknowledged  its  superiority  over  that  proposed  by  Haller, 
in  his  physiology.  Fourcroy  admits  six  classes  of  fluids:  1st, 
those  which  hold  salts  in  solution,  as  the  sweat  and  urine;  he 
gives  the  name  of  saline  to  such  fluids:  2d,  inflammable  oily. 
fluids,  all  possessing  a certain  degree  of  consistence  and  con- 
crescibility,  as  fat,  and  the  cerumen  of  the  ears,  &c.:  3d,  the  sapo- 
naceous fluids,  as  the  bile  and  the  milk:  4th,  the  mucous  fluids, 


OF  THE  SECRETIONS.  553 

as  those  which  lubricate  the  internal  coat  of  the  Intestinal  canal: 
5th,  the  albuminous  fluids,  among  which  one  may  rank  the  se- 
rum of  the  blood.  The  fibrinous  fluids,  containing  iibrina,  as 
the  fluid  last  mentioned. 

In  proportion  as  we  advance  in  our  knowledge  of  animal 
chemistry,  the  defects  of  these  divisions  become  more  and  more 
evident.  In  short,  the  animal  fluids  are  so  compound,  that  there 
is  not  one  which  does  not,  at  once,  belong  to  several  of  these 
classes,  and  whose  prevailing  element  is  not  sometimes  exceed- 
ed in  quantity,  by  materials  which  commonly  form  but  a small 
part  of  them. 

LXXXIX.  The  blood  is  the  reservoir  and  the  common  source 
of  the  fluids;  these  do  not  exist  in  the  blood,  with  the  qualities 
which  characterize  them,  unless,  after  having  been  previously 
formed  by  the  secretory  organs,  they  have  been  absorbed  by 
the  lymphatics,  and  conveyed,  with  the  chyle  and  lymph,  into 
the  circulatory  system.  Let  us  shortly  attend  to  its  nature,  al- 
though this  belongs  more  especially  to  the  department  of  che- 
mistry. The  blood  is  red  in  man  and  in  all  warm-blooded  ani- 
mals, and  even  in  some  whose  temperature  is  not  very  different 
from  that  of  the  atmosphere,  as  in  fishes  and  reptiles.  This 
colour,  of  a deeper  or  lighter  shade,  according  as  the  blood 
is  drawn  from  an  artery  or  a vein,  varies  in  its  degree  of  in- 
tensity, according  to  the  state  of  health  or  weakness.  It  is  of  a 
deep  red  in  strong  and  active  persons,  pale  and  colourless  in 
dropsical  patients,  and  whenever  the  health  is  weak.  By  its 
colour,  one  may  judge  of  all  its  other  qualities.  Its  viscidity  is 
greater,  its  saline  taste  more  marked,  its  peculiar  smell  stronger, 
when  its  colour  is  deep.  This  colour  is  produced  by  a prodi- 
gious number  of  globular  molecules,  which  move  and  float  in 
an  aqueous  and  very  liquid  fluid.  When  the  blood  is  pale,  the 
number  of  these  molecules  diminishes,  they  seem  to  be  dis- 
solved in  cachexise. 

The  microscope,  which  affords  the  only  method  of  perceiving 
them,  does  not  enable  one  to  determine  their  bulk  and  their 
figure.  Leeuwenhoek,  who  brought  forward  the  idea  of  their 
being  so  minute,  by  his  calculation,  that  they  were  one  millionth 
part  of  an  inch  in  size,  thought  them  spherical.  Hewson  says 


264 


OF  THE  SECRETIONS. 


they  are  annular  and  have  an  opening  in  their  centre.  Others 
compare  them  to  a flattened  lentil,  with  a dark  spot  in  the  mid- 
dle. They  are  solid,  and  formed  by  a nucleus  or  red  point  co- 
vered over  by  a membranous  vesicle,  which  appears  to  be  readily 
formed  and  destroyed. 

XC.  The  blood,  when  no  longer  in  the  course  of  the  circula- 
tion, and  on  being  received  into  a vessel,  parts  with  its  caloric 
and  exhales,  at  the  same  time,  a powerful  smell,  a gas  to  which, 
according  to  some  physiologists  (Moscati,  Rosa,  &c.),  it  owes 
its  vital  properties,  and  the  absence  of  which  is  attended  with  a 
loss  of  its  vitality;  so  that  its  analysis  cannot  furnish  facts  appli- 
cable to  the  explanation  of  the  phenomena  of  health  and  dis- 
ease. This  odour,  extremely  strong  in  carnivorous  animals,  is 
very  distinguishable  in  man,  especially  in  arterial  blood.  I re- 
member retaining  it,  a whole  day,  in  my  throat,  after  removing 
the  dressings,  and  suppressing  a hemorrhage,  occasioned  by  a 
relaxation  of  the  ligatures,  a week  after  the  operation  for  popli- 
teal aneurism.  Unless  by  agitation  it  is  prevented  from  coagu- 
lating, as  it  cools,  its  consistence  increases,  and,  on  being  laid 
by,  it  separates  into  two  very  different  parts,  the  one  aqueous, 
more  or  less  red,  heavier  than  common  water,  and  evidently 
saltish;  this  is  called  the  serum,  consisting  of  water,  in  which 
are  dissolved  albumen,  gelatine,  soda,  phosphates,  and  muriates 
of  soda,  nitrate  of  potash,  and  muriate  of  lime. 

Serum,  though  bearing  some  analogy  to  the  albumen  of  egg, 
differs  from  it,  in  forming,  on  coagulating,  a less  solid  and  less 
homogeneous  mass.  The  albumen  is  evidently  mixed  with  a 
portion  of  transparent  gelatine,  not  coagulable  by  heat.  Albu- 
men has  so  great  an  attraction  for  oxygen,  that  it  is  fair  to  pre- 
sume, that  the  serum  absorbs  oxygen  and  combines  with  it, 
through  the  very  thin  parietes  of  the  air  cells  of  the  lungs,  and 
that  it  gives  to  arterial  blood  that  spumous  appearance  which  is 
one  of  its  distinguishing  characters.  This  oxydizement,  and  the 
fixation  of  the  caloric  which  accompanies  it,  equally  increase 
its  consistence.  It  does  not,  however,  coagulate;  because  it  is 
kept  in  perpetual  motion  by  the  circulatory  action,  and  is  dilu- 
ted by  a sufiicient  quantity  of  water;  because  the  animal  tem- 


OF  THE  SECRETIONS. 


265 

perature,  which  never  exceeds  thirty-two  or  thirty-four  degrees, 
cannot  give  a solid  form  to  albumen,  which  coagulates  only  at 
fifty  degrees  of  Reaumur’s  thermometer;  and  lastly,  because  as 
serum  contains  a certain  quantity  of  uncombined  soda,  which 
enables  it  to  turn  green,  vegetable  blues;  this  alkali  concurs  in 
keeping  the  albumen  in  a dissolved  state,  which  it  renders  fluid, 
when  it  has  been  coagulated  by  the  acids,  by  heat,  or  by  alcohol. 

Amid  the  serum,  and  on  its  surface,  there  floats  a red  cake, 
spungy,  and  solid  {insula  rubra)  which,  by  repeated  washing, 
may  be  separated  into  two  very  distinct  parts.  The  one  is  the 
cruor  or  the  colouring  matter  which  mixes  with  the  water;  it  is 
a more  highly  oxygenated  and  more  concrescible  albumen  than 
that  of  the  serum;  it  holds  in  solution  soda,  as  well  as  phosphate 
of  iron,  with  an  excess  of  iron. 

The  other  is  a solid  and  fibrous  substance,  which,  after  being 
repeatedly  washed  has  the  appearance  of  felt,  the  filaments  of 
which  cross  each  other,  are  extensible  and  very  elastic.  This 
third  part  of  the  blood  is  called  Jibrina^  it  is  very  similar  in  its 
nature  to  muscular  fibre,  and  like  it,  gives  out,  on  distillation,  a 
considerable  quantity  of  carbonate  of  ammonia.  Fibrina  does 
not  exist  in  the  blood  in  a solid  form,  but  in  a state  of  solution 
and  combined  with  the  other  constituent  parts  of  the  fluid,  as 
is  indicated  by  the  appropriate  expression  of  liquid  flesh  (chair 
coulante')  first  used  by  Bordeu,  in  speaking  of  the  blood. 

XCI.  If  the  blood  be  exposed  to  the  action  of  fire,  if  it  be 
calcined  and  reduced  to  powder,  and  if  this  pulverized  sub- 
stance be  exposed  to  a magnet,  the  presence  of  iron  will  be 
manifestly  seen  by  the  magnetic  attraction.  Authors  do  not 
agree  in  their  accounts  of  the  quantity  of  iron  contained  in  the 
blood.  Menghini  says,  there  is  one  part  in  the  hundred;  others 
that  it  is  in  the  proportion  of  1 to  303;  so  that  it  is  probable, 
that  this  constituent  principle  of  the  blood,  like  all  the  materials 
of  our  fluids,  may  vary  in  quantity,  according  to  different  cir- 
cumstances. 

Blumenbach  justly  observes,  that  iron  is  found  only  in  cal- 
cined blood;  that  none  is  to  be  found  if  it  be  slowly  dried.  This 
peculiarity  is  no  longer  surprising,  since  M.  Fourcroy  has 
shown  that  iron  existed  in  the  blood,  in  combination  with  the 

2 L 


266 


OF  THE  SECRETIONS, 


phosphoric  acid,  and  formed  with  that  acid  a phosphate  of  iron, 
with  an  excess  of  its  base.  This  salt  becomes  decomposed  by 
calcination,  the  iron  is  set  free  and  is  acted  upon  by  the  magnet. 
Physiologists  attribute  the  colour  of  the  blood,  to  the  presence 
of  the  oxide  of  iron  in  that  fluid. 

It  is,  at  present,  the  received  opinion,  that  the  red  colour  of 
the  blood  is  owing  to  the  presence  of  phosphate  of  iron,  which 
being  conveyed,  of  a white  colour,  into  the  blood,  along  with 
the  chyle,  meets  with  the  pure  soda,  by  which  it  is  dissolved, 
and  from  which  it  receives  its  colour;  the  colour  of  the  blood 
is,  likewise,  owing  to  the  oxidizement  of  the  metallic  portion, 
which  is  in  very  considerable  quantity  in  that  salt.  This  solu- 
tion of  the  phosphate  of  iron  by  soda,  the  oxidizement  of  the 
excess  of  iron,  and  the  absorption  of  oxygen  by  albumen,  con- 
stitute, in  an  especial  manner,  hematosis  or  sanguification^  which 
is  principally  carried  on  in  the  lungs. 

The  respective  proportion  of  the  three  parts  into  which  the 
blood  separates  spontaneously,  varies  considerably.  The  serum 
constitutes  about  one  half  or  three  fourthsof  thefluid;  the  colour- 
ing matter  andfibrina  are  in  inverse  ratio  of  the  serum,  and  it  is 
observed,  that  the  more  brilliant  and  red  the  colour  of  the  blood, 
the  greater  the  proportion  of  the  fibrous  part.  The  pale,  aqueous, 
and  colourless  blood  of  a dropsical  patient  contains  very  little 
fibrina.  In  putrid  or  adynamic  fever,  in  which  bleeding,  as  is  uni- 
versally known,  is  improper,  I have  sometimes  seen  the  blood 
containing  but  a small  portion  of  fibrina,  and  very  slow  of  coagu- 
lating; its  texture  seemed  to  sulfer  from  the  affection  under  which 
the  muscular  organs  were  evidently  labouring.  In  inflammatoty 
diseases,  on  the  contrary,  the  plastic  power  of  the  blood  is  aug- 
mented; the  fibrina  is  in  greater  quantity,  even  the  albumen 
coagulates  spontaneously  and  forms  a crust  above  the  serum, 
which  is  always  in  smaller  quantity. 

XCII.  Of  the  changes  of  the  blood.  The  fluids  not  only  un- 
dergo changes  in  their  composition,  in  their  qualities,  and  na- 
ture, when  the  action  of  the  solids  is  itself  altered,  but  even  the 
absorbent  system  may  introduce,  into  the  mass  of  our  fluids, 
heterogeneous  principles,  evidently  the  cause  of  several  dis- 
eases. In  this  manner  all  contagions  spread,  the  virus  of  small 
pox,  of  syphilis,  of  the  plague,  &c.  Thus,  in  time,  the  habitual 


OF  THE  SECRETIONS. 


267 

use  of  the  same  aliment  produces  in  our  fluids  a crasis  or  pecu- 
liar constitution  which  has,  on  organized  solids,  an  influence 
acting  even  on  the  mind.^ 

• These  opinions  of  our  author  are  evidently  borrowed  from  the  humoral 
pathology.  Of  this  absurd  system,  much  is  still  retained,  and  especially  by  the 
French  pathologists.  We  believe  that  the  changes  wrought  in  the  fluids  are 
wholly  produced  through  the  intervention  of  the  solids  Not  the  slightest 
proof  exists  of  their  being  vitiated  by  the  introduction  of  “ heterogeneous 
principles”  much  less  that  this  mixture  is  the  “ cause  of  several  diseases.”  It  is 
manifest  that  every  portion  of  the  absorbent  system,  has  the  power,  in  a very 
great  degree,  of  digesting  and  animalizing  the  substances  which  are  taken  up. 
This  pro])erty  of  the  absorbents  is  a provision  of  nature  to  prevent  noxious 
substances  from  penetrating  into  the  circulation  unchanged.  In  most  instances 
they  are  fully  adequate  to  this  end.  Where  they  are  not,  the  substance  passes 
to  the  first  lymphatic  gland,  which  takes  on  inflammation  and  intercepts  its 
further  progress,  as  in  the  case  of  bubo.  In  this  respect  therefore,  the  conglo- 
bate glands  may  be  considered  as  centinels  guarding  the  exterior  approaches 
of  the  body. 

We  are  not  ignorant  that  some  of  the  properties  of  certain  substances  when 
absorbed  display  themselves  in  the  secretions  and  excretions,  as  the  odour 
of  garlick,  the  colouring  matter  of  madder,  &c.  &c.  But  it  does  not  hence 
follow  that  they  entered  the  circulation  unchanged. 

Experiments  indeed,  prove  quite  the  contrary,  as  neither  one,  nor  the  other, 
can  be  detected  in  the  serum  of  the  blood.  It  seems  to  us  most  probable,  that 
the  process  of  assimilation,  whether  performed  by  the  chylopoietic  viscera, 
or  by  the  absorbent  apparatus,  completely  decomposes  all  substances  subject- 
ed to  its  influence,  and  however  various  in  their  principles,  reduces  them  to 
one  homogeneous  fluid,  bland  and  inoperative  in  its  nature,  or  in  other  words 
renders  it  fit  for  the  purpose  of  nutrition.  But,  in  the  excretions  or  secretions, 
being  removed  beyond  the  sphere  of  the  vital  powers,  chemical  action  takes 
place,  by  which  those  substances  are  in  part  or  entirely  regenerated. 

Whether  the  particular  explanation  offered  by  this  hypothesis  be  received 
or  not,  the  fact  at  least  must  be  acknowledged,  that  no  substance  in  its  active 
condition  does  enter  the  circulation,  since  experiments  have  shown  that  how- 
ever mild  the  fluid  may  be,  either  milk  or  mucilage,  oil  or  pus,  it  cannot  even 
in  the  smallest  quantity  be  injected  directly  into  the  blood-vessels  without 
occasioning  the  most  fatal  consequences.  As  regards  the  operation  of  sub- 
stances on  the  living  system,  we  do  not  think  it  at  all  necessary  to  resort  to 
the  circulation  as  a medium  through  which  it  is  effected.  By  referring  it  to 
that  law  of  the  animal  economy  termed  sympathy  or  consent  of  parts,  we 
have  a rationale  far  more  consistent  with  those  views  derived  from  the  present 
improved  state  of  our  knowledge. 

Conformably  to  this  theory,  when  a substance  either  medicinal  or  poisonous  is 
applied  to  a susceptible  portion  of  the  body,  externally  or  internally,  an  action  is 
excited  which  is  extended,  more  or  less  according  to  the  diff'usibility  ofthe  pro- 
perties of  the  substance,  or  the  degree  of  sympathetic  connection  which  the  part 


268 


OF  THE  SECRETIOXS. 


A purely  vegetable  diet  conveys  into  the  blood,  according  to 
Pythagoras,  bland  and  mild  principles.  This  fluid  excites  the 
organs  in  a moderate  degree,  and  this  check  over  the  physical 
excitement,  faci'litates  the  observance  of  the  laws  of  temperance, 
the  original  source  of  all  virtues.  These  observations  of  ancient 
phll  osophy,  on  the  influence  of  regimen,  have,  doubtless,  led 
their  authors  to  exaggerated  inferences,  but  they  should  not  be 
considered  as  altogether  unsupported.  The  carnivorous  species 
are  marked  by  their  strength,  their  courage,  and  their  ferocity; 
savages  who  live  by  hunting,  and  who  feed  on  raw,  bloody,  and 
palpitating  flesh,  are  the  most  ferocious  of  men;  and,  in  our  own 
country,  in  the  midst  of  those  scenes  of  horror  which  we  have 
witnessed,  and  from  which  we  have  suflTered,  it  was  observed, 
that  butchers  were  foremost  in  the  massacres,  and  in  all  the  acts 
of  atrocity  and  barbarity.  I know  that  this  fact,  which  was  uni- 
formly noticed,  has  been  explained  by  saying,  that  the  habit  of 
slaving  animals,  had  familiarized  them  to  shed  human  blood. 
But  though  I do  not  deny  the  existence  of  this  moral  cause, 
which  certainly  operates,  I think  I may  add  to  it  as  a physical 
cause,  the  daily  and  plentiful  use  of  animal  food,  the  breathing 
an  air  filled  with  emanations  of  the  same  kind,  which  they  in- 
may have  with  the  body  generally.  Thus  a set  of  actions  is  raised,  everyone  of 
which  is  precisely  similar,  provided  they  are  confined  to  the  same  system,  by 
which  is  to  be  understood,  parts  of  an  Identity  of  structure  If,  however,  the 
chain  runs  into  other  s)’^stems,  it  loses  its  homogeneous  character,  the  actions 
being  modified  according  to  the  peculiar  organization  of  the  parts  in  which 
they  may  take  place. 

To  illustrate,  the  more  distinct!}',  our  meaning,  we  will  state  a very  fami- 
liar case  By  inserting  a particle  of  variolous  matter  under  the  skin,  local  irrita- 
tion is  created:  m a few  days  this  action  becomes  diffused,  and  a fever  ensues, 
which  after  a short  continuance  throws  out  an  eruption,  each  pustule  of  which 
is  alike,  because  the  surface  of  the  body  is  of  a uniform  structure,  containing 
exactly  the  same  sort  of  virus  as  the  primarv’  or  parent  pustule.  It  is  in  this 
way.  that  morbid  motion  distributes  itself.  When  diseases  arise  from  a point, 
as  in  fact  all  diseases  do,  but  more  strikingly  those  occasioned  by  inoculation, 
the  matter  introduced  is  not  infinitely  divided  and  spread  over  the  body,  but 
the  action  which  that  matter  had  originally  excited.  These  are  general  prin- 
ciples, which  apply  to  the  sysiem  in  every  condition,  and  explain  the  modus 
operand!  of  medicines  as  well  as  of  the  causes  of  disease.  Whatever,  in  short, 
operates  on  the  living  frame  is  obedient  to  the  same  laws.  The  spot  first  acted 
upon,  is  the  focus  from  which  is  irradiated  the  more  diffused  impressions.  Ed. 


OF  THE  SECRETIONS. 


269 

hale,  and  which  contribute  to  their  embonpoint^  which  is  some- 
times excessive. 

As  the  plasticity  and  concrescibility  of  the  blood  are  diminish- 
ed in  asthenic  diseases  or  of  debility,  as  putrid  fevers  and  scurvy, 
two  causes  may  be  assigtied  for  the  hemorrhages  which  come  on 
in  those  diseases,  viz.  the  relaxed  state  of  the  vessels  and  the 
dissolution  of  the  blood.  In  scurvy,  the  tissue  of  the  capillaries 
is  relaxed,  its  meshes  enlarged,  red  blood  passes  into  them,  tran- 
sudes through  their  parietes,  and  forms  scorbutic  spots.  I have 
sometimes  seen  those  ecchymoses  or  sanguineous  cutaneous 
transudations  extend  under  the  skin  of  the  whole  of  one  lower 
extremity.  Petechise,  in  putrid  fever,  are  formed  in  the  same 
manner,  and  depend,  likewise,  on  the  relaxation  of  the  minute 
vessels,  and  on  the  greater  fluidity  of  the  blood,  whose  mole- 
cules are  less  coherent,  and  more  readily  separated  from  each 
other. 

In  the  summer  of  the  year  1801,  I amputated  the  arm  of  an 
old  man  of  sixty,  on  account  of  a corroding  and  varicose  ulcer, 
which  for  thirty  years  had  occupied  a part  of  the  forearm,  and 
extended  to  the  elbow.  All  who  were  present  at  this  operation, 
observed  that  the  blood  which  flowed  from  the  arteries,  was  no4 
nearly  so  red  as  that  from  the  arteries  of  a young  man,  whose 
thigh  had  just  been  taken  off,  on  account  of  a scrophulous  caries 
of  the  leg;  that  the  venous  blood  was  entirely  dissolved,  purple, 
and  similar  to  a weak  dye  of  logwood.  This  blood  did  not  co- 
agulate like  that  of  the  young  man,  it  became  fluid  and  was  con- 
verted into  serum  containing  a few  colourless  clots. 

Those  whohave  endeavouredtofind,  in  the  changes  undergone 
by  the  blood  and  the  other  fluids,  the  cause  of  all  diseases,  have 
fallen  into  as  serious  blunders  as  the  determined  solidists,  who 
maintain  that  all  diseases  arise  from  a deranged  condition  of  the 
solids,  and  that  every  change  in  the  condition  of  the  fluids  is  a 
consequence  of  that  derangement.  The  believers  in  the  humoral 
pathology,  have  certainly  gone  too  far;  they  have  admitted  that 
the  animal  fluids  might  be  acid^  alkalescent^  acrimonious,  while 
we  have  no  proof  whatever  that  they  ever  do  undergo  such 
changes.  The  solidists  have,  likewise,  gone  much  beyond  the 
truth,  in  saying,  that  every  primitive  change  in  the  condition  of 


OP  THE  SECRETIONS. 


270 

the  fluids  is  imaginary,  and  that  the  doctrine  of  humoral  patho- 
logy is  without  foundation.  Stahl  relates*  that  the  blood  of  a 
young  woman,  who  was  bled  during  a fit  of  epilepsy,  was  abso- 
lutely coagLilated,  as  if  that  fluid  had  partaken  in  the  rigidity  af- 
fecting the  muscular  organs.  Some  authors  say  they  have  met 
with  the  same  appearance;  I have,  however,  never  been  able  to 
discover  any  sensible  difference  between  the  blood  of  an  epilep- 
tic patient  and  of  any  other  person  of  the  same  constitution  of 
the  same  age,  and  living  on  the  same  regimen;  and  it  should  be 
considered,  that  to  make  a just  comparison  of  our  fluids,  it  is  ne- 
cessary that  every  thing  should  be  alike  in  the  persons  from 
whom  they  are  taken,  with  the  exception  of  the  difference  of 
which  we  are  to  judge.  In  fact,  the  blood  has  not  the  same  ap- 
pearance, and  does  not  coagulate  in  the  same  manner  when 
taken  from  a child,  a woman,  or  an  old  man;  from  a man  who 
lives  abstemiously,  or  from  one  who  lives  on  a full  diet. 

After  enumerating  the  changes  which  the  blood  undergoes, 
one  might  speak  of  those  which  affect  the  fluids  that  are  formed 
from  it;  one  might  attend  to  the  greenish,  leek  colour,  and  some- 
times even  darkish  appearance  of  the  bile,  which  is  not  always 
of  the  same  degree  of  bitterness;  the  limpid  state  of  the  urine, 
which  is  voided  colourless,  without  smell  or  flavour,  after  a fright, 
or  during  the  convulsive  fits  of  hysterical  women;  the  fetid  smell 
and  the  viscidity  of  the  saliva,  when  the  salivary  glands  are  un- 
der mercurial  influence;  the  milky  state  of  the  serum  which  lu- 
bricates the  parietes  of  the  abdomen  and  of  the  viscera  which  it 
contains,  after  inflammation  of  the  peritoneum;  changes  which, 
almost  universally,  depend  on  a derangement  of  action  in  the  se- 
cretory organs,  and  sometimes,  likewise,on  the  general  condition 
of  the  fluids;  for  a gland  cannot  secrete  a fluid  endowed  with 
the  qualities  which  peculiarly  belong  to  it,  unless  the  blood  fur- 
nish it  with  the  materials  of  secretion,  and  unless  it  be  in  a state 
to  bring  about  a due  combination  of  their  particles.  When  we 
come  to  the  article  of  accidental  secretions,  we  shall  speak  of 
some  of  those  disorders  of  the  fluids,  depending  on  a depraved 
eondition  of  the  secretory  organs. 

XCIIl.  On  the  transfusion  of  blood.  In  the  midst  of  the  dis- 


* Theoria  medica  vera,  page  6r8. 


OF  THE  Secretions. 


271 

putes  to  which  the  discovery  of  the  circulation  gave  rise,  some 
physicians  conceived  the  idea  of  renovating  completely  the  whole 
mass  of  the  fluids,  in  persons  in  whom  they  might  be  vitiated,  by 
filling  their  vessels  with  the  blood  of  an  animal  or  of  a person  in 
good  health.  Richard  Lower,  known  by  his  work  on  the  heart, 
first  practised  it  on  dogs,  in  1665.  Two  years  afterwards,  trans- 
fusion was  performed  at  Paris  on  men,  and  excited  the  greatest 
expectations:  it  was  thought  that  by  this  process,  called  trans- 
fusing surgery  {chirurgie  transfusoire)^  all  remedies  would  be 
superseded,  that  henceforth,  to  cure  the  most  serious  and  inve- 
terate diseases,  it  would  be  necessary  merely  to  transfuse  the 
blood  of  a strong  and  healthy  man  into  the  veins  of  the  diseased; 
nay,  they  went  so  far  as  actually  to  imagine  they  might  realize 
the  fabulous  fountain  of  Jouvence;  they  expected  no  less  than 
to  restore  youthful  vigour  to  the  old,  by  infusing  into  them  the 
blood  of  the  young,  and  thus  to  perpetuate  life.  All  these  bril- 
liant chimeras  soon  vanished;  some  underwent  the  experiment 
without  any  remarkable  effects  from  it,  others  were  affected  with 
the  most  violent  delirium;  a lad  of  fifteen  lost  his  senses,  after 
suffering  two  months  from  the  most  violent  fever.  The  legislative 
authority  at  last  interfered,  and  prohibited  those  dangerous  ex- 
periments. 

The  experiments  on  the  subject  of  the  transfusion  of  blood 
were  repeated, but  without  success,  at  the  Academy  of  Sciences. 
Perrault  opposed  this  new  method,  and  showed  that  it  was  very 
difficult  for  one  animal  to  exist  on  the  blood  of  another;  that  this 
fluid,  though  apparently  the  same  in  animals  of  the  same  age, 
was  as  different  from  it  as  the  features  of  their  face,  their  tem- 
per, &c. ; that  an  extraneous  fluid  was  thus  introduced,  which  con- 
veying to  the  organs  an  irritation  to  which  they  were  not  accus- 
tomed, must  disorder  their  action  in  various  ways;  that  if,  as  an 
objection  to  what  he  had  said,  they  should  bring  forward  what 
takes  place  in  grafting,  in  which  the  sap  of  one  tree  nourishes 
another  of  a different  kind,  he  would  answer,  that  vegetation 
does  not  depend  on  so  complicated,  nor  on  so  delicate  a me- 
chanism as  the  nutrition  of  animals;  that  a hut  may  be  formed  of 
all  kinds  of  stones  taken  at  random,  but  that  to  build  a palace, 
stones  must  be  designedly  shaped  for  the  purpose,  so  that  a stone 


OF  THE  SECRETIONS, 


272 

destined  for  an  arch,  will  not  do  for  a wall,  nor  even  for  another 
arch.'* 

It  would  be  easy,  by  means  of  a curved  tube,  to  transfuse  the 
arterial  blood  of  an  animal,  from  a wound  in  its  carotid  artery, 
into  the  saphena  vein  of  a man,  into  the  internal  jugular,  or  into 
some  of  the  cutaneous  veins  of  the  fore  arm;  but  it  is  to  be  pre- 
sumed, from  experiments  on  living  animals,  that  it  would  be  very 
difficult  to  transfuse  blood  into  the  arteries,  as  these  vessels,  filled 
with  blood,  during  life,  do  not  yield  to  a greater  distention.  The 
capillaries,  in  which  the  arteries  terminate,  become  corrugated 
a'hd  refuse  to  transmit  a fluid  which  does  not  act  upon  them,  ac- 
cording to  their  wonted  sensibility.  Such  was  the  result  of  the 
experiments  of  Professor  Buniva;  he  observed  in  a living  calf, 
that  the  vessels  did  not  transmit  freely  the  fluid  which  was 
forced  into  them,  till  the  instant  when  the  animal  w'as  killed,  b)' 
dividing  the  upper  part  of  the  spinal  marrow.  Attempts  have  been 
made  to  turn  to  useful  purposes  these  experiments  on  transfusion, 
by  limiting  the  process  to  the  injecting  of  medicinal  substances 
into  the  veins.  It  is  singular,  that  the  moment  a fluid  is  injected 
into  the  veins  of  an  animal,  it  endeavours  to  perform  motions  of 
deglutition,  as  if  the  substance  had  been  taken  in  at  the  mouth. 
All  these  attempts  have  been  too  few  in  number,  and  are  not  suf- 
ficiently authenticated  to  justify  their  application  to  the  human 
subject.  But  there  is  every  reason  to  believe,  that,  even  with 
the  utmost  care,  the  life  of  those  who  should  submit  to  them 
would  be  endangered;  so  that  it  is  at  once  humane  and  prudent 
to  abstain  from  them. 

XCIV.  Of  the  secretions.  It  has  been  said,  in  too  general  a 
way,  that  the  organs  receive  from  the  blood  conveyed  to  them 
by  the  arteries,  the  materials  of  the  fluids  which  they  separate 
from  it.  We  have  seen,  that  the  liver  is  a remarkable  exception 
to  this  general  rule;  the  same  observation  seems  likewise  appli- 
cable to  the  mammae;  they  appear  to  receive  the  elements  of 
their  milky  secretion  from  the  lymphatics,  which  are  so  very 
numerous  in  their  structure. 

One  is,  therefore,  justified  in  saying,  that  the  elements  of 
our  fluids  may  be  furnished  by  vessels  of  every  kind,  to  the 


Academic  royale  des  Sciences,  166r,  page  37. 


OF  THE  SECRETIONS. 


273 

•rgans  in  which  such  fluids  may  be  elaborated.  The  term 
secretion^  whatever  its  etymology  may  be,  denotes  that  function 
by  which  an  organ  separates  from  the  blood  the  materials  of  a 
substance  which  does  not  exist  in  that  fluid,  with  its  characte- 
ristic qualities.  By  the  term  secretion, one  should  not,  therefore, 
understand  the  mere  separation  of  a fluid  existing  before  the 
action  of  the  organ  by  which  it  is  prepared. 

XCV.  The  differences  between  the  secreted  fluids  are  evi- 
dently connected  with  those  of  the  organs  employed  in  their 
formation.  Thus,  the  arterial  exhalation  which  takes  place, 
throughout  the  whole  extent  of  the  internal  surfaces,  maintains 
their  contiguity,  throws  out  an  albuminous  serosity  which  is 
merely  the  serum  of  the  blood,  slightly  changed,  by  the  feeble 
action  of  a very  simple  organization.  The  analysis  of  the  fluid 
of  dropsy,  which  is  merely  the  serosity  constantly  transuding 
from  the  surface  of  the  serous  membranes,  as  the  pleura  and 
peritoneum,  shows,  that  it  bears  the  strongest  resemblance  to 
the  serum  of  the  blood,  and  that  it  differs  from  it,  only  in  the 
varying  proportions  of  albumen  and  of  the  different  salts  which 
it  holds  in  solution. 

This  first  kind  of  secretion,  this  perspiratory  transudation, 
would  seem  to  be  a mere  filtration,  through  the  pores  of  the 
arteries,  of  a fluid  already  formed  in  the  blood.  There  is,  how- 
ever, besides,  an  inherent  action  in  the  membranes  whose  sur- 
face it  continually  lubricates.  If  it  were  not  for  this  action,  the 
serum  would  remain  united  to  the  other  constituent  parts  of  the 
fluid,  which  is  in  too  much  motion,  and  at  too  high  a tempera- 
ture, to  allow  of  a spontaneous  separation.  The  term  exhalation, 
which  is  applied  to  this  secretion,  gives  an  incorrect  idea  of  it; 
for  exhalation,  which  is  a purely  physical  phenomenon,  and  re- 
quiring the  presence  of  air  to  dissolve  the  fluid  that  is  exhaling, 
cannot  take  place  from  surfaces  that  are  in  absolute  contact,  and 
between  which  there  is  no  interval.  The  character  of  this  mode 
of  secretion  is  the  absence  of  any  intermediate  substance  be- 
tween the  vasa  afferentia  and  the  excretorv  ducts;  the  minute 
arteries  and  veins  which  enter  into  the  structure  of  the  mem- 
branes being,  at  once,  vasa  aflPerentia  and  excretory  ducts.  The 
fluid  secreted  by  the  serous  membranes,  though  bearing  a con- 
siderable analogy  to  the  serum  of  the  blood,  differs  from  it 

2 M 


OF  THE  SECRETIONS. 


274 

however,  by  being  animalized  in  a greater  degree.  The  most 
important  function  of  these  organs  is,  therefore,  that  they  concur 
in  the  common  process  of  assimilation;  the  office  which  has 
been  long  assigned  to  them  of  facilitating  the  motion  of  the 
organs  which  they  envelop,  by  lubricating  their  surface,  will 
appear  to  be  of  very  secondary  importance,  if  it  be  considered, 
that  respiration  is  not  impeded  by  adhesions  between  the  lungs 
and  the  pleura,  and  that,  besides,  the  brain,  which  when  the 
cranium  is  whole,  is  completely  motionless,  is  entirely  surround- 
ed by  a serous  membrane. 

XCVI.  Next  in  order  to  the  serous  transudation,  which 
requires  a very  simple  organization,  comes  the  secretion  which 
takes  place  in  the  cryptse,  in  the  glandular  follicles  and  in  the 
mucous  lacunae.  Each  of  these  small  glands,  contained  within 
the  membranes  lining  the  digestive  canal,  the  air  tubes,  and  the 
urinary  passages,  and  the  collection  of  which  forms  the  amyg- 
dalae, the  arytenoid  glands,  &c.  may  be  compared  to  a small 
bottle  with  a round  bottom,  and  a very  short  neck;  the  mem- 
branous parietes  of  thse  vesicular  crj'ptse  receive  a considerable 
number  of  vessels  and  nerves.  The  peculiar  action  of  the  parietes 
of  these  different  parts,  determines  the  secretion  of  the  mucus 
furnished  by  those  glands.  These  mucous  fluids,  less  liquid  and 
more  viscid  than  the  serosity  which  is  the  product  of  the  first 
mode  of  secretion,  contain  more  albumen  and  a greater  number 
of  salts,  differ  still  more  from  the  serum  of  the  blood,  and  are  of 
a more  excrementitious  nature. 

The  bottom  of  these  utricular  glandulas  is  turned  towards  the 
parts  to  which  the  mucous  membranes  adhere;  their  mouth,  or 
neck,  opens  on  the  surface  at  which  those  membranes  are  in 
contact.  These  kinds  of  excretory  ducts,  wider,  or  narrower, 
and  always  very  short,  sometimes  unite,  run  into  each  other, 
and  open  within  the  cavities.  These  common  orifices,  at  which 
several  mucous  glands  empty  themselves,  are  easily  seen  on 
the  amygdalae,  towards  the  mucous  lacunae  of  the  rectum  and 
of  the  urethra,  at  the  base  of  the  tongue,  &c.  The  albuminous 
fluid,  which  is  poured  within  those  glandular  cryptae,  remains 
some  time  within  the  cavity,  becomes  thicker  from  the  absorp- 
tion of  its  more  fluid  parts;  for  there  are,  likewise,  lymphatics 
within  the  texture  of  their  parietes.  When  the  surfaces,  on 


OF  THE  SECRETIONS. 


275 

which  they  are  situated,  require  to  be  moistened,  this  small 
pouch  contracts,  and  throws  up  the  fluid  with  which  it  is  filled. 
The  secretion  and  excretion  are  promoted  by  the  irritation 
which  the  presence  of  the  air,  of  the  aliment,  or  of  the  urine 
occasions,  by  the  compression  exerted  by  those  substances,  and 
lastly,  by  the  peristaltic  contractions  of  the  muscular  planes  to 
which  the  mucous  membranes  adhere,  throughout  the  whole 
extent  of  the  digestive  tube. 

XCVII.  Those  fluids  which  differ  much  from  the  blood, 
require,  for  their  secretion,  organs  of  a more  complicated 
nature;  such  organs  are  called  conglomerate  glands,  to  dis- 
tinguish them  from  the  lymphatic  glands,  which  have  been 
termed  conglobate.  Those  glands  constitute  the  viscera,  and  are 
formed  by  a number  of  nerves  and  vessels  of  all  kinds,  arrang- 
ed in  fasciculi  and  united  by  cellular  membrane.  A membrane 
peculiar  to  the  organs,  or  supplied  by  those  which  line  the  cavi- 
ties in  which  they  are  contained,  covers  their  outer  part,  and 
insulates  them  from  the  neighbouring  organs. 

The  intimate  arrangement  of  the  different  parts  which  form 
the  secretory  glands,  the  disposition  of  the  arteries,  of  the 
veins  and  nerves,  and  the  manner  in  which  the  lymphatics  and 
excretory  ducts  arise  from  them,  have  given  rise  to  endless  dis- 
cussions, and  formed  the  basis  of  former  physiological  theories. 
What  follows  may  be  considered  as  a correct  abstract  of  what  is 
known  on  the  subject. 

The  respective  arrangement  of  the  similar  parts  {^parties 
similaires*^  which  enter  into  the  structure  of  the  glands  and 
which  form  their  proper  substance,  or  parenchyma,!  is  different 
in  each  of  them;  this  explains  their  differences,  in  the  double 
relation  of  their  properties  and  their  uses.  The  arteries  are  not, 

• By  parties  similaires,  the  author  means  the  simple  elementary  tissues. — 
See  the  preliminary  discourse,  page  19. 

f Do  the  different  appearances  of  the  substance  of  glandular  bodies  depend 
on  the  different  manner  in  which  the  similar  parts  cross  each  other,  and  on 
their  different  proportions  in  every  gland:  or  do  these  differences  of  colour,  of 
density,  by  means  of  which  we  so  readily  distinguish  the  substance  of  the 
liver  from  that  of  the  salivary  glands,  depend  on  the  existence  of  a peculiar 
tissue  in  each  organ^  This  question  cannot  be  answered,  in  the  present  state 
of  anatomy.  The  opinion,  however,  which  supposes  the  different  nature  of  the 
glands  to  depend  on  the  different  proportions  of  those  constituent  parts,  in 
each  of  them,  appears  the  most  probable. 


OP  THE  SECRETIONS, 


276 

as  Ruysch  thought,  immediately  continuous  with  the  excretory* 
ducts,  nor  are  there  intermediate  glands  between  those  vessels, 
as  Malpighi  conceived.  It  seems  more  probable,  that  each 
gland  has  its  own  peculiar  cellular  or  parenchymatous  tissue, 
in  the  areolae  of  which  the  arteries  pour  the  materials  of  the 
fluid  which  the  gland  prepares,  in  virtue  of  a power  which  is 
inherent  to  it,  and  which  is  its  distinguishing  character.  The 
lymphatics  and  the  excretory  ducts  arise  from  the  parietes 
of  those  cells;  and  these  two  kinds  of  vessels  absorb — the  one 
set,  the  secreted  fluid  which  they  carry  to  the  reservoirs  in 
%vhich  it  accumulates;  while  the  other  set  take  up  that  part  of 
the  fluid,  on  which  the  organ  has  not  completed  its  action;  in 
other  words,  the  residue  of  secretion. 

'KCW 111.  Of  accidental  secretions.  If  one  wished  to  extend 
the  idea  attached  to  the  term  secretion,  one  might  say,  that 
every  thing,  in  the  living  economy,  is  performed  by  means 
of  the  secretions.  What  is  digestion,  but  the  separation  or 
secretion  of  the  chylous  or  nutritive  parts  of  aliments,  from 
their  faecal  or  excrementitious  portion?  Do  not  the  absorbents 
concur  in  this  secretion?  May  they  not  be  considered  as  the 
excretory  ducts  of  the  digestive  organ  which  acts  on  the  aliment, 
in  the  same  manner  as  a secretory  gland  acts  on  the  blood  that 
contains  the  materials  of  the  fluid  to  be  elaborated?  Respiration, 
as  we  have  already  seen,  is  but  a double  secretion  which  the 
lungs  perform,  on  the  one  hand,  of  the  oxvgeu  contained  in  the 
atmospherical  air,  and  on  the  other  hand,  of  the  htdrogen  and 
carbon,  of  the  water,  and  of  the  other  heterogeneous  principles 
contained  in  venous  blood;  and,  as  will  be  shown  in  the  ensuing 
chapter,  nutrition  is  but  a peculiar  mode  of  secretion  which  is 
different  in  every  organ.-  It  is,  therefore,  only  after  a series  of 
very  delicate  and  very  complicated  separations  and  analyses, 
that  the  organs  are  enabled  to  make  extraneous  substances 
undergo  such  a change  of  composition,  as  to  render  them  fit  for 
their  growth  and  reparation. 

There  is  every  reason  to  believe,  that  the  phenomena  of  sen- 
sation and  of  motion,  by  means  of  which  man  keeps  up,  with 
surrounding  objects,  the  relations  necessary  to  his  existence, 
are  the  result  of  the  secretions  of  which  the  blood  furnishes  the 
materials  prepared  by  the  brain,  by  the  nerves,  by  the  muscles. 


OF  THE  SECRETIONS. 


277 

&c.  A plant  separates  from  the  earth,  in  which  its  roots  are 
buried,  the  juices  which  it  requires;  these  juices  constitute  the 
sap,  which,  after  being  filtered  through  a multitude  of  canals, 
supplies  the  different  secretions  whose  products  are  leaves, 
blossoms  and  fruits,  with  gums,  essential  oils,  and  acids.  All 
organized  bodies  are,  therefore,  so  many  laboratories,  in  which 
numerous  instruments  spontaneously  perform  various  composi- 
tions, decompositions,  syntheses,  analyses,  which  may  be  consi- 
dered as  so  many  secretions  from  the  common  fluid. 

If  we  confine  ourselves  in  our  view  of  the  subject,  and  limit 
our  attention  to  man,  the  principal  and  almost  the  sole  object  of 
our  study,  we  shall  see  that  the  different  secretions  that  may 
take  place  in  him,  are  extremely  numerous  and  varied,  and  that 
a change  in  the  condition  of  one  of  his  organs,  is  sufficient  to 
enable  it  to  secrete  a new  fluid.  Hence  inflammation  in  any 
gland,  is  sufficient  to  alter  the  secretion  of  the  organ  that  is 
affected.  A portion  of  adipose  tissue,  on  being  affected  with 
inflammation,  shall  secrete,  instead  of  fat,  a whitish  fluid  known 
by  the  name  of  pus.  The  pituitary  membrane,  when  inflamed, 
furnishes  a mucus  more  fluid  and  more  abundant,  and  w'hich, 
by  degrees,  returns  to  its  natural  state,  in  proportion  as  the 
coryza  goes  off;  the  serous  membranes,  as  the  pleura  and  the 
peritoneum,  will  allow  a greater  quantity  of  serum  of  a more  al- 
buminous quality,  sometimes  even  coagulable  lymph,  to  exude; 
at  other  times,  inflammation  causes  an  adhesion  of  their  conti- 
guous surfaces,  and  as  the  inflammatory  state  varies  in  intensity, 
the  accidental  secretion  will  likewise  vary  as  to  its  qualities; 
thus,  the  phlegmonous  inflammation  which  should  furnish,  on 
terminating  in  suppuration,  a whitish  fluid,  thick,  consistent, 
and  almost  without  smell,  will  give  out,  if  the  process  is  not 
sufficiently  active,  a serous  pus,  colourless,  and  without  con- 
sistence, &c.  For  in  the  same  reason,  the  blood  vessels  of  the 
uterus  pour  out,  in  some  women,  a dark  coloured  blood,  while 
in  others,  they  give  out  a mere  serosity,  very  slightly,  if  at  all, 
tinged  with  blood.* 

* To  these  examples  of  morbid  secretions,  others  may  be  added,  even 
more  remarkable,  as  the  virus  in  rabies  canina,  in  syphilis,  the  small  pox,  &c. 
By  some  animals  the  power  is  possessed  of  secreting  naturally  the  most  virulent 
, poisons. 


OP  THE  SECRETIONS. 


278 

The  menstrual  discharge,  in  women,  is  the  product  of  a real 
secretion  of  the  arterial  capillaries  of  the  uterus,  in  the  same 
manner  as  those  vessels  in  the  pituitary  membrane,  the  mem- 
brane which  lines  the  bronchise,  the  stomach,  the  intestines,  the 
bladder,  &c.  pour  out  blood  abundantly,  or  allow  its  transuda- 
tion, when  irritation  is  determined  to  those  parts;  in  hemorrhage 
from  the  nose,  in  bleeding  from  the  lungs,  or  from  the  stomach, 
when  the  vessels  are  not  ruptured  by  external  violence.  Apo- 
plexy itself,  whether  sanguineous  or  serous,  may,  in  several 
instances,  be  ranked  among  those  secretory  evacuations,  the 
quality  of  which  varies,  according  to  the  energj’  of  the  capilla- 
ries which  produce  it.  On  opening  dead  bodies,  one  frequently 
meets  with  a collection  of  blood  in  the  ventricles  of  the  brain, 
in  persons  who  have  died  from  apoplexy,  yet  the  most  careful 
examination  does  not  enable  one  to  detect  the  slightest  lacera- 
tion or  rupture  in  the  veins  or  in  the  arteries  within  the  skull.* 

poisons.  Of  this  description  are  many  of  the  reptiles,  but  especially  the  viper, 
the  rattle-snake,  Sec.  There  are  others  again,  which  are  distinguished  by  secre- 
tions peculiar  to  themselves.  For  instance,  the  ant  pours  out  a fluid  of  a specific 
acid  nature,  the  scuttle  fish  a dark  liquor,  and  the  skunk  a urine  so  offensive 
as  to  become  a means  of  protection,  repelling,  by  its  stench,  many  an  as- 
sailant.— Ed. 

* That  the  menstrual  discharge  results  from  a secretory  action  of  the  uterus, 
is  a doctrine  which  we  early  adopted,  and  have  taught  in  our  lectures  for  tlie 
last  ten  years.  Every  other  hypothesis  on  the  subject  is  totally  irreconcileable 
with  facts,  and  repugnant  to  the  laws  of  the  animal  economy.  The  crude 
speculations  of  former  times,  respecting  this  operation,  may,  indeed,  be 
considered  as  discarded.  Does  any  one,  for  instance,  whose  knowledge  has 
kept  pace  with  the  improvements  of  physiology,  now  entertain  the  notion 
of  lunar  influence,  of  fermentation  of  venereal  appetite,  of  general  plethora  or 
local  congestion,  &c.  fcc.?  The  leading  arguments,  in  defence  of  this  doctrine, 
may  be  thus  enumerated. 

1.  That  the  uterus,  in  its  villous  and  vascular  structure,  resembles  a gland, 
and  also  in  its  diseases,  being  equally  liable  to  scirrhus,  cancer,  &c.  &c. 

2.  That,  like  other  secretory  organs,  blood  is  very  copiously  diffused  through 
it. 

3.  That,  by  the  arrangement  of  its  vessels,  it  is  evidently  desigpied  that  the 
circulation  should  be  retarded  for  the  purpose  of  secretion.  The  arteries  are  not 
only  exceedingly  convoluted,  but  they  are  larger,  and  with  thinner  coats  than 
their  corresponding  veins. 

4.  That,  in  common  with  other  secretions,  menstruation  is  often,  at  first, 
imperfectly  performed,  and  is  subject  afterwards  to  vitiation  and  derange- 
ment. 


OF  THE  SECRETIONS, 


279 

The  nerves,  of  which  there  is  always  a certain  number  in  the 
structure  of  the  secretory  organs,  and  which  are  principally 


ment.  In  the  beginning  the  discharge  is  commonly  thin,  colourless,  and  defi. 
cient,  and  recurs  at  protracted  and  irregular  intervals.  In  some  of  these  par- 
ticulars, it  is  analogous  to  the  seminal  secretion. 

5.  That,  in  many  of  the  inferior  animals,  during  the  season  of  venereal 
incalescence,  there  is  an  uterine  effusion  which  is  undoubtedly  a secretion. 
This  answers,  seemingly,  the  same  end  as  menstruation,  namely,  giving  to  the 
uterus  an  aptitude  for  conception.  Though  this  fluid  generally  differs  from  the 
menses  in  complexion,  yet,  in  some  instances,  they  are  precisely  similar. 
Whenever  the  venereal  desire  suffers  a violent  exacerbation  from  restraint  or 
other  causes,  the  discharges  in  these  animals  become  red.  This  has  been  more 
especially  remarked  in  bitches  kept  from  the  male. 

6.  That,  when  the  menses  are  suppressed,  they  cannot  be  restored  by- 
inducing  plethora,  nor  the  flow  be  checked  by  blood-letting,  or  any  other 
means  of  depletion.  Besides,  no  vicarious  discharge  relieves  the  symptoms  of 
suppression.  Do  not  these  facts  very  unequivocally  proclaim  ihe  existence  of 
a secretory  function? 

Lastly,  That  the  menses  are  a fluid  sui  generis,  or  at  least  varying  essentially 
from  blood;  having  neither  its  colour,  nor  odour,  nor  coagulability,  and,  on  che- 
mical analysis,  present  different  results.  Let  us  ask,  if  the  menstrual  fluid  be 
not  blood,  what  is  it?  To  the  objection,  which  has  sometimes  been  urged,  that 
the  uterus  is  not  sufficiently  glandular  for  the  office  alleged,  it  may  be,  I 
think,  very  satisfactorily  replied,  that  there  is  hardly  a viscus  or  surface  of  the 
body  which  is  not  competent  to  this  purpose.  It  would  rerdly  seem  that  no 
operation  of  the  animal  economy  requires  a less  complex  apparatus.  Of  what, 
indeed,  does  a gland  consist,  except  a congeries  of  vessels?  Even  the  most 
perfect  of  the  secretions  are  accomplished  by  this  simple  contrivance.  If  a few 
vessels,  “ creeping  through  the  coats  of  the  stomach,”  can  secrete  the  gastric 
liquor,  why  may  not  the  infinitely  more  glandular  organization  of  the  uterus 
elaborate  the  menstrual  fluid?  As  yet  we  know  of  no  glandular  structure  in 
vegetables,  they  containing  only  tubes  or  vessels,  through  which  the  fluids 
circulate.  Notwithstanding,  however,  the  want  of  glands,  we  find  the  sap  of 
plants  converted  into  oil,  mucilage,  acids,  &c.  No  stronger  proof  can  certainly 
be  required  of  the  extreme  simplicity  of  the  organs  by  which  the  secretory 
transformations  are  effected. 

Who  originally  suggested  the  theory  of  secretion  we  have  not  been  able 
to  ascertain.  It  has  very  generally  been  ascribed  to  the  celebrated  Mr. 
Hunter;  but  the  evidence  of  his  claims  to  it  is  exceedingly  slender.  The  only 
trace  of  it,  which  we  can  discover  in  his  writings,  is  a vague  expression  in 
a paragraph  of  his  Treatise  on  the  Blood.  Afterwards,  however,  he  furnished 
an  extract  from  his  lectures  to  be  published  in  Johnson’s  Midwifery,  as  exhi- 
biting more  fully  his  notion  respecting  tliis  function.  Speaking  of  the  death  of 
the  blood  from  lightning,  and  other  sudden  causes,  he  includes  the  catamenia 

among 


280 


OF  THE  SECRETIONS. 


branches  of  the  great  symphathetic*  nerves,  terminating  ia 
various  ways,  in  their  substance,  give  to  each  of  them  a peculiar 
sensibility,  by  means  of  which  they  discover  in  the  blood  which 
the  vessels  bring  to  them,  the  materials  of  the  fluid  which  they 
are  destined  to  secrete,  and  these  they  appropriate  to  themselves 
by  a real  selection.  Besides,  the  nerves  communicate  to  them  a 
peculiar  mode  of  activity,  the  exercise  of  which  makes  those 
separated  elements  undergo  a peculiar  composition,  and  bestows 
on  the  fluid,  which  is  the  product  of  it,  specific  qualities  always 
bearing  a certain  relation  to  the  mode  of  action  of  which  it  is 
the  result.  Thus,  the  liver  seizes  the  materials  of  the  bile  con- 
tained in  the  blood  of  the  vena  portae,  elaborates,  combines 
those  materials,  and  converts  them  into  bile,  an  animal  fluid, 
distinguishable  by  peculiar  characteristic  properties  subject  to 
certain  variations,  according  as  the  blood  contains,  in  different 
proportions,  the  elements  of  which  it  is  formed;  according  as 
the  gland  is  more  or  less  disposed  to  retain  them,  and  to  blend 
them  together.  The  qualities  of  the  bile  depending  on  a con- 
currence of  all  these  circumstances,  must  present  as  many  dif- 
ferences as  the  blood  which  contains  its  elements,  and  the  liver 
may  present  varieties,  with  regard  to  the  composition  of  the 
former  and  to  the  activity  of  the  latter.  Hence  the  many 
changes  in  the  qualities  of  the  fluid,  the  slightest  of  which, 
not  affecting  the  health,  escape  observation,  while  those  changes 
which  are  greater  and  which  disorder  the  natural  order  of  the 
functions,  show  themselves  in  diseases  of  which  they  may  be 

among  the  illustrations  of  bis  reasonings.  “ The  blood,”  says  he,  “ discharged 
“ in  menstruation  is  neither  similar  to  blood  taken  from  a vein  of  the  same 
“ person,  nor  to  that  extravasated  by  an  accident  in  any  other  part  of  the 
“ body:  but  is  a species  of  blood  changed,  separated,  or  thrown  off  from  the 
“common  mass  by  an  action  of  the  vessels  of  the  uterus,  in  a process  similar 
“ to  secretion,  by  which  action  the  blood,  having  lost  its  living  principle,  does 
“ not  coagulate,”  &c. 

“ The  blood,”  says  HaHer,  “ is  brought  to  the  womb  in  greater  quantity, 
“and  more  quickly,  through  its  lax  and  ample  arteries,  and  on  account  of  the 
“ rigidity  and  narrowness  of  the  veins,  it  returns  -with  difficulty.” — Ed. 

* They  are  likewise  given  off,  in  great  number,  from  the  cerebral;  thus,  the 
salivary  glands  receive  from  the  seventh  pair,  from  the  maxillary  nerve,  from 
the  fifth  pair  and  from  the  cervical  nerves,  a number  of  nerves  tliat  will  appear 
very  great,  if  the  bulk  of  those  glands  is  considered. 


OF  THE  SECRETIONS. 


281 

considered  as  the  effect,  and  at  other  times,  as  the  cause.  These 
changes  in  the  condition  of  the  bile  (and  what  is  now  said  ap- 
plies to  almost  all  the  secretions  of  the  animal  economy),  are 
never  carried  so  far  as  to  make  the  bile  lose  all  its  distinguishing 
characters,  it  never  takes  on  the  qualities  belonging  to  another 
fluid,  it  never  resembles  semen,  urine,  or  saliva. 

The  secretory  glands  do  not  carry  on  an  uninterrupted  action; 
almost  all  of  them  are  subject  to  alternate  action  and  repose;  all, 
as  Bordeu  observed,  sleep  or  waken  when  irritation  affects  them 
or  their  neighbouring  parts,  and  determines  their  immediate  or 
sympathetic  action.  Thus,  the  saliva  is  more  plentifully  secreted 
during  mastication;  the  gastric  juice  is  poured  within  the  sto- 
mach only  while  digestion  is  going  on;  when  the  stomach  is 
emptied  of  food  the  secretion  ceases,  and  is  renewed  when  the 
presence  of  food  again  excites  a sufficient  degree  of  irritation. 
The  bile  flows  more  abundantly,  and  the  gall  bladder  frees 
itself  of  that  which  it  contains,  while  the  duodenum  is  filled  by 
the  chymous  mass. 

When  a secretory  organ  is  in  action,  it  determines  the  motion 
of  the  parts  in  its  vicinity,  or,  as  Bordeu  expresses  it,  within  its 
atmosphere.  A part  is  said  to  belong  to  the  department  of  a 
certain  gland,  when  it  partakes  in  the  motion  affecting  the  latter, 
during  the  process  of  secretion,  or  when  it  is  employed  in  func- 
tions subservient  to  that  of  the  gland;  these  departments  are  of 
different  extent,  according  to  the  importance  of  the  action  of  the 
gland.  Thus,  one  may  say,  that  the  spleen  and  most  of  the  viscera 
of  the  abdomen  are  of  the  department  of  the  liver,  since  they 
receive  from  it  the  blood  on  which  they  are  to  act.  The  liver  is 
also  comprised  in  the  sphere  of  activity  of  the  duodenum,  since 
the  distention  of  that  intestine  irritates  it,  determines  a more 
copious  flow  of  its  fluids,  and  a more  abundant  secretion  of  bile. 

C.  The  blood  which  is  sent  to  a secretory  gland,  before 
reaching  it,  undergoes  preparatory  changes,  which  dispose  it  to 
furnish  the  materials  of  the  fluid  which  is  to  be  separated  from 
it.  We  have  seen,  in  treating  of  digestion,  how  the  blood,  which 
the  vena  portae  sends  to  the  liver,  is  fitted  for  the  secretion  of 
bile.  There  can  be  no  doubt  that  the  portion  of  blood  which  is 
carried  to  the  testicles,  by  the  long,  slender,  and  tortuous  sper- 

2 N 


OF  THE  SECRETIONS. 


282 

matic  arteries,  undergoes  changes  which  bring  it  nearer  to  the 
seminal  fluid. 

The  rapiditv  with  which  the  blood  flows  into  an  organ,  the 
length,  the  diameter,  the  direction,  the  angles  of  its  vessels,  the 
arrangement  of  their  extreme  ramifications,  which  may  be  stel- 
lated, as  in  the  liver;  in  fasciculi,  as  in  the  spleen;  convoluted, 
as  in  the  testicles,  &c.;  are  circumstances  which  should  be  taken 
into  account  in  the  study  of  each  secretion,  since  all  have  some 
influence  on  the  nature  of  the  fluid  secreted,  and  on  the  manner 
in  which  the  secretion  is  effected. 

The  fluid  which  lubricates  the  whole  extent  of  the  moveable 
surfaces  by  which  the  bones  of  the  skeleton  are  articulated  to- 
gether, is  not  exclusively  prepared  by  the  membranous  capsules 
which  envelop  the  articulations.  A number  of  reddish  coloured 
cellular  substances,  placed  in  their  vicinity,  co-operate  in  the 
secretion.  Though  these  parts,  which  were  long  considered  as 
synovial  glands,  do  not  completely  resemble  the  conglomerate 
glands,  and  although  no  glandular  bodies  nor  excretory  ducts 
can  be  demonstrated  in  them,  they  cannot,  however,  but  be  con- 
sidered as  fulfilling,  to  a certain  degree,  the  same  functions;  and 
one  must  admit  that  they  are  of  some  utility  in  the  secretion  of 
the  synovia.  They  are  always  met  with;  their  extent  and  bulk 
are  always  proportioned  to  the  extent  of  the  articular  surfaces, 
and  to  the  frequency  of  motion  in  the  joints  near  whTchthey  are 
situated.  They  are  found  in  all  animals;  pale  and  light  coloured 
in  those  which  have  been  long  at  rest;  red,  highlv  vascular,  and 
bearing  the  marks  of  a kind  of  inflammatory  diathesis  in  those 
which  have  been  compelled  to  violent  exercise;  as  the  oxen 
which  are  brought  to  Paris  from  distant  provinces,  and  the  wild 
animals  which  have  been  hunted.  In  anchylosis  they  are  less 
yed  and  of  greater  consistence  than  in  a healthy  state. 

When,  from  the  irritation  attending  friction,  the  fluids  are 
determined  towards  an  articulation  which  is  in  motion,  do  they 
not  then,  by  passing  through  those  glanclulo-cellular  bodies,  un- 
dergo a peculiar  modification,  which  renders  them  fitter  for  the 
secretion  of  synovia.  This  would  not  be  the  only  instance  in  the 
human  body  of  parts  whose  action  is  but  secondary,  and  con- 
nected with  that  of  other  organs  principally  engaged  in  a secret 
lion,  whose  materials  are  contained  in  the  blood  which  passes 


OF  THE  SECRETlOTfS. 


283 

through  them.  It  will  be  urged,  no  doubt,  that  this  preparatory- 
apparatus  is  not  met  with  in  the  neighbourhood  of  the  great 
cavities;  but  it  should  be  recollected  that  the  chemical  composi- 
tion and  the  uses  of  the  synovia,  are  not  precisely  the  same  as 
those  of  the  fluids  secreted  by  the  pleura  or  the  peritoneum;  and 
that,  besides,  the  analogy  between  two  objects  does  not  consti- 
tute their  identity.  The  human  mind  being  naturally  indolent, 
loves  to  discover  analogies  that  support  it  in  its  weakness,  and 
that  may  save  it  the  trouble  of  seeking  points  of  difference.  I am 
aware  that  to  prove  that  the  mechanism  of  the  synovial  secre- 
tion, which  exactly  resembles  that  of  the  #uid  which  moistens 
the  inside  of  the  great  cavities,  and  requires  like  it  but  a simple 
membranous  apparatus,  it  is  customary  to  repeat  in  every  pos- 
sible way,  that  nature  is  scanty  in  her  means,  and  lavish  in  her 
results;  that  she  produces  from  the  same  cause  a variety  of 
different  effects.  See.  But  without  pointing  out  the  manifest  ab- 
surdity of  admitting  metaphysical  arguments  in  the  natural 
sciences,  is  it  not  much  more  reasonable  to  acknowledge  with 
philosophers,  that  the  primitive  cause  may  vary  in  many  ways, 
and  that  its  innumerable  modifications,  whence  arise  the  differ-' 
ence  in  the  effects,  exceed  the  limited  powers  of  our  under- 
standing? 

Cl.  When  a gland  is  irritated  it  becomes  a centre  of  fluxion, 
towards  which  the  fluids  are  determined  from  every  part;  it 
swells,  hardens,  contracts,  is  in  a kind  of  state  of  erection,  bends 
on  itself,  and  acts  on  the  blood  conveyed  by  its  vessels.  Secre- 
tion, depending  on  the  peculiar  and  inherent  power  of  the  glan- 
dular organ,  is  promoted  by  the  slight  motion  which  it  receives 
from  the  neighbouring  muscles.  The  gentle  pressure  of  those 
parts  on  the  glandular  organs,  is  sufficient  to  keep  up  their  ex- 
citement, and  to  assist  in  the  separation  and  excretion  of  the 
fluid.  Bordeu,  in  his  excellent  work  on  the  glands  and  on  their 
action,  has  shown  that  it  is  not  in  consequence  of  the  compres- 
sion which  is  produced  on  them  by  the  neighbouring  muscles, 
that  they  part  with  the  fluid  they  have  prepared;  that  physio- 
logists were  therefore  very  much  in  the  wrong  in  saying  that 
the  excretion  of  a fluid  consisted  merely  in  its  expression, 
and  in  comparing,  under  that  point  of  view,  the  glands  to  spunges 
soaked  with  a fluid,  which  they  give  out  on  being  squeezed^ 


OF  THE  SECRETIONS. 


284 

The  excretory  ducts  of  organs  absorb  or  reject  the  secreted 
fluid,  according  as  it  affects  their  inhalent  mouths;  these  canals 
partake  in  the  convulsive  state  of  the  gland,  undergo  a degree 
of  erection,  and  contract  on  the  fluid  to  expel  it.  Thus,  the  saliva 
starts  from  the  parotid  duct  at  the  sight,  or  on  the  recollection 
of  food  that  has  been  longed  for:  thus,  the  vesiculae  seminales 
and  the  urethra,  (for  the  reservoirs  in  which  the  fluids  lie  some 
time  before  being  expelled,  may  be  considered  as  forming  a 
part  of  the  excretory  ducts,)  contract,  become  straighter,  and 
lengthen  themselves  to  force  to  a distance  the  spermatic  fluid. 

The  thin  and  transparent  ureters  of  fowls  have  been  seen  to 
contract  on  the  urine,  which  in  these  animals  concretes  on  the 
slightest  stagnation. 

After  remaining  a certain  length  of  time  in  that  state  of  ex- 
citement, the  glands  relax,  their  tissue  collapses,  the  juices  cease 
to  be  conveyed  to  it  as  plentifully,  they  fall  into  a state  of  repose 
or  sleep,  which  restores  their  sensibility,  exhausted  by  too  much 
action.  It  is  well  known  that  a gland  over-stimulated,  becomes, 
like  any  other  part,  insensible  to  the  stimulus,  the  continued 
application  of  which  parches  and  exhausts  it. 

From  what  has  just  been  said  relative  to  the  mechanism  of 
the  secretions,  it  will  be  seen  that  this  function  may  be  divided 
into  three  very  distinct  periods;  1st,  that  of  irritation,  charac- 
terized by  the  growth  of  the  vital  properties,  and  by  the  more 
copious  accession  of  the  fluids,  the  necessary  consequence  of 
that  excitement;  2d,  the  action  of  the  gland;  that  is,  its  secre- 
tion, properly  so  called;  3d,  lastly,  the  action  by  which  the  or- 
gan parts  with  the  fluid  which  it  has  prepared;  this  is  the  last 
process;  it  is  called  excretion,  and  is  promoted  by  the  action  of 
the  neighbouring  parts.  The  determination  of  fluids  to  the  part, 
the  secretion  and  excretion  succeed  each  other;  they  are  pre- 
ced  by  the  excitement  which  is  the  primary  cause  of  all  the 
subsequent  phenomena.  The  circulation  is  at  first  excited,  more 
blood  is  sent  into  the  part,  and  penetrates  into  the  tissue  of  the 
gland.  Dr.  Murat,  who  has  had  occasion  to  open  a considerable 
number  of  old  men  that  died  at  the  Bicetre,  and  who  were 
known  to  be  great  smokers  of  tobacco,  has  uniformly  observed 
that  their  parotid  glands,  continually  called  into  action  by  that 
habit,  were  larger  than  in  those  who  were  not  given  to  it,  and 


OF  THE  SECRETIONS.  285 

that  they  were  remarkably  red,  in  consequence  of  the  blood  with 
which  they  were  constantly  injected. 

What  is  the  office  of  the  nerves  in  the  act  of  secretion?  What 
share  has  the  nervous  influence  in  the  elaboration  of  the  fluids 
furnished  by  the  glandular  organs?  All  the  glands  which  receive 
their  nerves  from  the  system  of  animal  life,  such  as  the  lachry- 
mal and  salivary  glands,  appear  in  certain  cases  to  receive  from 
the  brain  the  secretory  excitation.  The  influence  of  the  imagi- 
nation is  sufficient  to  determine  it;  thus,  we  shed  involuntary 
tears  when  the  mind  is  taken  up  with  painful  thoughts;  and  the 
mouth  fills  with  saliva  on  the  recollection  of  a grateful  meal.  In 
such  cases,  the  influence  of  the  nerves  on  the  process  of  secre- 
tion is  indisputable;  it  is  not  so,  however,  with  the  conglomerate 
glands  that  receive  their  nerves  from  the  great  sympathetics.  The 
secretion  of  the  kidneys,  of  the  liver,  and  of  the  pancreas,  appears 
less  influenced  by  affections  of  the  mind;  the  brain,  besides,  has 
no  immediate  connection  with  these  glands;  their  nerves  are 
almost  entirely  given  off  by  the  great  sympathetics;  the  kidneys 
in  particular,  receive  no  nerves  from  the  brain  or  from  the  spi- 
nal marrow:  hence  the  secretion  of  urine  seems  more  than  any 
other  to  be  independent  of  the  nervous  influence. 

The  great  number  of  secretory  organs,  constantly  engaged  in 
separating  various  secretions  from  the  mass  of  the  fluids,  would 
soon  exhaust  it  if  the  calculations  of  physiologists  of  the  amount 
of  what  a gland  is  capable  of  secreting,  were  not  manifestly  ex- 
aggerated. In  fact,  if  we  admit  with  Haller,  that  the  mucous 
glands  of  the  intestinal  canal  secrete,  in  twenty-four  hours,  eight 
pounds  of  mucus;  that,  in  the  same  space  of  time,  the  kidneys 
secrete  four  pounds  of  urine;  that  the  same  quantity  is  lost  by 
the  insensible  perspiration;  and  again,  as  much  by  the  pulmo- 
nary exhalation;  there  will  be  lost,  daily,  twenty  pounds  of  fluids,, 
almost  entirely  excrementitious;  for  we  do  not  include  in  that 
calculation,  the  bile,  the  tears,  nor  the  saliva  and  pancreatic 
fluid,  which,  in  part,  returns  into  the  blood  after  being  separated 
from  it;  nor  the  serum  which  moistens  the  internal  surfaces,  and 
which  is  purely  recrementitious. 

This  exaggeration  in  the  calculation  of  the  fluids  which  are 
daily  poured  out  by  the  different  emunctories,  is  to  be  attributed 
to  the  circumstance  of  having  taken  the  maximum  of  each  secre- 


ON  THE  SECRETIONS. 


286 

tion,  without  considering  that  they  mutually  supply  each  othefi 
so  that,  when  less  urine  is  voided,  the  quantity  of  perspiration 
is  greater,  and  vice  versa.  It  is  very  well  known,  that  a violent 
diarrhoea  is  frequently  the  consequence  of  sudden  cold  applied 
to  the  skin;  the  fluids,  at  once  repelled  towards  the  intestinal 
canal,  having  to  pass  through  the  mucous  glands  whose  action 
is  greatly  increased. 

CII.  It  has  been  customary  to  enumerate  among  the  glands, 
certain  bodies  which  have  truly  a glandular  appearance,  but  the 
uses  of  which  are  yet  unknown.  Thus,  the  thyroid  and  thymus 
glands,  which  are  parenchymatous  organs  destitute  of  excretory 
ducts,  though  receiving  many  vessels  and  some  nerves,  do  not 
appear  to  secrete  any  fluid.  But  may  not  the  blood,  which  is  con- 
veyed so  plentifully  to  the  thyroid  gland,  undergo  nevertheless 
certain  changes,  though  we  may  not  be  able  to  discover  what 
they  are.  Besides,  may  not  the  lymphatics  perform  the  office  of 
excretory  ducts  and  convey  back  again  immediately  into  the 
mass  of  the  blood,  the  fluid  which  has  undergone  changes  in  the 
glandular  body?  The  capsulae  renales  are  in  the  same  condition: 
they  have,  however,  in  addition,  an  internal  reservoir,  a kind  of 
lacuna,  whose  parietes  are  smeared  with  a viscid  and  brown 
coloured  substance  secreted  by  the  capsule,  and  which,  doubt- 
less, is  conveyed  into  the  mass  of  the  blood  by  the  lymphatics 
arising  from  the  parietes  of  its  internal  cavity. 

cm.  Of  the  secretion  of  adeps  within  the  cellular  tissue. 
This  soft  tissue,  which  is  diffused  over  the  whole  body,  and  af- 
fords a covering  to  all  our  organs,  is  of  use  not  merely  in  sepa- 
rating them  from  one  another,  and  in  connecting  together  the 
different  parts;  it  is  besides,  the  secretory  organ  of  the  adipose 
substance,  a semi-concrete  oily  animal  substance  which  is  found 
in  almost  every  part  of  the  body,  deposited  in  its  innumerable 
cells.  The  membranous  parietes  of  these  small  cellular  cavities 
are  supplied  by  numerous  minute  arteries,  in  which  the  adeps  is 
separated;  it  is  conveyed  by  its  specific  light  weight  to  the  cir- 
cumference of  the  column  of  blood  in  the  vessels,  and  transudes 
through  the  pores  in  their  parietes.  Its  quantity  and  consistence 
vary  in  different  parts  of  the  body,  and  in  different  persons; 
there  is  situated  below  the  skin  a thick  layer  of  cellular  sub- 
stance  (pannicule  graisseux);  it  is  found,  in  considerable  quan- 


OF  THE  SECRETIONS. 


287  • 

tity,  between  the  interstices  of  the  muscles,  along  the  blood-ves- 
sels, near  the  articulations  and  in  the  vicinity  of  certain  organs, 
as  the  eyes,  the  kidneys,  and  the  breasts.  That  which  fills  the 
bottom  of  the  orbit,  and  which  surrounds  the  eyeball,  is  softish 
and  almost  fluid;  that  which  envelops  the  kidneys  and  the  great 
joints  is,  on  the  contrary,  of  the  consistence  of  suet.  Between 
these  two  extremes,  there  are  many  gradations,  and  it  may  be 
said,  that  the  animal  oil  in  question,  is  not  exactly  the  same  in 
any  two  different  parts  of  the  body.  The  high  temperature  of  the 
human  body  maintains  it  in  a state  of  semi-fluidity,  as  may  be 
observed  in  surgical  operations. 

In  some  parts,  it  is  even  absolutely  fluid,'butits  nature  is  then 
observed  to  be  greatly  changed;  it  no  longer  contains  any  oily 
substance,  and  differs  but  little  from  a mere  aqueous  gelatine. 
Thus,  the  fluid  in  the  cellular  tissue  of  the  eye-lids,  of  the 
scrotum,  &c.  has  been  considered  by  several  physiologists  as  ab- 
solutelv  different  from  fat.  It  may  not  be  amiss  to  observe,  that 
the  laminse  of  the  cellular  tissue,  in  such  circumstances,  yield 
more  readily  to  extension,  present  a greater  surface,  form  mem- 
branous expansions,  and  circumscribe  cells  of  a considerable 
size,  so  that  the  differences  in  the  secretion  perfectly  coincide 
with  the  difference  of  structure.  It  may  further  be  observed, 
that  the  functions  of  the  eyelids  and  of  the  penis  required  that 
they  should  not  contain  any  fat.  Considerable  deformity,  when 
the  person  grew  fat,  would  have  been  the  consequence  of  the 
increased  bulk  of  these  parts,  and  besides,  the  folds  of  the  skin 
would  not  have  that  free  motion  which  their  functions  require. 
No  real  adeps  is  ever  found  within  the  skull,  and  the  utility  of 
this  condition  is  very  obvious.  To  how  many  dangers  would 
not  life  have  been  exposed,  if  a fluid,  so  varying  in  quantitv, 
and  the  amount  of  which  may  be  trebled,  in  a very  short  spttce 
of  time,  had  been  deposited  into  a cavity  accurately  filled  bv 
an  organ  which  is  affected  by  the  slightest  compression? 

In  an  adult  male  of  moderate  embonpoint.,  the  proportion  of 
adeps  is  about  one  twentieth  of  the  weight  of  the  whole  body;  it 
is  greater,  in  proportion,  in  children  and  in  females;  for,  its 
quantity  is  always  relative  to  the  energy  of  the  functions  of  as- 
similation. When  digestion  and  absorption  are  performed  with 
great  activity,  fat  accumulates  within  the  cellular  substance;  and 


OF  THE  SECRETIONS. 


288 

if  it  be  considered  that  it  is  but  imperfectly  animalized,  that  it 
bears  the  most  striking  analogy  to  the  oils  extracted  from  plants; 
that  it  contains  very  little  azote  and  much  hydrogen  and  carbon, 
like  all  other  oily  substances,  since  on  distillation  it  is  decom- 
posed, and  yields  water  and  carbonic  acid,  with  a very  small 
quantity  of  ammonia;  that  its  proportions  are  very  variable,  and 
may  be  considerably  increased  or  diminished,  without  manifestly 
impairing  the  order  of  the  functions;  that  animals  that  spend  a 
great  part  of  their  life  without  eating,  seem  to  exist  during  their 
torpid  state,  on  the  fat  which  they  have  previously  accumulated 
in  certain  parts  of  their  body;*  one  will  be  led  to  think,  that  the 
state  of  fat  is,  to  a portion  of' the  nutritive  matter  extracted 
from  the  food,  a kind  of  intermediate  state,  through  which  it 
has  to  pass  before  it  can  be  assimilated  to  the  animal  whose 
waste  it  is  destined  to  repair.  Animals  which  live  on  grain  and 
vegetables,  are  always  fatter  than  those  which  live  exclusively  on 
flesh.  Their  fat  is  consistent  and  firm,  while  that  of  carnivorous 
animals  is  almost  completely  fluid. 

A corpulent  man,  on  having  his  diet  suddenly  reduced,  sen- 
sibly becomes  thinner  in  a very  short  time:  the  bulk  and  weight 
of  his  body  diminishes  from  the  absorption  of  the  fat  which  sup- 
plies the  deficient  quantity  of  blood.  Adeps  may,  therefore,  be 
considered  as  a substance  in  reserve,  by  means  of  which,  not- 
withstanding the  small  quantity  of  food  and  its  want  of  nutri- 
tious qualities.  Nature  finds  wherewith  to  repair  the  daily  waste. 

CIV.  The  use  of  adeps  is  not,  as  has  been  stated  on  the  au- 
thority of  Macquer,  to  absorb  the  acids  that  are  formed  in  the 
animal  economy;  that  which  is  obtained  from  it  by  distillation, 
(the  sebaceous  acid)  is  a new  product  formed  by  the  combina- 
tion of  the  oxygen  of  the  atmosphere  with  the  hydrogen,  the 
carbon,  and  the  small  quantity  of  azote  which  it  contains.  The 
small  quantity  of  this  last  substance  nearly  constitutes  it  into  a 
vegetable  acid.  Fat  has  a considerable  affinity  for  oxygen,  and 

* Marmots  and  dormice  become  prodigiously  fat  during  the  autumn,  they 
then  take  to  their  holes  and  live  in  them  during  the  six  winter  months,  on  the 
fat  which  is  accumulated  in  all  their  organs.  There  is  most  fat  collected  in  the 
abdomen,  in  which  the  epiploon  forms  masses  of  a'considerable  size.  When, 
in  the  spring,  their  torpor  ceases,  and  they  awaken  from  their  sleep,  they  are, 
for  the  most  part,  xceedingly  emaciated. 


OF  THE  SECRETIONS. 


289 


by  combining  with  it,  turns  rancid,  after  remaining  some  time 
exposed  to  the  air.  It  deprives  metallic  oxides  of  a part  of  their 
oxygen,  and  likewise,  on  being  triturated  with  metallic  sub- 
stances, promotes  their  oxidizement.  In  proportion  as  it  absorbs 
oxygen,  its  density  increases;  thus  oil  becomes  concrete  by  com- 
bining with  oxygen,  and  fat  acquires  a consistence  almost  equal 
to  that  of  wax,  which  is  itself  a fatty  substance  highly  oxidized. 

Besides  the  principal  use  which  we  have  assigned  to  adeps, 
and  according  to  which,  the  cellular  system  may  be  looked  upon 
as  a vast  reservoir  in  which  there  is  deposited  a considerable 
quantity  of  nutritive  and  semi-animalized  matter,  this  fluid  an- 
swers several  purposes  of  secondary  utility.  It  preserves  the 
body  in  its  natural  temperature,  being  as  well  as  the  tissue  of 
the  cells  in  which  it  is  contained,  a very  bad  conductor  of  heat. 
Persons  who  are  excessively  corpulent,  scarcely  feel  the  most  se- 
vere cold;  the  animals  which  inhabit  northern  climates,  besides 
being  clothed  in  a thick  fur,  are  likewise  provided  with  a consi- 
derable quantity  of  fat.  The  fishes  of  the  fn.zcn  seas,  the  c-ta- 
ceous  animals  which  seldom  go  far  from  the  polar  regions,  all 
kinds  of  whales,  are  covered  with  fat,  and  have  likewise  a c >n= 
siderable  quantity  within  their  body.  By  its  unctuous  qualities, 
fat  promotes  muscular  contraction,  the  motion  of  the  difl'erent 
organs,  the  free  motion  on  each  other  of  the  different  surfaces; 
it  stretches  and  supports  the  skin,  fills  vacuities  and  gives  to 
our  limbs  those  rounded  outlines,  those  elegant  and  graceful 
forms  peculiar  to  the  female  body.  Lastly,  it  envelops  and 
covers  over  the  extremities  of  the  nerves,  diminishes  their 
susceptibility,  which  is  always  in  an  inverse  ratio  of  the  embon^ 
pointy  which  induced  a physician  of  merit  to  say,  that  the  ner- 
vous tree,  planted  in  the  adipose  and  cellular  substance,  suffers, 
when  from  the  collapse  and  the  removal  of  that  tissue,  its 
branches  are  exposed,  in  an  unprotected  state,  to  the  action  of 
external  causes  as  injurious  to  them,  as  the  rays  of  the  sun  to  a 
plant  torn  from  its  native  soil.  It  is,  in  fact,  observed,  that  ner- 
vous people  are  exceedingly  thin,  and  have  an  excessive  degree  of 
sensibility.  Too  much  fat,  however,  is  as  injurious  as  too  small 
a quantity  of  it.  I have  seen  several  persons  whose  obesity  was’ 
such,  that  besides  being  completely  incapable  of  taking  the 
slightest  exercise,  they  were  in  great  danger  of  suffocation.  Re=- 

20 


OF  THE  SECRETIONS. 


290 

spiration  in  such  persons  is,  at  times,  interrupted  by  deep  sighs, 
and  their  heart,  probably  overloaded  with  fat,  expels,  with  diffi- 
culty, the  blood  within  its  cavities. 

CV.  According  to  modern  chemists,  the  use  of  fat  is  to  take 
from  the  system  a part  of  its  hydrogen.  When  the  lungs  or 
liver  are  diseased,  when  respiration  or  the  biliary  secretion  do 
not  carry  out  of  the  system  a sufficient  quantity  of  that  oily  and 
inflammable  principle,  fat  forms  in  a greater  proportion.  They 
appeal  to  the  result  of  the  experiment  of  shutting  up  a goose, 
whose  liver  is  to  be  fattened,  in  a confined  cage,  placed  in  a hot 
and  dark  situation,  and  in  gorging  it  with  paste,  of  which  it  eats 
the  more  greedily,  as  being  unabled  to  stir,  it  gratifies  its  incli- 
nation to  action,  by  exerting  the  organs  of  digestion.  Notwith- 
standing this  quantity  of  food,  the  bird  becomes  emaciated,  is 
affected  with  a kind  of  marasmus,  its  liver  softens,  grows  fatter, 
more  oily,  and  attains  an  enormous  size. 

This  experiment,  and  many  other  facts,  prove,  that  the  secre- 
tions from  which  analogous  products  are  formed,  may  mutually 
supply  each  other;  but  can  we  admit  the  chemical  theory  of  the 
use  of  fat,  when  we  recollect  that  frequently,  in  the  most  corpu- 
lent persons,  respiration  and  the  secretion  of  bile  are  performed 
with  great  freedom  and  with  no  difficulty;  while  the  difficult 
respiration  attending  pulmonary  consumption,  and  the  difficult 
flow  of  the  bile  from  an  obstruction  of  the  liver,  are  always  ac- 
companied with  complete  marasmus. 

Whatever  moderates  the  activity  of  the  circulatorj^  system, 
tends  to  bring  on  adipose  plethora.  Thus  an  inactive  state  of 
the  mind  and  body,  profuse  bleedings,  castration,  sometimes 
induce  obesity,  an  affection  in  which  the  cellular  tissue  appears 
affected  with  atony  and  undergoes  an  actual  adipose  infiltra- 
tion, which  may  be  compared  to  that  which  gives  rise  to  tu- 
mours called  steatomatous.  If  the  energy  of  the  heart  and 
arteries  is  too  great,  emaciation  is  always  the  consequence; 
when,  on  the  contrary,  the  sanguineous  system  is  languid,  there 
is  formed  a merely  gelatinous  fat  and  the  emhonpoint  is  a mere 
state  of  bloatedness. 

This  incompletely  formed  fluid,  which  distends  the  parts  in 
persons  of  a leucophlegmatic  habit,  is  but  an  imperfect  kind  of 
fat;  it  resembles  the  marrow  or  the  medullary  juice,  which  is 


OF  THE  SECRETIONS. 


^91 


merely  a very  liquid  fat,  whose  consistence  diminishes  when 
animals  become  lean.  Inclosed  within  the  cells  of  the  osseous 
tissue,  in  cavities  whose  sides  cannot  collapse,  and  whose  di- 
mensions must  always  remain  the  same,  the  marrow,  of  which 
they  are  never  free,  is  of  different  degrees  of  density;  and  what 
authors  say  of  its  diminished  quantity,  must  be  understood  as 
applying  to  the  diminution  of  its  consistence. 

C VI.  The  secretion  of  the  marrow  is,  like  that  of  the  fat,  a 
mere  arterial  transudation;  it  is  performed  by  the  medullary 
membrane,  which  is  thin,  transparent,  and  cellular,  which  lines 
the  inside  of  the  central  cavity  of  the  long  bones,  and  extends 
over  all  the  cells  of  their  spungy  substance.  The  medullary 
membrane,  when  in  a healthy  state,  does  not  give  any  marks 
of  relative  sensibility.  In  all  the  amputations  I have  perform- 
ed, and  they  have  not  been  few,  in  all  the  operations  of  the 
same  kind  at  which  I have  been  present,  whatever  the  bone 
was,  whether  it  was  divided  near  a joint  or  in  the  middle  of 
its  body,  I never  knew  the  patient  complain  of  pain,  provided 
the  limb  was  well  supported  by  the  assistants  and  provided  no 
jerk  was  given  by  the  operator  himself.  In  that  operation,  the 
pain  occasioned,  by  the  division  of  the  skin  and  of  the  nerves, 
overcomes  every  other  pain,  and  I have  always  seen  patients 
impressed  with  the  popular  prejudice,  and  expecting  anxiously 
the  division  of  the  bone,  feel  quite  free  from  pain,  as  soon  as  the 
saw  had  begun  to  work.  Nay,  several,  after  expressing,  by  their 
cries,  the  most  acute  pain,  taking  advantage  of  the  kind  of  ease 
which  follows  the  division  of  the  flesh,  raise  their  head  and  look 
on,  while  the  bone  is  being  sawed  through;  at  once  actors  and 
spectators  in  this  last  part  of  a painful  and  bloody  operation. 

Yet  the  medullary  membrane,  the  injury  of  which  is  attend- 
ed with  no  pain,  while  in  a healthy  state,  becomes  the  seat  of 
the  most  exquisite  sensibility  in  the  pains  in  the  bones  which 
mark  the  last  stages  of  the  venereal  disease;  in  the  kind  of  con- 
version into  flesh,  of  the  solid  bone,  known  by  the  name  of 
spina  ventosa,  as  will  be  mentioned,  in  speaking  of  the  uses  of 
the  marrow,  in  the  chapter  on  the  organs  of  motion  and  on. 
their  action. 


292 


CHAPTER  VI, 

ON  NUTRITION. 

evil.  All  the  functions  which  we  have  hitherto  made  the 
object  of  our  study;  digestion,  by  which  the  alimentary  substan- 
ces received  within  the  body  are  deprived  of  their  nutritive 
parts;  absorption,  which  convevs  that  recrementitious  extract 
into  the  mass  of  the  fluids;  the  circulation,  by  which  it  is  carried 
to  the  parts  wherein  it  is  to  undergo  different  changes;  diges- 
tion, circulation,  absorption,  respiration,  and  the  secretions,  are 
but  preliminary  acts,  preparatory  to  the  more  essential  function 
treated  of  in  this  chapter,  and  the  consideration  of  which  termi- 
nates the  history  of  the  phenomena  of  assimilation. 

Nutrition  may  be  considered  as  the  complement  of  the  func- 
tions of  assimilation.  The  aliment  altered  in  its  qualities  by  a 
series  of  decompositions,  animalized  and  rendered  similar  to  the 
substance  of  the  being  which  it  is  to  nourish,  is  applied  to  the  or- 
gans whose  waste  it  is  to  repiur;  and  this  identification  of  the 
nutritive  matter  to  our  organs,  which  take  it  up  and  appropriate 
it  to  themselves,  constitutes  nutrition.  Thus  there  is  accomplish- 
ed a real  conversion  of  the  aliment  into  our  own  substance. 

There  is  incessantly  going  on  a waste  of  the  integrant  parti- 
cles of  the  living  body,  which  a multiplicity  of  circumstances 
tend  to  carry  away  from  it;  several  of  its  organs  are  constantly 
engaged  in  separating  from  it  the  fluids  containing  the  recre- 
mentitious materials  of  its  substance  worn  by  the  combined 
action  of  the  air  and  of  caloric,  by  inward  friction  and  by  a 
pulsatory  motion  that  detaches  its  particles. 

Alike,  therefore,  to  the  vessel  of  the  Argonauts,  so  often  re- 
paired in  the  course  of  a long  and  perilous  navigation,  that  on 
her  return,  no  part  of  her  former  materials  remained;  an  animal 
is  incessantly  undergoing  decay,  and  if  examined  at  two  differ- 
ent periods  of  its  duration,  does  not  contain  one  of  the  same 
paolecules.  The  experiment  performed  with  madder,  which 


ON  NUTRITION. 


293 

dyes  red  the  bones  of  animals  among  whose  food  it  is  mixed, 
proves  most  unquestionably,  this  incessant  decomposition  of 
living  matter.  One  has  only  to  interrupt,  for  a sufficient  length 
of  time,  the  use  of  that  plant,  to  make  the  uniformly  red  colour 
assumed  by  the  bones,  completely  disappear.  Now,  if  the  hard- 
est and  most  solid  parts,  most  calculated  to  resist  decay,  are 
undergoing  a perpetual  routine  of  decomposition  and  of  regene- 
ration, there  can  be  no  doubt,  that  this  motion  must  be  far  more 
rapid  in  those  whose  power  of  cohesion  is  much  inferior;  for 
example,  in  the  fluids. 

Attempts  have  been  made  to  determine  the  period  at  which 
the  body  is  completely  renovated;  it  has  been  said,  that  an  inter- 
val of  seven  years  was  required  for  one  set  of  molecules  to  dis- 
appear and  be  replaced  by  others;  but  this  change  must  go  on 
more  rapidly  in  childh  'oci  and  in  youth.  It  must  be  slower  at  a 
mature  age,  and  must  require  a considerable  time,  at  a very  ad- 
vanced period  of  life,  when  all  the  parts  of  the  body  become, 
in  a remarkable  degree,  fixed  and  firm  in  their  consistence, 
while  the  vital  powers  become  more  languid.  There  can  be  no 
doubt,  that  the  sex,  the  habit,  the  climate  in  which  we  live,  the 
profession  we  follow,  our  mode  of  life,  and  a variety  of  other 
circumstances,  accelerate  or  retard  it;  so  that  it  is  absolutely 
impossible  to  fix,  with  any  degree  of  certainty,  its  absolute 
duration. 

CVIII.  The  parts  of  our  body,  in  proportion  as  they  under- 
go decay,  are  repaired  only  by  means  of  homogeneous  particles 
exactly  like  themselves:  were  it  otherwise,  their  nature,  which 
always  remains  the  same,  would  be  undergoing  perpetual 
changes. 

When,  in  consequence  of  the  successive  changes  which  it 
has  undergone  from  the  action  of  the  organs  of  digestion,  of 
absorption,  of  the  circulation,  of  respiration,  and  of  secretion, 
the  nutritive  matter  is  animalized  or  assimilated  to  the  body 
which  it  is  to  nourish,  the  parts  which  it  moistens  retain  it  and 
incorporate  it  to  their  own  substance.  This  nutritive  identifi- 
cation is  not  performed  alike  in  the  brain,  in  the  muscles,  in  the 
bones.  See.  Each  of  them  appropriates  to  itself,  by  a real  pro- 
cess of  secretion,  whatever  it  meets  with  fitted  for  its  nature, 
in  the  fluids  conveyed  to  it  by  the  different  kinds  of  vessels,  but 


ON  NUTRITION. 


294 

especially  by  the  arteries;  leaving  unaffected,  the  remaining 
heterogeneous  particles.  A bone  is  a secretory  organ,  around 
which  phosphate  of  lime  is  deposited;  the  lymphatic  vessels 
which,  in  the  process  of  nutrition,  perform  the  office  of  excre- 
tory ducts,  remove  that  saline  substance,  when  it  has  lain  suf- 
ficiently long  in  the  cells  of  its  tissue.  The  same  happens  to 
the  muscles,  with  regard  to  fibrina,and  to  albumen  with  regard 
to  the  brain:  every  part  appropriates  to  itself,  and  converts  into 
a solid  form,  those  fluids  which  are  of  the  same  nature,  in  vir- 
tue of  a power  of  which  the  term  affinity  of  aggregation,  used 
in  chemistry,  gives  an  idea,  and  of  which  it  is  perhaps  the  em- 
blem. 

The  nutrition  of  a part  requires  that  it  should  be  possessed 
of  sensibility  and  motion.  By  tying  the  arteries  and  nerves  of  a 
part,  it  cannot  be  nourished  nor  can  it  live.  The  blood  which 
flows  along  the  veins,  the  fluid  conveyed  by  the  absorbents, 
contain,  in  a smaller  proportion  than  arterial  blood,  vivifying 
and  reparatory  particles.  It  is  even  commonly  thought,  that 
the  lymph  and  venous  blood  contain  no  directly  nutritive  parti- 
cles. As  to  the  share  which  the  nerves  take  in  the  process  of 
nutrition,  that  is  not  yet  completely  determined.  A limb  that 
is  paralyzed,  by  the  division  or  tying  of  its  nerves,  or  by  any 
other  affection,  sometimes  retains  its  original  size  and  plump- 
ness; most  frequently,  however,  though  perhaps  for  want  of 
motion,  it  becomes  emaciated,  and  shrinks  in  a remarkable 
degree. 

CIX.  We  should  be  enabled  to  understand  the  process  of 
nutrition,  if  after  having  accurately  determined  the  difference 
of  composition  between  our  food,  and  the  substance  itself  of 
our  organs,  we  could  see  how  each  function  robs  the  aliments 
of  their  qualities,  to  assimilate  them  to  our  own  bodies;  and 
what  share  each  function  takes  in  the  transmutation  of  the  nu- 
tritive particles  into  our  own  substance.  To  illustrate  this  point, 
suppose  a man  to  live  exclusively  on  v'egetable  substances,  which 
in  fact,  form  the  basis  of  our  food;  on  whatever  part  of  the 
plant  he  may  live,  whether  on  the  stem,  on  the  leaves,  on  the 
blossoms,  on  the  seeds,  or  on  the  root;  carbon,  hydrogen,  and 
oxygen  enter  into  the  composition  of  these  vegetable  substan- 


ON  NUTRITION, 


295 


ces,  which,  by  a complete  analyis,  may  all  be  resolved  into 
water  and  carbonic  acid.  To  these  three  constituent  principles^ 
there  is  frequently  united  a small  quantity  of  azote,  of  salts,  and 
of  other  materials,  in  different  proportions.  If  then,  we  examine 
the  nature  of  the  organs  in  this  man,  whose  food  is  entirely 
vegetable,  it  will  be  found  that  they  are  different  in  their  com- 
position, a;)d  far  more  animalized  than  that  kind  of  food;  that 
azote  predominates,  though  the  vegetable  substance  contains 
none  or  only  a very  small  quantity;  that  new  products,  undis- 
tinguishable  in  the  aliments,  exist,  in  considerable  quantity,  in 
the  body  which  is  fed  on  them,  and  appear  produced  by  the 
very  act  of  nutrition. 

The  essence  of  this  function  is,  therefore,  to  make  the  nutritive 
matter  undergo  a more  advanced  state  of  composition,  to  de- 
prive it  of  a portion  of  its  carbon  and  of  its  hydrogen,  to  make 
azote  predominate,  and  to  produce  several  substances,  which 
did  not  exist  in  it  before.  All  living  bodies  seem  to  possess  the 
faculty  of  composing  and  decomposing  the  substances  by  means 
of  which  they  are  maintained,  and  to  form  new  products;  but 
they  possess  it  in  various  degrees  of  energy.  The  sea  weed, 
from  the  ashes  of  which  soda  is  obtained,  on  being  sown  in  a 
box  of  soil,  in  which  there  is  not  a single  particle  of  that  alkali, 
and  watered  with  distilled  water,  will  no  longer  contain  it,  as  if  it 
had  grown  on  the  sea  shore,  in  the  midst  of  marshes  constantly 
inundated  by  salt  and  brackish  water.* 

Living  bodies  then,  are  real  laboratories,  in  which  there  are 
carried  on  combinations  and  decompositions  which  art  cannot 

* I am  unacquainted  with  the  details  of  the  experiment  referred  to  by  the 
author;  he  quotes  it,  I conceive,  to  show  that  the  powe^r  which,  he  says,  is 
common  to  all  living  bodies,  of  producing  a substance  not  supplied  to  theiri 
from  without,  is  not  possessed,  in  the  same  degree,  by  all  bodies  endowed  with 
life;  since  the  sea  weed  here  alluded  to  does  not  possess  it,  in  an  equal  degree, 
when  watered  with  distilled  as  with  sea  water.  This,  I apprehend,  is  the  au- 
thor’s meaning,  though  the  text  is  somewhat  obscure,  and  would  almost  lead 
one  to  believe  he  meant,  that  no  alkali  whatever  can  be  obtained  from  the  sea 
plant  under  the  circumstances  he  states.  “ L’algue  marine  dont  les  cendres 
“ fournissent  la  soude,  semee  dans  une  caisse  pleine  d’un  terreau  qui  ne  conti- 
“ ent  pas  un  seul  atome  de  cet  alkali,  arrocee  avec  I’eau  distill^e,  ne  le fourvit 
“plus  comme  si  elle  avoit  pris  sa  croissance  au  milieu  des  marais  toujours  in,- 
“ cndes  par  leurs  eaux  saumatres  et  muriatiques.”  T. 


ON  NUTRITION. 


296 

imitate;  bodies  that  appear  to  us  simple,  as  soda  andsilex,  seem 
to  be  formed  by  the  union  of  their  constituent  particles;  while 
other  bodies,  whose  composition  we  do  not  understand,  under- 
go an  irresistible  decomposition;  hence,  methinks,  one  may  in- 
ter, that  the  power  of  nature  in  the  composition  and  decomposi- 
tion  of  bodies,  far  exceeds  that  of  chemistry. 

Straw  and  cereal  plants  contain  an  enormous  quantity  of  silex, 
even  when  the  earth  in  which  they  grow  has  been  carefully  de- 
prived of  its  siliceous  particles.  Oats,  particularly,  contain  a 
considerable  quantity  of  that  vitr: liable  earth;  the  ashes  obtained 
by  burning  its  seed,  on  being  analyzed  by  means  of  the  nitric 
acid,  were  found  by  M.  Vauquelin,  to  contain  y®oVo  of  pure  si- 
lex  indissoluble  in  that  acid,  and  0,393  of  phosphate  of  lime 
dissolved  in  it. 

The  excrements  of  a hen,  fed,  for  ten  days,  on  oats  only,  on 
being  calcined  and  analyzed  by  the  same  chemist,  produced 
twice  as  much  phosphate  and  carbonate  of  lime  as  was  contained 
in  the  oats,  with  a small  deficiency  in  the  quantity  of  silex, 
which  might  have  been  employed  in  furnishing  the  excess  of 
calcareous  matter;  a transmutation  depending  on  the  absorption 
ol  an  unknown  principle,  to  the  amount  of  nearly  five  times  its 
own  weight.* 

CX.  A substance  to  be  fit  for  our  nourishment,  should  be  ca- 
pable of  decomposition  and  fermentation;  or  in  other  words  ca- 
pable of  undergoing  an  inward  and  spontaneous  change,  so  that 
its  elements  and  relations  may  be  altered.  This  spontaneous 
susceptibility  of  decomposition,  excludes  from  the  class  of  ali- 
ments whatever  is  not  organized  and  is  not  a part  of  a living 
body;  thus,  mineral  substances  absolutely  resist  the  action  of 
our  organs  and  are  not  convertible  into  their  own  substance. 
The  common  principle  extracted  from  aliraentarj^  substances, 
however  varied  they  may  be,  the  aliment,  as  Hippocrates  terms 
it,  is,  most  probably,  a compound  highly  subject  to  decomposi- 
tion and  fermentation;  this  is  likewise  the  opinion  of  all  those 
who  have  endeavoured  to  determine  its  nature.  Lorry  thinks 
it  is  a mucous  substance;  Cullen  says  it  is  saccharine;  Professor 

* See  the  Annales  de  Chimie,  and  the  Systhne  des  Connaissances  chimiques  de 
Foui’croy,  tome  x.  pag'e  ?2. 


ON  NUTRITION. 


297 

Halle  considers  It  as  an  hydro-carbonous  oxide,  which  differs 
from  the  oxalic  acid,  only  in  containing  a smaller  quantity  of 
oxygen.  It  is  evident,  that  these  three  opinions  are  very  much 
alike,  since  oxygen,  carbon,  and  hydrogen,  combined  in  differ- 
ent proportions,  form  the  mucous  and  saccharine  substances 
and  the  base  of  the  oxalic  acid.  On  analyzing  the  animal  sub- 
stance, by  means  of  the  nitric  acid,  it  is  reduced  to  this  last 
base,  by  depriving  it  of  a considerable  quantity  of  azote  which 
constitutes  its  most  remarkable  character. 

But  whence  comes  this  enormous  quantity  of  azote?  How 
happens  it,  that  the  flesh  of  a man  living  exclusively  on  vege- 
tables, contains  as  much  azote  and  ammonia,  and  is  as  putres- 
cent, as  that  of  a man  living  on  animal  food?  Respiration  does 
not  introduce  a single  particle  of  azote  into  our  fluids;  this  gas 
comes  out  of  the  lungs  as  it  entered;  the  oxygen  alone  is  dimi- 
nished in  quantity.  Might  not  one  suspect  that  this  element  of 
animal  substances  is  a product  of  the  vital  action,  and  that  in- 
stead of  receiving  it  from  our  aliments,  we  form  it  within  our- 
selves, by  an  act  that  is  hyper-chemical;  that  is,  which  chemis- 
try cannot  imitate?'*' 

CXI.  It  has  been  maintained,  that  the  hydro-carbonous  oxide 
combines  in  the  stomach  and  intestinal  canal  with  oxygen, 
whether  this  last  principle  has  entered,  with  the  aliments,  into 
the  digestive  tube,  or  whether  it  is  furnished  by  the  decompo- 
sition of  the  fluids  within  that  cavity.  The  intestinal  fluids  extri- 
cate azote,  which  combines  with  the  alimentary  mass,  and  occu- 
pies the  place  of  the  carbon  which  the  oxygen  has  taken  from  it, 
to  form  carbonic  acid.  On  reaching  the  lungs,  and  being  again 
exposed  to  the  action  of  the  oxygen  of  the  atmosphere,  this  gas 
robs  it  of  a portion  of  its  carbon,  and  as  it  disengages  the  azote 
of  the  venous  blood,  it  brings  about  a new  combination  of  that 
principle  with  the  chyle:  lastly,  propelled  with  the  blood  to  the 
surface  of  the  skin,  the  atmospherical  oxygen  disengages  its 
carbon,  and  completes  its  azotisation.  The  cutaneous  organ  is 

* The  late  experiments  of  Messrs.  Allen  and  Pepys  prove  that  when  an 
animal  is  made  to  breathe  pure  oxygen,  the  blood  disengages  a certain  quan- 
tity of  azote  and  absorbs  an  equal  quantity  of  oxygen.  Philosophical  Transac- 
tions,  1809. 

2 P 


298 


ON  NUTRITION. 


perhaps  to  the  lymphatic  system,  what  the  pulmonary  organ  is 
to  the  sanguineous  system. 

The  animalization  of  the  animal  substance  is  therefore  effect- 
ed, principally  by  the  loss  of  its  carbon,  which  is  replaced  by  the 
excess  of  azote  in  the  animal  fluids.  These  maintain  them- 
selves, in  this  manner,  in  a due  temperament;  for  continually 
parting  with  the  carbonous  principle  in  the  intestinal,  pulmon- 
ary, and  cutaneous  combinations,  they  would  be  over  animal- 
ized,  if  an  additional  quantity  of  chyle  did  not  seize  the  azote, 
which  is  in  excess.  Still  this  theory  does  not  account  for  the 
formation  of  the  phosphoric  salts,  of  the  adipocere,  and  a variety 
of  other  products;  but  without  adopting  it,  to  the  full,  one  may 
presume,  from  the  experiments  and  facts  on  which  it  rests,  that 
the  oxygen  of  the  atmospherical  air  is  one  of  the  most  power- 
ful agents  employed  by  nature,  in  the  transformation  of  the 
aliments  we  live  upon,  into  our  substance. 

How  are  those  animals  nourished  which  live  solely  on  more 
animalized  flesh,  that  is  containing  a greater  quantity  of  azote, 
and  a greater  proportion  of  ammonia  than  their  own  substance. 
In  such  a case,  the  assimilation  of  the  aliments,  consists  in  their 
desanimalization  either  by  the  co-operation  of  all  the  organs, 
or  by  the  sole  action  of  the  digestive  organs,  by  the  combination 
of  the  gastric  juice  with  the  other  fluids. 

The  constituent  elements  entering  into  the  composition  of  our 
organs,  whether  coming  from  the  exterior,  or  formed  by  the 
vital  power  itself,  are  thrown  out  of  our  body  by  the  different 
emunctories,  and  cease  to  form  a part  of  it,  after  remaining 
within  it  for  a limited  time.  The  urine  carries  along  with  it 
an  enormous  quantity  of  azote;  the  lungs  and  the  liver  rid  us  of 
the  carbon  and  of  the  hydrogen;  the  oxygen  which  contains 
eighty-five  parts  in  the  hundred,  in  the  composition  of  water,  is 
evacuated  by  means  of  the  aqueous  secretions,  which  carry  off, 
in  a state  of  solution,  the  saline  and  other  soluble  principles. 

Among  those  salts  there  is  one,  but  little  soluble,  and  which, 
nevertheless,  is  of  primary  consequence  among  the  constitu- 
ent principles  of  the  animal  economy.  Phosphate  of  lime,  in 
fact,  forms  the  base  of  several  organs;  it,  almost  entirely,  forms 
the  osseous  system,  at  an  advanced  period  of  life;  all  the  white 


ON  NUTRITION. 


299 


organs;  all  our  fluids  contains  a remarkable  quantity  of  that  sub- 
stance, of  which  the  economy  rids  itself  by  a kind  of  dry  secre- 
tion. The  outer  covering  is,  in  all  animals,  the  emunctory 
destined  for  that  purpose;  the  annual  moulting  of  birds,  the  fall 
of  the  hair  of  quadrupeds,  the  renovation  of  the  scales  of  fishes 
and  reptiles,  carry  off  every  year,  a considerable  quantity  of 
calcareous  phosphate.  Man  is  subject  to  the  same  laws,  with 
this  difference,  that  the  annual  desquamation  of  the  epidermis, 
is  not  under  the  absolute  influence  of  the  seasons,  as  in  the 
brute  creation.  The  human  epidermis  is  renewed  annually,  as 
well  as  the  hair  on  the  head  and  on  the  body;  but  this  change 
is  brought  about  gradually,  and  is  not  completed  in  a season; 
it  does  not  take  place  in  the  spring,  as  in  most  animals,  nor  in 
autumn  with  the  fall  of  the  leaf,  though  at  these  two  periods, 
the  hair  falls  off  in  greatest  quantity,  and  the  desquamation  of 
the  cuticle  is  most  active.  These  two  phenomena  last  through- 
out the  whole  year,  as,  in  southern  climates,  the  fall  of  the  leaves 
and  the  renovation  of  vegetation  are  continually  going  on.  As 
will  be  mentioned,  in  speaking  of  the  functions  of  generation, 
man  living  in  a state  of  society,  and  enjoying  all  the  advantages 
of  civilization,  is  not  as  much  under  the  influence  of  the  seasons 
as  the  inferior  animals.  One  cannot,  however,  but  observe,  that 
the  successive  shedding  and  renewing  of  the  epidermoid  parts, 
as  the  cuticle,  the  nails,  and  the  hair,  are  among  the  most 
effective  means  which  nature  possesses  of  parting  with  the 
phosphate  of  lime,  so  abundant  in  all  animals,  and  which, 
nevertheless,  is  so  insoluble  and  consequently  so  unfit  to  be 
carried  out  of  the  system,  along  with  the  excrementitious  fluids. 
This  effect  is  very  remarkable,  on  the  termination  of  several 
diseases,  in  the  salutary  renovation  of  the  solids  and  fluids 
which  take  place  during  convalescence.  The  hair  ceases  to 
grow  on  the  bald  head  of  an  old  man;  his  perspiration  dimin- 
ishes: may  not  this  be  the  cause  of  the  great  quantity  of  calca- 
reous salts,  of  the  ossification  of  the  vessels,  of  the  induration 
of  the  membranes? 

CXII.  What  is  the  ultimate  result  presented  to  us,  by  this 
series  of  functions,  linked  together,  growing  out  of  one  another, 
and  all  acting  on  the  matter  of  nutrition,  from  the  moment  it  is 
received  within  the  body,  till  it  is  applied  to  the  growth  and 


300 


ON  NUTRITION. 


reparation  of  its  organs?  It  shows  us  man  living  within  himself, 
unremittingly  employed  in  converting,  into  his  own  substance, 
heterogeneous  substances,  and  reduced  to  an  existence  purely 
vegetative,  inferior  even  to  the  greater  part  of  organized  beings, 
in  his  powers  of  assimilation.  But  how  high  is  he  not  placed 
above  them  all,  in  the  exercise  of  those  functions  we  are  now 
about  to  contemplate;  functions,  which  raise  him  above  his  own 
nature,  which  enlarge  the  sphere  of  his  existence,  which  serve 
him  to  provide  for  all  his  wants,  and  to  keep  up,  with  all  nature, 
those  manifold  relations  which  subject  her  to  his  empire! 


FIRST  CLASS. 


SECOND  ORDER. 


Functions  which  tend  to  the  preservation  of  the  Individual, 
by  establishing  his  relations  with  the  beings 
that  surround  him. 


SOS 


CHAPTER  VII. 

OF  SENSATIONS. 

cxiii.  We  have  already  seen,  how  the  human  body,  es-s 
sentially  changeable  and  perishable,  maintains  itself  in  its  natural 
economy,  carries  on  its  growth,  and  supplies  its  decay,  by  assi= 
milating  to  its  own  substance,  principles  that  are  yielded  to  it  by 
*the  food  it  digests,  and  by  the  air  it  breathes.  We  shall  now  pro- 
ceed to  examine  by  what  organs  man  is  enabled  to  keep  up  with 
all  nature,  the  relations  on  which  his  existence  depends:  by  what 
means  he  is  made  aware  of  the  presence  of  objects  which  con- 
cern him,  what  means  he  possesses  to  fit  his  connexion  with 
them  to  his  welfare,  to  draw  them  towards  him  or  to  repel 
them,  to  approach  or  to  avoid  and  escape  them,  as  he  perceives 
in  them  danger,  or  the  promise  of  enjoyment. 

Man  possesses,  in  all  its  plenitude,  this  new  mode  of  existence, 
which  is  denied  to  vegetable  nature.  Of  all  animals  it  is  he  that 
receives  impressions  the  most  crowded  and  various,  that  is  most 
filled  with  sensations,  and  that  employs  them  with  the  most  pow- 
erful combination,  as  the  materials  of  thought,  and  the  sources 
of  intelligence:  he  is  the  best  organized  for  feeling  the  action  of 
all  beings  around  him,  and  re-acting  on  them  in  his  turn.  In  the 
study  which  we  are  about  to  undertake,  we  shall  see  many  in- 
struments placed  on  the  limits  of  existence,  on  the  surface  of 
the  living  being,  ready  to  receive  every  impression;  conductors, 
stretching  from  these  instruments  to  one  common  centre,  to 
which  all  is  carried:  conductors  through  which  this  central  or- 
gan regulates  the  actions  which  now  transport  the  whole  body 
from  one  place  to  another  {locomotion)-,  now  merely  change  the 
relative  situation  of  its  parts  {partial  motion)-,  and,  at  other 
times,  produce,  in  the  organs,  certain  dispositions,  of  which 
speech  and  language,  in  their  various  forms,  are  the  result. 

CXIV.  If  we  are  thoroughly  to  understand  the  mechanism 
of  this  action  of  outward  objects  on  our  body,  we  must  follow 
the  natural  succession  of  the  phenomena  of  sensation;  studying 
first  the  bodies  which  produce  the  sensitive  impression;  ex- 


OF  SENSATIONS. 


304 

amining  next  the  organs  that  receive  it;  and  next  the  conduc- 
tors which  transmit  it  to  a particular  centre,  whose  office  is  per- 
ception. To  take  the  sense  of  sight,  for  instance,  we  can  never 
understand  how  it  is  that  light  procures  us  the  knowledge  of 
certain  qualities  of  bodies,  if  we  have  not  learnt  the  laws  to 
which  that  fluid  is  subjected,  if  we  know  nothing  of  the  confor- 
mation of  the  eyes,  of  the  nerves  by  which  those  organs  commu- 
nicate with  the  brain-  and  of  the  brain  itself,  whither  all  sensa- 
tions, or  rather  the  motions  in  which  they  consist,  are  ultimately 
carried. 

CX  V.  Of  light.  At  this  day,  the  greater  part  of  natural  phi-* 
losophers  consider  it  as  a fluid  impalpable  from  its  exceeding 
tenuity.  Many  believe  it  to  be  only  a modification  of  caloric,  or 
of  the  matter  of  heal;  and  this  last  opinion  has  received  much 
plausibility  from  the  late  observations  of  Herschel.*  I shall  not 
examine  whether,  as  Descartes  and  his  followers  imagine,  light, 
consisting  of  globular  molecules,  exists  of  itself,  uniformly  dif- 
fused through  space;  or  as  Newton  has  taught  us  to  believe,  it 
be  but  an  emanation  of  the  sun  and  fixed  stars,  which  throw  off, 
from  their  whole  surface,  a part  of  their  substance,  without  ever 
exhausting  themselves  by  this  continual  efflux:  It  is  enough  for 
us  to  know,  1st,  that  the  rays  of  this  fluid  move  with  such  velo- 
city, that  light  passes,  in  a second,  through  a distance  of  seventv- 
two  thousand  leagues,  since,  according  to  the  calculation  of 
Roemer  and  the  tables  of  Cassini,  it  traverses  in  something  less 
than  eight  inmutes  the  thirty-three  millions  of  leagues  that  se- 
parate us  from  the  sun?  2dly,  that  light  is  called  direct  when  it 
passes  from  the  luminous  body  to  the  eye,  without  meeting  anv 
obstacle;  refected,  when  it  is  thrown  back  to  that  organ  by  an 
opake  body;  refracted,  when  its  direction  has  been  changed  by 

* This  celebrated  Astronomer  has  published,  in  the  Philosophical  Transac- 
tions of  the  Royal  Society  for  1800,  a series  of  experiments  which  show,  that 
the  different  coloured  rays,  heat,  in  different  degrees,  the  bodies  on  which 
they  fall,  and  that  the  red  ray,  which  is  the  least  refrangible,  gives  also  the 
greatest  heat. 

The  thermometer  placed  out  of  the  spectrum  and  towards  the  red  ray,  so 
that  it  would  receive  any  rays  yet  less  refrangible,  rises  higher  than  when  it 
is  placed  in  that  colour:  From  which  Herschel  concludes  that  rays  are  given 
out  by  the  sun,  too  little  refrangible  to  produce  the  sensation  of  light,  and  of 
colours,  but  which  produce  the  sensation  of  heat. 


OF  SENSATIONS. 


305 


passing  from  one  transparent  medium  to  another  of  different  den- 
sity: 3dly,  that  the  rays  of  light  are  reflected  at  an  angle  equal 
to  that  of  incidence;  that  a ray,  passing  through  a* transparent 
body,  is  more  strongly  refracted  as  the  body  is  more  convex  on 
the  surface,  denser,  or  of  more  combustible  elements.  It  was 
from  this  last  observation,  that  Newton  conjectured  the  com- 
bustibility of  the  diamond,  and  the  existence  of  a combustible 
principle  in  water,  since  placed  beyond  doubt,  by  the  beautiful 
experiments  of  modern  chemistry:  4thly,  that  a ray  of  light  re- 
fracted by  a glass  prism  is  decomposed  into  seven  rays,  red, 
orange,  yellow,  green,  blue,  indigo,  and  violet.  Each  of  these 
rays  is  less  refrangible,  as  it  is  nearer  to  the  red.  This  ray  is  of 
all,  that  which  strikes  the  eyes  with  the  greatest  force,  and  pro- 
duces on  the  retina  the  liveliest  impressions.  The  eagerness  of 
savages  for  stuffs  of  this  colour  is  well  known.  Among  almost 
all  nations  it  has  dyed  the  mantle  of  kings:  it  is  the  most  bril- 
liant and  splendid  of  all:  there  are  animals  whose  eyes  seem 
scarcely  to  sustain  it:  I have  seen  maniacs  whose  madness,  after 
a long  suspension,  never  failed  to  break  out  at  the  sight  of  a red 
cloth,  or  of  one  clothed  in  that  colour.  Green  is,  on  the  con- 
trary, the  softest  of  colours;  the  most  permanently  grateful;  that 
which  least  fatigues  the  eyes,  and  on  which  they  will  longest  and 
most  willingly  repose.  Accordingly,  nature  has  been  profuse 
of  green,  in  the  colouring  of  all  plants;  she  has  dyed,  in  some 
sort,  of  this  colour,  the  greater  part  of  the  surface  of  the  globe. 
When  the  eyes  bear  uneasily  the  glare  of  too  strong  a light, 
glasses  of  this  colour  are  used  to  soften  the  impression,  which 
slightly  tinge,  with  their  own  hue,  all  the  objects  seen  through 
them.  Lastly,  the  violet  ray,  last  in  the  scale,  of  which  the  mid- 
dle place  is  filled  by  the  green,  is  of  all  the  weakest,  the  most 
refrangible.  Of  all  colours,  violet  has  the  least  lustre;  forms 
show  to  less  advantage  under  it;  their  prominences  are  lost: 
painters  accordingly  make  but  little  use  of  it.  When  an  en- 
lightened body  reflects  all  the  rays,  the  sensations  they  might 
separately  produce  blend  into  the  sensation  of  white;  if  it  re- 
flect a few,  it  appears  differently  coloured,  according  to  the  rays 
it  repels:  finally,  if  all  be  absorbed,  the  sensation  of  black  is  pro- 
duced, which  is  merely  the  negation  of  all  colour.  A black  body 
is  wrapped  in  utter  darkness,  and  is  visible  only  by  the  lustre  of 

2Q 


OF  SENSATIONS, 


306 

those  that  surround  it:  5thly,  that  from  every  point  in  the  sur- 
face of  a luminous  or  enlightened  body,  there  issue  a multitude 
of  rays,  diverging  according  to  their  distance,  with  a propor- 
tionate diminution  of  their  effect;  so  that  the  rays  from  each 
visible  point  of  the  body,  form  a cone,  of  which  the  summit 
is  at  that  point,  and  the  base,  the  surface  of  the  eye  on  which 
they  fall. 

CXVI.  Sense  of  sight.  The  eyes,  the  seat  of  this  sense,  are 
so  placed  as  to  command  a great  extent  of  objects  at  once,  and 
enclosed  in  two  osseous  cavities,  known  by  the  name  of  orbits. 
The  base  of  these  cavities  is  forwards,  and  shaped  obliquely 
outwards;  so  that  their  outward  side  not  being  so  long  as  the 
others,  the  ball  of  the  eye  supported,  on  that  side,  only  by  soft 
parts,  may  be  directed  outwards  and  take  cognizance  of  objects 
placed  to  a side,  without  its  being  necessary,  at  the  same  time,  to 
turn  the  head.  In  proportion  as  we  descend  from  man  in  the 
scale  of  animated  beings,  the  shape  of  the  base  of  the  orbits  be- 
comes more  and  more  oblique;  the  eyes  cease  to  be  directed  for- 
ward; in  short,  the  external  side  of  the  socket  disappears,  and 
the  sight  is  entirely  directed  outward;  and  as  the  physiognomy 
derives  its  principal  character  from  the  eyes,  its  expression  is 
absolutely  changed.  In  certain  animals  very  fleet  in  running, 
such  as  the  hare,  the  lateral  situation  of  the  organs  of  vision 
prevents  the  animals  from  seeing  small  objects  placed  directly 
before  them;  hence  those  animals,  when  closely  pursued,  are  so 
easily  caught  in  the  snares  which  are  laid  for  them. 

The  organ  of  sight  consists  of  three  essentially  distinct  parts. 
The  one  set  intended  to  protect  the  eye-ball,  to  screen  it,  at 
times,  from  the  influence  of  light,  and  to  maintain  it  in  the  con- 
ditions necessary  to  the  exercise  of  its  functions;  these  parts  are 
the  eye-brows,  the  eye-lids,  and  the  lachrymal  apparatus,  and 
they  serve  as  appendages  of  the  organ.  The  eye-ball  itself  con- 
tains two  parts  answering  very  different  purposes;  the  one, 
formed  by  nearly  the  whole  globe,  is  a real  optical  instrument, 
placed  immediately  in  front  of  the  retina,  and  destined  to  pro- 
duce on  the  luminous  rays  those  changes  which  are  indispensa- 
ble in  the  mechanism  of  vision;  the  other,  formed  by  the  medul- 
lary expansion  of  the  optic  nerve,  is  the  immediate  organ  of  that 
function.  It  is  the  retina  which  alone  is  affected  by  the  impres- 


OF  SENSATIONS. 


307 

sion  of  light,  and  set  in  motion  by  the  contact  of  that  very  subtle 
fluid.  This  impression,  this  motion,  this  sensation,  is  transmit- 
ted to  the  cerebral  organ  by  the  optic  nerve,  the  expansion  of 
which  forms  the  retina. 

CXVII.  Of  the  Eye-brows^  the  eye-lids^  and  the  lachrymal 
apparatus  {Tutamina  oculi^  Haller).  The  more  or  less  dark 
colour  of  the  hairs  of  the  eye-brows,  renders  that  projection 
very  well  adapted  to  diminish  the  effect  of  too  livid  a light,  by 
absorbing  a part  of  its  rays.  The  eye-brows  answer  this  pur- 
pose the  more  completely,  from  being  more  projecting,  and 
from  the  darker  colour  of  the  hairs  which  cover  them;  hence 
we  depress  the  eye-brows,  by  knitting  them  transversely,  in 
passing  from  the  dark  into  a place  strongly  illuminated,  which 
causes  an  uneasy  sensation  to  the  organ  of  sight.  Hence,  like- 
wise, the  custom  that  prevails  with  some  southern  nations, 
whose  eye-brows  are  shaded  by  thicker  and  darker  hairs,  to 
blacken  them,  that  they  may  still  better  answer  the  purpose 
for  which  they  are  intended. 

The  eye-lids  are  two  moveable  curtains  placed  before  the 
eyes,  which  they  alternately  cover  and  uncover.  It  was  re- 
quisite that  they  should  be  on  the  stretch,  and  yet  capable  of 
free  motion;  now  both  these  ends  are  obtained  by  the  tarsal  car- 
tilages, which  are  situated  along  the  whole  of  their  free  edges, 
and  of  the  muscles  which  enter  into  their  structure.  The  cellu- 
lar tissue  which  unites  the  thin  and  delicate  skin  of  the  eye-lids 
to  the  muscular  fibres,  contains,  instead  of  a consistent  fat, 
which  would  have  impeded  its  motion,  a gelatinous  lymph, 
which,  when  in  excess,  constitutes  oedema  of  the  eye-lids.  The 
tissue  of  the  eye-lids  is  not  absolutely  opake,  since  even  when 
strongly  drawn  together,  and  completely  covering  the  globe  of 
the  eye,  one  may  still  discern  through  their  texture,  light  from, 
darkness.  On  that  account  light  may  be  considered  as  one  of 
the  causes  of  awakening,  and  it  is  of  consequence  to  keep  in  the 
dark,  patients  fatigued  by  want  of  sleep. 

The  principal  use  of  the  eye-lids,  is  to  shade  the  eyes  from 
the  continual  impression  of  light.  Like  all  the  other  organs,  the 
eyes  require  to  recruit  themselves  by  repose;  and  they  had  not 
been  able  to  enjoy  it,  if  the  incessant  impression  of  the  lumi- 
nous rays  had  continually  excited  their  sensibility.  The  remo- 


308 


OF  SENSATIONS. 


val  of  the  eye-lids  is  attended  with  loss  of.sleep.  The  fluids  are 
determined  to  the  affected  organ,  which  suffers  from  incessant 
irritation.  The  eyes  inflame,  the  inflammation  spreads  towards 
the  brain,  and  the  patient  expires  in  the  most  dreadful  agony. 
Thanks  to  an  advanced  state  of  civilization,  these  barbarous  tor- 
tures have  long  been  abolished;  but  what  happens,  when  from 
ectropium  of  one  or  other  of  the  eye-lids  a small  portion  of 
the  sclerotic  coat  or  cornea  remains  uncovered,  proves  the 
indispensable  necessity  of  those  parts.  The  spot  exposed  to  the 
continued  action  of  the  air  and  of  the  light,  becomes  irritated 
and  inflamed,  and  there  comes  on  an  ophthalmia,  which  can  be 
cured  only  by  bringing  together,  by  means  of  a surgical  opera- 
tion, the  divided  edges  of  the  opening  which  is  the  cause  of  the 
affection.  From  the  moveable  edges  of  both  eyelids  there  arise 
short  curved  hairs,  of  the  same  colour  as  those  of  the  eye-brow; 
they  are  called  eye-lashes,  and  are  intended  to  prevent  insects 
or  other  very  light  substances,  floating  in  the  atmosphere,  from 
getting  between  the  eye-ball  and  the  eye-lids. 

The  anterior  part  of  the  eye  thus  defended  against  external 
injuries,  is  continually  moistened  by  the  tears.  The  organ  which 
secretes  this  fluid,  is  a small  gland  situated  in  a depression  at  the 
anterior  and  external  part  of  the  arch  of  the  orbit,  imbedded  in 
fat,  and  supplied  with  pretty  considerable  vessels  and  nerves  in 
proportion  to  its  bulk,  and  pouring  the  fluid  it  secretes,  by 
means  of  seven  or  eight  ducts,  which  open  on  the  internal  sur- 
face of  the  upper  eye-lid,  by  capillary  orifices  directed  down- 
ward and  inward.  The  tears  arc  a muco-serous  fluid,  rather 
heavier  than  distilled  water,  saltish,  changing  to  a green  colour 
vegetable  blues;  and  containing  soda,  muriate  and  carbonate  of 
soda,  and  a very  small  quantity  of  phosphate  of  soda  and  of 
lime. 

In  ophthalmia,  the  irritation  of  the  conjunctiva,  transmitted 
by  sympathy  to  the  lachrymal  gland,  not  only  augments  the 
quantity  of  its  secretion,  but  appears,  likewise,  to  alter  the  quali- 
ties of  the  fluid  that  is  secreted.  The  tears,  which  in  those  cases 
flow  in  such  profusion,  bring  on  a sense  of  burning  heat  in  the 
inflamed  part;  do  they  not,  perhaps,  contain  a greater  quantity 
of  the  fixed  alkali  than  in  the  ordinary  state  of  the  parts;  and 
may  not  the  painful  sensation  depend  as  much  on  the  increased 


OF  SENSATIONS.  309 

proportion  of  soda  in  the  tears,  as  on  the  greater  sensibility  of 
the  conjunctiva? 

This  last  membrane  is  merely  a fold  of  the  skin,  which  is  ex- 
ceedingly thin,  covers  the  posterior  surface  of  the  eye-lids,  and 
is  then  reflected  over  the  anterior  part  of  the  eye  which  it  thus 
unites  to  the  eyelids.  From  the  whole  extent  of  its  surface, 
there  oozes  an  albuminous  serosity,  which  mingles  with  the 
tears,  and  adds  to  their  quantity.* 

The  tears  are  equably  diffused  over  the  globe  of  the  eye  by 
the  alternate  motions  of  the  palpebrse;  they  prevent  the  effects 
of  friction,  and  save  the  organ  of  sight  from  being  dried  at  that 
part  which  is  exposed  to  the  air.  The  air  dissolves,  and  carries 
off  in  evaporation  a part  of  the  lachrymal  fluid.  This  evapora- 
tion of  the  tears  is  proved  by  the  weeping  to  which  those,  in 
whom  that  secretion  is  very  profuse,  are  subject,  whenever  the 
atmospherical  air  from  being  damp  does  not  carry  off  a sufficient 
quantity  of  the  fluid.  The  unctuous  and  oily  fluid,  secreted  by  the 
meibomian  glands,  smears  the  loose  edge  of  the  palpebrae,  pre- 
vents the  tears  from  falling  on  the  cheek,  and  answers  the  same 
purpose  as  the  greasy  substance  with  which  one  anoints  the 
edges  of  a vessel,  filled  above  its  level,  to  prevent  the  overflow- 
ing of  the  contained  fluid. 

The  greatest  part  of  the  tears,  however,  flow  from  without 
inward,  and  towards  the  inner  canthus  of  the  eye;  they  take  that 
direction  in  consequence  of  the  natural  slope  of  the  moveable 
edge  of  the  palpebrse,  of  the  triangular  groove,  which  is  formed 
behind  the  line  of  union  of  their  edges,  whose  round  and  convex 
surfaces  touch  each  other  only  in  a point;  and  this  course  of  the 
tears  is,  likewise,  promoted  by  the  action  of  the  palpebral  por- 
tions of  the  orbicularis  palpebrarum,  whose  fibres,  having  their 
fixed  point  at  the  inner  angle  of  the  orbit  where  the  tendon  is 
inserted,  always  draw  in  their  external  commissure. 

* There  is  no  opening  in  the  part  which  corresponds  to  the  globe  of  the  eye; 
it  is  exceedingly  thin,  and  is  continued  under  the  name  of  conjunctiva  over  the 
transparent  cornea,  to  which  it  adheres  so  firmly  that  it  is  not  easily  separated 
from  it  In  some  animals  that  have  no  palpebrse,  the  skin  is  continued  of  the 
same  thickness  over  the  fore  part  of  the  eye.  The  conjunctiva  (if,  however, 
this  portion  of  skin  deserves  that  name)  when  opake,  renders  the  globe  of 
the  eye,  in  other  respects  imperfect,  absolutely  useless.  This  is  observed  in 
the  kind  of  eel,  called  in  books  of  natural  history,  murena  cnecilia:  the  gastro- 
branchus  cxcue  is  blind  from  the  same  circumstance^. 


OF  SENSATIONS. 


310 

On  reaching  the  internal  angle  of  the  palpebrae,  the  tears  accu- 
mulate in  the  lacus  lachrymalis,  a small  space  formed  between 
the  edges  of  the  palpebrse,  kept  separated  from  each  other  by 
the  caruncula  lachrymalis.  This  last  substance,  long  considered 
by  the  ancients  as  the  secretory  organ  of  the  tears,  is  merely  a 
collection  of  mucous  cryptse,  covered  over  by  a loose  fold  of  the 
conjunctiva.  These  follicles,  alike  in  nature  to  the  meibomian 
glands,  secrete  like  them  an  unctuous  substance,  which  smears 
the  moveable  edges  of  the  palpebrae  near  the  internal  commis- 
sure. The  edges  of  the  eye-lids  in  this  situation  required  a 
thicker  coating,  as  the  tears  accumulated  in  that  spot  have  no 
where  a greater  tendency  to  flow  on  the  cheek. 

Near  the  union  of  the  inner  sixth  of  the  free  edge  of  the  pal- 
pebrae with  the  remaining  five  sixths,  at  the  outer  part,  where  their 
internal,  straight,  or  horizontal  portion  unites  with  the  curved 
part,  there  are  situated  two  small  tubercles,  at  the  top  of  each 
of  which  there  is  a minute  orifice.  These  are  the  puncta  lachry- 
malia,  and  they  are  called  superior  and  inferior,  according  to 
the  palpebrae  to  which  they  belong.  In  the  dead  body  the  puncta 
do  not  appear  tubercular;  the  small  bulgings  produced,  doubt- 
less, by  a state  of  orgasm  and  of  vital  erection,  collapse  at  the 
approach  of  death.  These  small  apertures,  directed  inward  and 
backward,  are  incessantly  immersed  in  the  accumulated  tears, 
absorb  them,  and  convey  them  into  the  lachrymal  sac  by  means 
of  the  lachrymal  ducts,  of  which  they  are  the  external  orifices. 
The  absorption  of  the  tears,  and  their  flow  into  a membranous 
reservoir  lodged  in  the  groove  formed  by  the  os  unguis,  do  not 
depend  on  the  capillary  attraction  of  the  lachrymal  ducts;  each 
of  them,  endowed  with  a peculiar  vital  action,  takes  up  by  a 
real  process  of  suction,  the  tears  accumulated  in  the  lacus  lachry- 
malis^  and  determines  their  flow  into  the  sac.  The  weight  of  the 
fluid,  the  effort  of  the  columns  which  succeed  each  other,  co- 
operate with  the  action  of  the  parietes  of  the  duct.  The  flow  of 
the  tears  is  further  facilitated  by  the  compression  and  slight 
concussions  attending  the  contractions  of  the  palpebral  fibres  of 
the  orbicularis,  behind  which  the  lachrymal  ducts  are  situated. 
This  vitality  of  the  puncta  lachrymalia  and  of  the  ducts  is  rea- 
dily discovered  when  we  attempt  to  introduce  into  them  Anel’s 
syringe  or  Mej can’s  stylet,  to  remove  slight  obstructions  of  the 


OF  SENSATIONS. 


311 

lachrymal  passages.  In  a child  now  under  my  care  for  a mu- 
cous obstruction  of  the  nasal  duct,  I can  see  the  puncta  lachry- 
malia  contract,  when  the  extremity  of  the  syphon  does  not  at 
once  enter  the  canal.  One  is  then  obliged  to  wait  before  it  can 
be  introduced  for  a cessation  of  the  spasmodic  contraction, 
which  lasts  but  a few  moments.  The  tears  which  flow  into  the 
lachrymal  sac,  by  the  common  orifice  of  the  united  puncta 
lachrymalia,  never  accumulate  within  it,  except  in  case  of  mot- 
bid  obstruction;  they,  in  that  case,  at  once  enter  into  the  nasal 
duct,  which  is  a continuation  of  it,  and  fall  into  the  nasal  fossae, 
below  the  anterior  part  of  the  inferior  turbinated  bones  of  these 
cavities.  There  they  unite  with  the  mucus  of  the  nose,  increase 
its  quantity,  render  it  more  fluid,  and  change  its  composition. 
The  use  of  the  tears  is  to  protect  the  eye-ball  against  the  irri- 
tating impression  of  the  immediate  contact  of  the  atmosphere. 
They,  at  the  same  time,  favour  the  sliding  of  the  palpebrae, 
lessen  the  friction  in  those  parts  and  in  the  eye-ball,  and  thus 
promote  their  motion. 

CXVIII.  Of  the  globe  of  the  eya.  The  eye-ball,  as  was  al- 
ready observed,  may  be  considered  as  a dioptrical  instrument 
placed  before  the  retina;  whose  office  it  is  to  refract  the  lumi- 
nous rays,  and  to  collect  them  into  one  fasciculus,  that  may 
strike  a single  point  of  the  nervous  membrane  exclusively  cal- 
culated to  feel  its  impression.  An  outer,  membranous,  hard, 
and  consistent  covering  supports  all  its  parts.  Within  the  first 
membrane  called  the  sclerotic,  lies  the  choroid,  a darkish  coat, 
which  lines  the  inside  of  the  sclerotic,  and  forms  the  eye  into  a 
real  camera  obscura.  At  the  interior  part  of  the  globe,  there  is 
a circular  opening  in  the  sclerotic  in  which  the  transparent  cor- 
nea is  inserted.  At  about  the  distance  of  the  twelfth  part  of  an 
inch  from  this  convex  segment,  received  in  the  anterior  aper- 
ture of  the  sclerotica,  lies  the  iris,  a membranous  partition 
placed  perpendicularly,  and  containing  a round  opening  (the 
pupil),  which  dilates  or  contracts,  according  to  the  state  of  dila- 
tation or  contraction  of  the  iris. 

' At  the  distance  of  about  half  a line  from  the  back  part  of  the 
iris,  towards  the  union  of  the  anterior  fourth  of  the  globe  of  the 
eye  with  the  posterior  three  fourths,  opposite  to  the  opening  of 
the  pupil,  there  is  situated  a lenticular  body,  inclosed  in  a mem- 


312 


OP  SENSATIONS. 


branous  capsule,  immoveably  fixed  in  its  situation  by  adhering 
to  the  capsule  of  the  vitreous  humour. 

Behind  the  crystalline  lens,  the  posterior  three-fourths  of  the 
cavity  of  the  eye  contain  a viscid  transparent  humour,  enclosed 
in  the  cells  of  a remarkably  fine  capsule,  called  hyaloid.  This 
vitreous  humour  forms  about  two  thirds  of  a sphere  from  which 
the  anterior  segment  had  been  taken  out;  the  pulpous  expan- 
sion of  the  optic  nerve,  the  retina,  is  spread  out  on  its  surface, 
so  as  to  be  concentrical  to  the  choroid  and  sclerotic  coats. 

The  eye-ball  being  nearly  spherical,  the  length  of  its  different 
diameters  differs  but  little.  The  diameter  of  the  eye,  from  the 
fore  to  the  back  part,  is  between  ten  and  eleven  lines;  the  trans- 
verse and  vertical  diameters  are  somewhat  shorter.  Within  the 
space  measured  by  the  diameter  from  the  fore  to  the  back  part, 
there  are  situated,  taking  them  in  their  order  from  the  fore 
part,  the  cornea,  the  aqueous  humour  contained  in  the  anterior 
chamber,  the  iris  and  its  central  opening  or  pupil;  the  aqueous 
humour  of  the  posterior  chamber,  the  crystalline  lens,  surround- 
ed by  the  ciliary  processes;  then  the  vitreous  humour  in  its 
capsule;  and  behind  those  transparent  parts  of  the  eye,  through 
which  the  luminous  rays  pass  in  approaching  to  a perpendicu- 
lar, are  the  retina  which  receive  the  impression,  the  choroid 
whose  black  paint  absorbs  the  rays  that  pass  through  the  thin 
and  transparent  retina,  and  the  sclerotic  in  which  there  is  an 
opening  for  the  passage  of  the  optic  nerve  to  the  globe  if  the 
eye. 

The  cornea,  contained  in  the  anterior  aperture  of  the  sclerotica, 
like  the  glass  of  a watch  case  within  its  frame,  is  about  the  third 
of  a line  in  thickness;  it  forms,  at  the  fore  part  of  the  eye,  the 
segment  of  a smaller  sphere:  behind  it  lies  the  aqueous  humour 
which  fills  what  are  called  the  chambers  of  the  eye;  these  form 
spaces  divided  into  anterior  and  posterior;  the  former,  which  is 
the  larger  of  the  two,  bounded  by  the  cornea  at  the  fore  part, 
and  by  the  iris  at  the  back  part;  the  latter,  which  is  smaller 
and  separates  the  crystalline  humour  from  the  iris,  the  posterior 
part  of  which,  covered  by  a black  pigment,  is  called  the  uvea.* 

* Some  anatomists  have  doubted  the  existence  of  the  posterior  chamber  of 
the  eye;  but  to  be  convinced  of  its  existence,  one  need  but  freeze  an  eye, 
when  there  will  be  found  a piece  of  ice,  between  the  crystalline  lens  and  the 


OF  SENSATIONS. 


313 


The  specific  gravity  of  the  aqueous  humour  does  not  much  ex- 
ceed that  of  distilled  water;  some  have  even  thought  it  less;  it 
is  albuminous,  and  holds  in  solution  several  saline  substan- 
ces. The  crystalline,  inclosed  in  its  membranous  and  transpa- 
rent capsule,  is  a lenticular  body  rather  solid  than  fluid;  its 
consistence  is  particularly  great  towards  its  centre;  it  there 
forms  a kind  of  nucleus,  on  which  are  laid  several  concentric 
layers  whose  density  diminishes  as  they  approach  the  surface, 
where  the  external  layers,  truly  fluid,  form  what  Morgagni 
considered  as  a peculiar  liquid,  on  which  the  lens  might  be 
nourished  by  a kind  of  imbibition.  This  body,  composed  of 
two  segments  of  unequal  convexity,  about  two  lines  in  thick- 
ness at  its  centre,  consists  of  an  albuminous  substance  coagula- 
ble  by  heat  and  alkohol.  Extremely  minute  arteries  given  off 
by  the  central  artery  of  Zinn,  pass  through  the  vitreous  humour, 
and  bring  to  it  the  materials  of  its  growth  and  reparation. 

The  vitreous  humour,  so  called  from  its  resemblance  to  melted 
glass,  is  less  dense  than  the  crystalline  and  more  so  than  the 
aqueous,  and  is  in  considerable  quantity  in  the  human  eye;  it  ap- 
pears to  be  secreted  by  the  minute  arteries  which  are  distributed 
to  the  parietes  of  the  membrane  of  the  vitreous  humour;  it  is 
heavier  than  common  water,  somewhat  albuminous  and  saltish. 

The  sclerotica  is  a fibrous  membrane  to  which  the  tendons 
which  move  the  globe  of  the  eye  are  attached;  it  supports  all 
the  parts  of  that  organ,  and  these  collapse  and  decay,  whenever 

uvea.  The  formation  of  this  isicle  is  not  owing"  to  the  admission,  throug’h  the 
opening"  of  the  pupil,  of  the  aqueous  humour,  which,  like  all  other  fluids,  ex- 
pands considerably  on  freezing;  for  the  expansion  of  fluids  on  their  freezing 
being  proportioned  to  their  bulk,  the  vitreous  humour  which  freezes  at  the 
same  time  as  the  aqueous,  must  prevent  its  retrograde  flow  through  the  pupil. 
Lastly,  the  uvea  or  posterior  part  of  the  iris  is  covered  with  a black  point  which 
is  easily  detached  from  it;  now,  if  the  anterior  part  of  the  crystalline  lens  had 
been  in  immediate  contact  with  it,  it  would  have  been  soiled  by  some  of  this 
colouring  matter,  which  would  have  tarnished  its  natural  transparency,  indis- 
pensable to  perfect  vision.  It  is,  therefore,  undeniable  that  there  does  exist  a 
posterior  chamber,  which  is  to  the  anterior  in  the  proportion  of  two  to  five, 
and  containing  about  two  fifths  of  the  aqueous  humour,  the  whole  of  which  is 
estimated  at  five  grains,  and  that  the  iris  foi’ms  a loose  partition  between  the 
two  portions  of  the  aqueous  humour  in  which  the  dark  pigment  of  the  uvea 
is  insoluble.  The  aqueous  humour  appears  to  be  the  product  of  arterial  exha- 
lation, it  is  soon  reproduced,  as  we  see  after  the  operation  for  cataract. 

2 R 


314 


OF  SENSATIONS. 


the  continuity  of  its  external  covering  is  destroyed.  The  use  of 
the  choroid,  is  not  so  much  to  afford  a covering  to  the  other  parts, 
as  to  present  a dark  surface,  destined  to  absorb  the  luminous 
rays,  when  they  have  produced  on  the  retina  a sufficient  im- 
pression. If  it  were  not  for  the  choroid,  the  light  would  be  re- 
flected, and  after  having  impinged  on  the  nervous  membrane,  its 
rays  would  cross,  and  produce  only  indistinct  sensations.  Ma- 
riotte  thought  that  the  choroid  was  the  immediate  seat  of  vision, 
and  that  the  retina  was  only  its  epidermis.  This  hypothesis 
would  never  have  obtained  so  much  celebrity,  if,  besides  the 
objections  that  analogy  might  have  furnished  against  it,  there 
had  been  adduced,  in  opposition  to  it,  the  fact  observed  in 
fishes,  in  which  the  choroid  is  separated  from  the  retina,  by  a 
glandular  body,  opake  and  incapable  of  transmitting  the  lumi- 
nous rays.  The  retina  loses  its  form,  as  soon  as  it  is  separated 
from  the  vitreous  humour,  or  from  the  choroid  coat,  between 
which  it  is  spread  out  as  a very  thin  capsule,  so  soft  as  to  be 
almost  fluid.  A number  of  blood-vessels,  from  the  central  ar- 
tery of  Zinn,  are  distributed  on  the  nervous  substance  of  the 
retina,  and  give  it  a slight  pink  colour.  Ought  we,  with  Boer- 
haave,  to  attribute  to  aneurismal  or  varicose  enlargements  of 
those  small  vessels,  the  spots  which  are  seen  in  objects,  in  the 
disease  to  which  Maitre  Jean  gave  the  name  of  imaginationsf 
In  order  to  form  the  retina,  the  optic  nerve  enters  into  the 
globe  of  the  eye,  by  piercing  the  sclerotica,  to  which  the  cover- 
ing given  to  that  nerve  by  the  dura  mater  is  connected;  next 
penetrating  through  a very  thin  membrane  perforated  by  a num- 
ber of  small  holes  and  closing  the  opening  left  by  the  nerve, 
and  which  belongs  as  much  to  the  choroid  as  to  the  sclerotic 
coats,  it  spreads  out  to  furnish  the  expansion  which  lines  the 
concavity  of  the  choroid  and  covers  over  the  convex  surface 
of  the  vitreous  humour.  The  whole  extent  of  the  retina,  which 
is  equally  nervous  and  sentient,  may  receive  the  impression 
of  the  luminous  rays,  though  this  faculty  has„  by  several  philo- 
sophers, been  exclusively  assigned  to  its  central  part,  called 
the  optical  axis  or  porus  opticus.  This  central  part  is  easily 
recognized,  in  man,  by  a yellow  spot  discovered  by  Soem- 
mering; in  the  middle  of  this  spot,  situated  at  the  outer  side 
of  the  entrance  of  the  optic  nerve  into  the  globe  of  the  eye, 


OF  SENSATIONS. 


315 


there  is  seen  a dark  spot  and  a light  depression,  the  use  of 
which  is  not  understood.  This  peculiar  structure,  recently  dis- 
covered, is  met  with  only  in  the  eye  of  man  and  of  monkeys. 

CXIX.  Mechanism  and  phenomena  of  vision.  The  rays  of 
light  passing  from  any  point  of  an  enlightened  object,  form  a 
cone  of  which  the  apex  answers  to  the  point  of  the  object,  and 
of  which  the  base  covers  the  anterior  part  of  the  cornea.  All 
the  rays,  more  diverging,  which  fall  without  the  area  of  the 
cornea  on  the  eye-brows,  the  eye-lids  and  the  sclerotica,  are  lost 
to  vision.  Those  which  strike  the  mirror  of  the  eye  pass 
through  it,  under  a refraction  proportioned  to  the  density  of 
the  cornea,  which  much  exceeds  that  of  the  atmosphere,  and  to 
the  convexity  of  that  membrane:  approaching  the  perpendicular, 
they  now  pass  through  the  aqueous  humour,  less  dense,  and  fall 
upon  the  membrane  called  the  iris.  All  those  that  fall  upon  this 
membrane  are  reflected,  and  show  its  colour,  different  in  differ- 
ent persons,  and  apparently  depending  on  the  organic  texture, 
and  on  the  particular  and  very  diversified  arrangement  of  the 
nerves,  and  of  the  vessels,  and  cellular  tissue,  which  enter  into 
its  structure.  None  but  the  most  central  traverse  the  pupil  and 
serve  to  sight.  These  will  pass  that  opening,  in  greater  or  less 
number,  as  it  is  more  or  less  dilated.  Now,  the  pupil  is  enlarg- 
ed or  diminished,  by  the  contraction  or  expansion  of  the  iris. 

The  motions  of  this  membrane  depend  entirely  on  the  man- 
ner in  which  light  affects  the  retina.  The  iris  itself  is  insensible 
to  the  impression  of  the  rays  of  light,  as  Fontana  has  proved, 
who  always  found  it  immoveable,  when  he  directed  on  it  alone 
the  luminous  rays.  When  the  retina  is  disagreeably  affected, 
by  the  lustre  of  too  strong  a light,  the  pupil  contracts,  to  give 
passage  only  to  a small  number  of  rays:  it  dilates,  on  the  con- 
trary, in  gloom,  to  admit  enough  to  make  the  requisite  impres- 
sion on  the  retina. 

To  explain  the  motions  of  the  iris,  it  is  not  necessary  to  admit 
that  muscular  fibres  enter  into  its  structure;  it  is  enough  to  know 
its  vascular,  spungy  and  nervous  texture;  the  irritation  of  the 
retina  sympathetically  transmitted  to  the  iris,  determines  a more 
copious  afflux  of  humours;  its  tissue  dilates  and  stretches,  the 
circumference  of  the  pupil  is  pushed  towards  the  axis  of  this 
opening,  which  becomes  contracted  by  this  vital  expansion  of 


316 


OF  SENSATIONS. 


the  membranous  tissue.  When  the  irritating  cause  ceases  to 
act,  by  our  passing  from  light  into  darkness,  the  humours  flow 
back  into  the  neighbouring  vessels,  the  membrane  of  the  iris 
returns  upon  itself,  and  the  pupil  enlarges,  the  more  as  the 
darkness  is  greater*. 

The  rays,  admitted  by  the  pupil,  pass  through  the  aqueous 
humour  of  the  posterior  chamber,  and  soon  meet  the  crystalline, 
which  powerfully  refracts  them,  both  from  its  density,  and  its 
lenticular  form.  Brought  towards  the  perpendicular  by  this 
body,  they  pass  on  towards  the  retina  through  the  vitreous 
humour,  less  dense,  and  which  preserves,  without  increasing 
it,  the  refraction  produced  by  the  crystalline  lens.  The  rays, 
gathered  into  one,  strike  on  a single  point  of  the  retina,  and 
produce  the  impression  which  gives  us  the  idea  of  certain  pro- 
perties of  the  body  which  reflects  them.  As  the  retina  embraces 
the  vitreous  humour,  it  presents  a very  extended  surface  to  the 
contact  of  the  rays,  which  enables  us  to  behold,  at  once,  a great 
diversity  of  objects,  variously  situated  towards  us,  even  when 
we  or  these  objects  change  our  relative  situation.  The  luminous 
rays,  refracted  by  the  transparent  parts  of  the  eye,  form  there- 
fore, in  the  interior  of  the  organ,  a cone,  of  which  the  base 
covers  the  cornea,  and  applies  to  that  of  the  external  luminous 
cone,  whilst  its  apex  is  on  some  point  of  the  retina.  It  is  con- 
ceived, generally,  that  the  luminous  cones  issuing  from  all 
points  of  the  object  beheld,  cross  in  their  passage  through  the 
eye,  so  that  the  object  is  imaged  on  the  retina  reversed.  Admit- 
ting this  opinion,  established  on  a physical  experiment,  we  hare 
to  inquire,  why  we  see  objects  upright,  whilst  their  image  is 
reversed  on  the  retina.  The  best  explanation  we  possess  of  this 
phenomenon,  we  owe  to  the  English  philosopher  Berkeley,  who 
proposed  it  in  his  work,  entitled  Theory  of  Viaioriy  &c.  In  his 
opinion,  there  is  no  need  of  the  touch  to  correct  this  error  into 
which  sight  ought  to  betray  us.  As  we  refer  all  our  sensations 
to  ourselves,  the  uprightness  of  the  object  is  only  relative,  and 
its  inversion  really  exists  at  the  bottom  of  the  eye. 

By  the  point  of  distinct  vision,  is  understood  the  distance 
at  which  we  can  read  a book  of  which  the  characters  are  of  mid- 


Habitual  dilatation  of  the  pupil  is  a symptom  of  weakness,  of  WQiins,.  &c. 


OF  SENSATIONS. 


317 

dling  size,  or  distinguish  any  other  object  equally  small.  This 
distance  is  not  confined  within  very  narrow  limits,  since  we  can 
read  the  same  book  at  six  inches  from  the  eye,  or  at  five  or  six 
times  the  distance.  This  faculty  of  the  eyes  to  adapt  themselves 
to  the  distance  and  the  smallness  of  objects,  cannot  depend,  as 
has  been  fondly  repeated,  on  the  lengthening  or  shortening  of  the 
globe  of  the  eye  by  the  muscles  that  move  it.  Its  four  recti 
muscles  are  not,  in  any  case,  capable  of  compressing  it  on  its 
sides,  nor  of  lengthening  it  by  altering  its  spherical  form;  their 
simultaneous  action  can  only  sink  the  ball  in  its  socket,  flatten 
it  from  the  fore  to  the  back  part,  diminish  its  depth,  and  make 
the  refraction,  consequently,  less  powerful  when  objects  are 
very  distant  or  very  small:  this  last  effect,  even,  might  be  dis- 
puted. The  eye,  which  moves  and  rests  on  the  adipose  cushion 
which  fills  the  bottom  of  the  socket,  is  never  strongly  enough 
pressed  to  lose  its  spherical  figure,  which  of  all  the  forms  in  which 
bodies  can  be  invested,  is  that  which,  by  its  especial  nature, 
best  resists  alteration.  The  extremities  of  the  ciliary  processes, 
which  surround  the  circumference  of  the  crystalline  lens,  can- 
not act  on  this  transparent  lens,  compress  nor  move  it:  for  these 
little  membranous  folds,  of  which  the  aggregate  composes  the 
irradiated  disk,  known  under  the  name  of  corpus  ciliare,  possess- 
ing no  sort  of  contractile  power,  are  incapable  of  moving  the 
crystalline  lens,  with  which  their  extremities  lying  in  simple 
contiguity  have  no  adherence,  and  which,  besides,  is  immove- 
ably  fixed  in  the  depression  which  it  occupies,  by  the  adhesions 
of  its  capsule  with  the  membrane  of  the  vitreous  humour.  The 
various  degrees  of  contraction  or  dilatation  of  which  the  eye- 
ball is  susceptible,  afford  a much  more  satisfactory  explanation 
of  this  physiological  problem. 

The  rays  of  light  which  come  from  a very  near  object,  are 
very  divergent:  the  eye  would  want  the  refracting  power  neces- 
sary to  collect  them  into  one,  if  the  pupil,  contracting  by  the 
enlargement  of  the  iris,  did  not  throw  off  the  more  divergent 
rays,  or  those  which  form  the  circumference  of  the  luminous 
cone.  Then,  those  which  form  the  centre  of  the  cone,  and  which 
need  but  a much  smaller  refraction  for  their  re-union  on  a 
single  point  of  the  retina,  are  alone  admitted  by  the  straitened 
opening.  When,  on  the  contrary,  we  look  at  a distant  object 


OF  SENSATIONS. 


318 

from  which  rays  are  given  out,  already  very  convergent,  and 
which  need  but  a small  refraction  to  bring  them  towards  the 
perpendicular,  we  dilate  the  pupil,  in  order  to  admit  the  more 
divergent  rays,  which,  when  collected,  will  give  the  image  of 
the  object.  In  this  respect,  very  small  bodies  are  on  the  same 
footing  as  those  at  a great  distance. 

Though  the  image  of  every  object  is  traced  at  the  same  time 
in  both  our  eyes,  we  have  but  one  sensation,  because  the  two 
sensations  are  in  harmony  and  are  blended  and  serve  only,  one 
aiding  the  other,  to  make  the  impression  stronger  and  more 
durable.  It  has  long  been  observed,  that  the  sight  is  more  pre- 
cise and  correct  when  we  use  only  one  eye,  and  Jurine  thinks 
that  the  power  of  the  two  eyes  united  exceeds  only  by  one-thir- 
teenth, that  of  a single  eye.  The  correspondence  of  affection 
requires  the  direction  of  the  optical  axes  on  the  same  objects, 
and  be  that  direction  ever  so  little  disturbed,  we  see  really 
double,  which  is  what  happens  in  squinting. 

If  the  eyes  are  too  powerfully  refractive,  either  by  the  too 
great  convexity  of  the  cornea  and  the  crystalline,  the  greater 
density  of  the  humours,  or  the  excessive  depth  of  the  ball,  the 
rays  of  light,  too  soon  re-united,  diverge  anew,  fall  scattering 
on  the  retina,  and  yield  only  a confused  sensation.  In  this  de- 
fect of  sight  called  myopia^  the  eye  distinguishes  only  very 
near  objects,  giving  out  rays  of- such  extreme  divergence  as  to 
require  a very  powerful  refractor.  In  presbytia^  on  the  other 
hand,  the  cornea  too  much  flattened,  the  crystalline  little  con- 
vex, or  set  too  deeply,  the  humours  too  scanty,  are  the  cause 
that  the  rays  are  not  yet  collected  when  they  fall  upon  the  re- 
tina, so  that  none  but  very  distant  objects  are  distinctly  seen, 
because  the  very*  convergent  rays  they  give  out,  have  no  need 
of  much  refraction. 

Myopia  is  sometimes  the  effect  of  the  habit  which  some  chil- 
dren get,  of  looking  very  close  at  objects  which  catch  their  at- 
tention. The  pupil  then  becomes  accustomed  to  great  constric- 
tion, and  dilates  afterwards  with  difficulty.  It  is  obvious,  that, 
to  correct  this  vicious  disposition,  you  must  show  the  child 

The  author  means  *'  scarcely  divergent.”  T. 


OF  SENSATIONS.  3^9 

distant  objects  which  will  strongly  engage  his  curiosity,  and 
keep  him  at  some  distance  from  every  thing  he  looks  at. 

The  sensibility  of  the  retina,  on  some  occasions,  arises  to  such 
excess,  that  the  eye  can  scarcely  bear  the  impression  of  the 
faintest  light.  Nyctalopes^  such  is  the  name  given  to  those  af- 
fected with  this  disorder,  distinguish  objects  amidst  the  deep- 
est darkness;  a few  rays  are  sufficient  to  impress  their  organ. 

It  is  related  that  an  English  gentleman,  shut  up  in  a dark 
dungeon,  came  gradually  to  distinguish  all  it  contained:  when 
he  returned  to  the  light  of  day,  of  which  he  had  in  some  sort 
lost  the  habit,  he  could  not  endure  its  splendor;  the  edges  of 
the  pupil,  before  extremely  dilated,  became  contracted  to  such 
a degree,  as  entirely  to  efface  the  opening. 

When,  on  the  other  hand,  the  retina  has  little  sensibility,  strong 
day  light  is  requisite  to  sight.  This  injury  of  vision,  known  by 
the  name  of  Hemeralopia^,  may  be  considered  as  the  first  step 
of  total  paralysis  of  the  optic  nerve,  or  gutta  serena.  It  may 
arise  from  any  thing  that  can  impair  the  sensibility  of  the  retina. 
Saint-Yves  relates,  in  his  work  on  diseases  of  the  eyes,  many 
cases  of  hemeralopia.  The  subjects  were  chiefly  workmen  em- 
ployed at  the  Hotel  des  Monnoies,  in  melting  the  metals.  Th« 
inhabitants  of  the  northern  regions,  where  the  earth  is  covered 
with  snow,  great  part  of  the  year,  become  at  an  early  age  he- 
meralopes.  Both  contract  this  weakness,  from  their  eyes  being 
habitually  fatigued  by  the  splendor  of  too  strong  a light. 

Finally,  in  order  to  the  completion  of  the  mechanism  of  vision, 
it  is  requisite  that  all  parts  of  the  eye  be  under  certain  condi- 
tions, the  want  of  which  is  more  or  less  troublesome.  It  is  espe- 
cially necessary,  that  the  membranes  and  the  humours  which  the 
rays  of  light  are  to  pass  through,  should  be  perfectly  transparent. 
Thus,  specks  of  the  cornea,  the  closing  of  the  pupil  by  the  pre- 

* I give  to  the  word  nyctalopia  and  hemeralopia  the  same  meaning  as  all  other 
writers  down  to  Scarpa,  who  has  published  the  latest  treatise  on  diseases  of 
the  eyes.  This  acceptation  is,  how^ever,  a grammatical  error,  since  of  the  two 
terms,  nyctalopia,  in  its  Greek  roots,  signifies  an  affection  which  takes  away 
sight  during  the  night,  and  hemeralopia,  one  in  which  it  is  lost  during  the  day. 
It  is  accordingly  in  this  sense  that  they  are  used  by  the  father  of  physic.  I owe 
this  remark  to  Dr.  Roussille  Chamseru,  who  has  carefully  verified  the  text  of 
Hippocrates  in  the  MSS.  of  the  Imperial  library. 


32© 


OF  SENSATIONS. 


servation  of  the  membrane  which  stops  that  opening  during  the 
first  months  of  the  life  of  the  fcEtus;  cataract,  an  affection  which 
consists  in  the  opacity  of  the  crystalline  lens  or  its  capsule;  the 
glaucoma,  or  defect  of  transparency  in  the  vitreous  humour, 
weaken  or  altogether  destroy  sight,  by  impeding  the  passage  of 
the  rays  to  the  retina.  This  membrane  itself  must  be  of  tempered 
sensibility  to  be  suitably  affected  by  their  contact.  The  choroid, 
the  concavity  of  which  it  fills,  must  present  a coating  black 
enough  to  absorb  the  rays  that  pass  through  it.  It  is  to  the  sen- 
sible decay  of  the  dye  of  the  choroid  in  advancing  years,  as 
much  as  to  the  collapsing,  induration,  and  discolouring  of  dif- 
ferent parts  of  the  eye,  and  the  impaired  sensibility  of  the  retina 
from  long  use,  that  we  ascribe  the  confusion  and  weakness  of 
sight  in  old  people.  The  extreme  delicacy  of  the  eyes  of  Albinos 
proves  equally  the  necessity  of  the  absorption  of  light,  by  the 
black  coating  which  covers  the  choroid. 

The  eyes  are,  of  all  the  organs  of  sense,  those  which  are  the 
most  developed  in  a new-born  child.  They  have  then  nearly  the 
bulk  w'hich  they  are  to  retain  during  life.  Hence  it  happens 
that  the  countenance  of  children,  whose  eyes  are  proportionally 
larger,  is  seldom  disagreeable,  because  it  is  chiefly  in  these 
organs  that  physiognomy  seeks  expression.  Might  we  not  say, 
that  if  nature  sooner  completes  the  organ  of  sight,  it  is  because 
the  changes  which  it  produces  on  the  rays  of  light,  arising  purely 
from  a physical  necessity,  the  perfection  of  the  instrument  was 
required  for  the  exercise  of  the  sense? 

The  eyes  are  not  immoveable  in  the  place  they  occupy.  Drawn 
into  very  various  motions  by  four  recti  muscles,  and  two  oblique^ 
they  direct  themselves  towards  all  objects  of  which  we  wish  to 
take  cognizance;  and  it  is  observed,  that  there  is,  between  the 
muscles  which  move  the  two  eyes,  such  a correspondence  of  ac- 
tion, that  these  organs  turn  at  once  the  same  way,  and  are  di- 
rected, at  once,  towards  the  same  object,  in  such  a manner,  that 
the  visual  axes  are  exactlv  parallel.  It  some  times  happens, 
that  this  harmony  of  motion  is  disturbed,  and  thence  squinting, 
an  aflfection,  which  depending,  almost  always,  on  the  unequal 
force  of  the  muscles  of  the  eye,  may  be  distinguished  into  as 
many  species  as  there  are  muscles  which  can  draw  the  globe  of 
the  eye  into  their  direction,  when  from  any  cause,  they  become 


OF  SENSATIONS. 


32i 


possessed  of  a predominating  ppwer.  Buffon  has  further  as-» 
signed,  as  a cause  of  squinting,  the  different  aptitude  of  the 
eyes  to  be  affected  by  light.  According  to  this  celebrated  na- 
turalist, it  may  happen,  th  .t  one  of  the  e>es  being  originally  of 
greater  sensibility,  the  child  will  close  the  weaker  to  use  the 
stronger,  which  is  yet  strengthened  by  exercise,  whilst  repose 
still  weakens  the  one  which  remains  in  inaction.  The  examina- 
tion of  a great  many  young  people,  who  had  fallen  under  mili- 
tary conscription,  and  claimed  exemption  on  the  score  of  infir- 
mities, has  shown  me  that  squinting  is  constantly  connected  with 
the  unequal  power  of  the  eyes.  Constantly,  the  inactive  eye  is 
the  weakest,  almost  useless,  and  it  was  quite  a matter  of  neces- 
sity that  the  diverging  globe  should  be  thus  neutralized^  else  the 
image  it  would  have  sent  to  the  brain,  different  from  that  which 
the  sound  eye  gives,  would  have  introduced  confusion  into  the 
visual  functions.  The  squinting  eye,  being  inactive,  falls  by  de- 
grees into  that  state  of  debility,  from  default  of  exercise,  which 
Brown  has  so  well  called  indirect  debility. 

The  sense  of  sight  appears  to  me  much  rather  to  deserve  the 
name  which  J.  J.  Rousseau  has  given  to  that  of  smell,  of  sense 
of  the  imagination.  Like  that  brilliant  faculty  of  the  soul,  the 
sight,  which  furnishes  us  with  ideas  so  rich  and  varied,  is  liable 
to  betray  us  into  many  errors.  It  may  be  doubted,  whether  it 
gives  the  notion  of  distance,  since  the  boy  couched  by  Chesel- 
den,  conceived  every  thing  he  saw  to  touch  his  eye.  It  exposes 
us  to  false  judgments  on  the  form  and  size  of  objects;  since 
agreeably  to  the  laws  of  optics,  a square  tower  seen  at  a dis- 
tance, appears  to  us  round;  and  very  lofty  trees  seen  also  very 
far  off,  seem  no  taller  than  the  shrubs  near  us.  A body,  moving 
with  great  rapidity,  appears  to  us  motionless,  &c.  It  is  from  the 
touch  that  we  gain  the  correction  of  these  errors,  which  Con- 
dillac, in  his  Treatise  on  Sensation,  has  perhaps  exaggerated. 

CXX.  The  organ  of  sight,  in  different  animals,  varies  accord- 
ing to  the  medium  in  which  they  live;  thus,  in  birds  which  fly  in 
the  higher  regions  of  the  air,  there  is  an  additional  and  very  re- 
markable eye-lid;  this  is  particularly  the  case  with  the  eagle, 
which  is  thus  enabled  to  look  at  the  sun,  and  with  night  birds, 
whose  very  delicate  eye  it  seems  to  protect  from  the  effects  of 
too  strong  a light.  In  birds,  likewise,  there  is  a copious  secretion 

2 S 


322 


OF  SENSATIONS. 


of  tears,  the  medium  in  which  they  live  causing  a considerable 
evaporation.  The  greater  part  of  fishes,  on  the  contrary,  have 
no  moveable  eye-lid,  and  their  eyes  are  not  moistened  by  tears, 
as  the  water  in  which  they  are  immersed  answers  the  same  pur- 
pose. In  some  fishes,  however,  the  eyes  are  smeared  with  an 
unctuous  substance,  calculated  to  prevent  the  action  of  the  water 
on  the  organ. 

The  globe  of  the  eye  in  birds,  is  remarkable  by  the  convexity 
of  the  cornea  which  is  sometimes  a complete  hemisphere;  hence 
it  possesses  a considerable  power  of  refraction.  This  power  of 
refraction  appears  to  be  very  weak  in  fishes,  the  fore  part  of 
their  eyes  being  very  much  flattened;  but  the  water  in  which 
they  live  made  it  unnecessary  that  they  should  have  an  aqueous 
humour,  for  the  density  of  this  fluid  being  nearly  the  same  as 
that  of  water,  it  would  not  have  produced  any  refraction:  be- 
sides, being,  in  sea  fish,  of  inferior  density  to  that  of  salt  water, 
it  would  have  broken  the  rays  of  light,  by  making  them  diverge 
from  the  perpendicular.  In  fact,  the  refractive  power  of  a me- 
dium is  never  but  a relative  quantity;  the  degree  of  refraction  is 
not  determined  by  the  density  of  the  medium,  but  by  the  differ- 
ence of  density  between  it  and  the  medium  that  is  next  to  it.  To 
make  up  for  the  flatness  of  the  cornea  occasioned  by  the  small 
quantity,  or  even  by  the  absence  of  aqueous  humour,  fishes  have 
a very  dense  and  spherical  crystalline  humour,  the  spherical 
part  of  which  forms  a part  of  a small  sphere. 

The  eyes  of  birds,  whose  cornea  is  thrust  out  by  a very  co- 
pious aqueous  humour,  possess,  in  consequence  of  the  presence 
of  this  fluid,  a very  considerable  power  of  refraction;  the  air,  in 
the  higher  regions  of  the  air,  owing  to  its  extreme  rarefaction, 
being  but  little  calculated  to  approximate  the  rays  of  light. 

The  pupil  admits  of  greater  dilatation  in  the  cat,  ifl  the  owl, 
in  night  birds,  and  in  general  in  all  animals  that  see  in  the  dark. 
The  sensibility  of  the  retina  appears,  likewise,  greater  in  those 
animals;  several  of  them  appear  incommoded  by  the  light  of  day, 
and  never  pursue  their  prey  but  in  the  most  obscure  darkness. 

The  crystalline  humour  of  several  aquatic  fowls,  as  the  cor- 
morant’s, is  spherical  like  that  of  fishes,  and  this  is  not,  as  will  be 
mentioned  hereafter,  the  only  peculiarity  of  structure  in  these 
kind  of  amphibious  animals.  Lastly,  the  choroid  of  some  ani- 


OF  SENSATIONS. 


323 

mals,  more  easily  separated  into  two  distinct  laminae,  than  that 
of  man,  presents,  at  the  bottom  of  the  eye,  instead  of  a darkish 
uniformly  diifused  coating,  a pretty  extensive  spot  of  various 
colours,  and  in  some,  most  beautiful  and  brilliant.  It  is  not  easy 
to  say  what  is  the  use  of  this  coloured  spot,  known  by  the  name 
of  tapetum. 

The  rays  of  light,  reflected  by  this  opake  substance,  must, 
in  passing  through  the  eye,  cross  those  which  are  entering  at  the 
same  time;  they  must  consequently  prevent  distinct  vision,  or 
at  least  impair  the  impression,  in  a manner  which  it  is  impossi- 
ble to  determine.  It  has  been  said,  that  the  lower  animals,  pro- 
vided with  less  perfect  and  often  less  numerous  senses  than 
those  of  man,  must  have  different  ideas  of  the  universe;  is  it 
not,  likewise,  probable,  that  in  consequence  of  the  indistinct 
vision  occasioned  by  the  reflection  from  the  tapetum,  they  may 
entertain  erroneous  and  exaggerated  notions  of  the  power  of 
man?  And  notwithstanding  the  power  granted  to  man  by  the 
Creator  over  the  lower  animals,  as  we  are  told  in  the  book  of 
Genesis,  is  it  probable  that  those  which  nature  has  gifted  with 
prodigious  strength  or  with  offensive  weapons,  would  obey  the 
Lord  of  the  creation  if  they  saw  him  in  his  feeble  and  destitute 
condition,  in  a word,  such  as  he  is? 

The  head  of  insects  with  numerous  eyes,  is  joined  to  their 
body,  and  moves  along  with  it;  their  existence  is,  besides,  so 
frail,  that  it  was  requisite  that  nature  should  furnish  them  abun- 
dantly with  the  means  of  seeing  those  objects  which  may  be  in- 
jurious to  them.  We  shall  not  enter  any  farther  into  these  re- 
marks relative  to  the  differences  in  the  organ  of  sight,  in  the  va- 
rious kinds  of  animals.  More  ample  details  on  this  subject  be- 
long, in  an  especial  manner,  to  comparative  anatomy. 

CXXI.  Of  the  organ  of  hearing.  Of  sound.  Sound  is  not, 
like  light,  a body  having  a distinct  existence;  we  give  the  name 
of  sound  to  a sensation  which  we  experience  whenever  the  vi- 
brations of  an  elastic  body  strike  our  ears.  All  bodies  are  capa- 
ble of  producing  it,  provided  their  molecules  are  susceptible  of 
a certain  degree  of  re-action  and  resistance.  When  a sonorous 
body  is  struck,  its  integrant  particles  experience  a sudden  con- 
cussion, are  displaced  and  oscillate  with  more  or  less  rapidity. 
This  tremulous  motion  is  communicated  to  the  bodies  applied 


OP  SENSATIONS. 


324 

to  its  surface;  if  we  lay  our  hand  on  a bell  that  has  been  struck 
by  its  clapper,  we  feel  a certain  degree  of  this  trembling.  The 
air,  which  envelops  the  sonorous  body,  receives,  and  transmits 
its  vibrations  with  the  more  effect  from  being  more  elastic. 
Hence,  it  is  observed  that,  cseteris  paribus,  the  voice  is  heard  at 
a greater  distance  in  winter,  when  the  air  is  dry  and  condensed 
by  the  cold. 

The  sonorous  rays  are  merely  series  of  particles  of  air,  along 
which  the  vibration  is  transmitted  from  the  sonorous  body,  to 
the  ear  which  perceives  the  noise  occasioned  by  its  percussion. 
These  molecules  participate  in  the  vibrations  which  are  com- 
municated to  them;  they  change  their  form  and  situation,  in 
proportion  as  they  are  nearer  to  the  body  that  is  struck,  and  vice 
versa;  for  sound  becomes  weaker  in  proportion  to  the  increase 
of  distance.  But  this  oscillatory  motion  of  the  aerial  molecules, 
should  be  well  distinguished  from  that  by  which  the  atmosphere, 
agitated  by  the  winds,  is  transported  and  changes  its  situation. 
And  in  the  same  manner  as  the  balance  of  a pendulum  moves 
incessantly  within  the  same  limits,  so  this  oscillatory  motion 
affects  the  molecules  of  the  air  within  the  space  which  they  oc- 
cupy, so  that  they  move  to  and  fro  during  the  presence  or 
the  absence  of  the  vibration.  The  atmospherical  air,  when  set 
in  motion  in  a considerable  mass  at  a time,  produces  no  sound, 
unless  in  its  course  it  meets  with  a body  which  vibrates  from 
the  percussion  which  it  experiences. 

The  force  of  sound  depends,  entirely,  on  the  extent  of  the 
vibrations  experienced  by  the  molecules  of  the  sonorous  body. 
In  a large  bell  struck  violently,  the  agitation  of  the  molecules  is 
such,  that  they  are  transmitted  to  considerable  distances,  and 
that  the  form  of  the  body  is  evidently  changed  by  it.  Acute  or 
grave  sounds  are  produced  by  the  greater  or  smaller  number  of 
vibrations  in  a given  time,  and  the  vibrations  will  be  more 
numerous,  the  smaller  the  length  and  diameter  of  the  body. 
Two  catgut  strings,  of  the  same  length  and  thickness,  and  with 
an  equal  degree  of  tension,  will  vibrate  an  equal  number  of 
times  in  a given  time,  and  produce  the  same  sound.  This  in  mu- 
sic is  called  unison.  If  one  of  the  strings  is  shortened  by  one 
half,  it  vibrates  as  often  again  as  the  other,  and  gives  out  a 
sound  more  acute,  or  higher  by  one  octave.  The  same  result  may 


OF  SENSATIONS. 


325 


be  obtained  by  reducing  the  string  one  half  of  its  original  thick- 
ness, without  taking  from  its  length.  The  vibrations  will,  in  the 
same  manner,  be  accelerated  by  giving  a greater  degree  of  ten- 
sion to  the  sonorous  cord.  The  difference  of  the  sounds  pro- 
duced by  a bass,  a harp,  or  any  other  stringed  instrument,  de- 
pends on  the  unequal  tension,  length  and  size  of  the  strings. 

This  division  of  the  elementary  sound  is  an  act  of  the  under- 
standing, which  distinguishes  in  a noise,  apparently  monotonous, 
innumerable  varieties,  and  shades  expressed  by  signs  of  conven- 
tion, But  in  the  same  manner  as  light,  refracted  by  a prism, 
presents  innumerable  intermediate  shades  between  the  seven 
primitive  colours,  and  as  the  transition  is  gradual  from  the  one 
to  the  other  of  these  colours;  so,  the  division  of  the  primitive 
sound  into  seven  tones,  expressed  by  notes,  is  not  absolute,  and 
there  are  a number  of  intermediate  sounds  which  augment  or 
diminish  their  value,  &c. 

Sound  has,  therefore,  been  analysed  as  well  as  light;  the  use 
of  the  ear  with  regard  to  sound,  corresponds  to  that  of  the  prism 
with  regard  to  light;  and  the  modifications  of  which  sound  is 
capable,  are  as  numerous  and  as  various  as  the  shades  between 
the  primitive  colours. 

Sound  is  propagated  with  less  velocity  than  light.  The  report 
of  a cannon  fired  at  a distance  is  heard  only  a moment  after  the 
eye  has  perceived  the  flash  of  the  explosion.  Its  rays  diverge 
and  are  reflected,  like  those  of  light,  when  they  meet  with  an 
obstacle  at  an  angle  equal  to  that  of  incidence.  The  force  of 
sound,  like  that  of  light,  may  be  increased  by  collecting  and  con- 
centrating its  rays.  The  sonorous  ra)'s  which  strike  a hard  and 
elastic  body,  when  reflected  by  it,  impart  to  it  a vibratory  mo- 
tion, giving  rise  to  a secondary  sound,  which  increases  the  force 
of  the  primitive  sound. 

When  these  secondary  sounds,  produced  by  the  percussion 
of  a body  at  a certain  distance,  reach  the  ear,  they  give  rise  to 
what  is  called  an  echo.  Who  is  unacquainted  with  the  ingenious 
allegory,  by  which  its  nature  is  expressed  in  ancient  mythology, 
in  which  echo  was  called  daughter  of  the  air  and  of  the  earth? 

CXXII,  Of  the  organ  and  mechanism  of  hearing.  The  organ 
of  hearing  in  man,  consists  of  three  very  distinct  parts;  the  one 
placed  externally,  is  intended  to  collect  and  to  transmit  the  song- 


326 


OF  SENSATIONS. 


rous  rays  which  are  modified  in  passing  along  an  intermediate 
cavity,  betM'een  the  external  and  internal  ear.  It  is  within  the 
cavities  of  this  third  part  of  the  organ,  excavated  in  the  sub- 
stance of  the  petrous  portion  of  the  bone,  that  the  nerve  destined 
to  the  preception  of  sound  exclusively  resides.  The  external 
ear  and  the  meatus  auditorius  externus  may  be  compared  to  an 
acoustic  trumpet,  the  broad  part  of  which,  represented  by  the 
concha,  collects  the  sonorous  rays  which  are  afterwards  trans- 
mitted along  the  contracted  part,  represented  by  the  meatus  ex- 
ternus. The  concha  contains  several  prominences  separated  by 
corresponding  depressions;  its  concave  part  is  not  wholly  turned 
outward;  in  those  who  have  not  laid  their  ears  fiat  against  the 
side  ol'  the  head  by  tight  bandages,  it  is  turned  slightly  forward; 
and  this  arrangement,  favourable  to  the  collecting  of  sound,  is 
particularly  remarkable  in  savages,  whose  hearing,  it  is  well 
known,  is  remarkable  delicate.  The  base  of  the  concha  consists 
of  a fibro-cartilaginous  substance,  thin,  elastic,  calculated  to  re- 
fiect  sounds,  and  to  increase  their  strength  and  intensity  by  the 
vibrations  to  which  it  is  liable.  This  cartilage  is  covered  by  a 
very  thin  skin,  under  which  no  fat  is  collected  that  could  impair 
its  elasticity;  these  prominences  are  connected  together  by  small 
muscles;  these  may  relax  it  by  drawing  the  projections  together, 
and  thus  place  it  in  unison  with  the  acute  or  grave  sounds. 
These  small  muscles  within  the  external  ear,  as  the  musculi 
helicis  major  and  minor,  the  tragicus  and  anti-tragicus,  and  the 
transversus  auris,  are  like  the  muscles  on  the  outer  part  of  the 
ear,  stronger  and  more  marked  in  timid  animals  with  long  ears. 
In  the  hare,  the  fibres  of  these  muscles  are  most  distinctly 
marked;  their  action  is  most  apparent  in  this  feeble  and  fearful 
animal,  which  has  no  resource  but  in  fiight  against  the  dangers 
which  incessantly  threaten  his  existence,  and  which  required 
that  he  should  receive  early  intimation  of  approach  of  dan- 
ger; hence  hares  have  the  power  of  making  their  ears  assume 
various  forms,  of  shaping  them  into  more  advantageous  trum- 
pets, of  moving  them  in  every  direction,  of  directing  them 
towards  the  quarter  from  which  the  noise  proceeds,  so  as  to 
meet  the  sounds  and  collected  the  slightest. 

The  form  of  the  external  ear  is  not  sufficiently  advantageous 
in  man,  whatever  Boerhaave  may  have  said  to  the  contrary,  to 


OP  SENSATIONS. 


227 

«nable  all  the  sonorous  rays,  which  in  striking  against  it,  are 
reflected  at  an  angle  equal  to  that  of  their  incidence,  to  be  di- 
rected towards  the  meatus  auditorius  externus.  United,  for  the 
most  part,  into  a single  fasciculus,  and  directed  towards  the 
concha,  they  penetrate  into  the  meatus  auditorius  externus,  and 
the  tremulous  motions  which  they  excite  in  its  osso-cartilagi- 
nous  parietes,  contribute  to  increase  their  force.  On  reaching 
the  bottom  of  the  meatus,  they  strike  against  the  membrana 
tympani,.  a thin  and  transparent  septum,  stretched  between  the 
bottom  of  the  meatus  and  the  cavity  in  which  the  small  bones 
of  the  ear  are  lodged.  These  small  bones  form  a chain  of  bone 
which  crosses  the  tympanum  from  without  inward,  and  which 
extends  from  the  membrana  tympani  to  that  which  connects  the 
base  of  the  stapes  to  the  edge  of  the  fenestra  ovalis. 

An  elastic  air,  continually  renewed  by  the  Eustachian  tube, 
fills  the  cavity  of  the  tympanum;  small  muscles  attached  to  the 
malleus  and  stapes  move  these  bones,  or  relax  the  membranes 
to  which  they  are  attached,  and  thus  institute  a due  relation 
between  the  organ  of  hearing  and  the  sounds  which  strike  it.  It 
will  be  easily  conceived,  that  the  relaxation  of  the  membrana 
tympani,  effected  by  the  action  of  the  anterior  muscle  of  the 
malleus,  must  weaken  acute  sounds,  while  the  tension  of  the 
same  membrane,  by  the  internal  muscles  of  the  same  bone,  must 
increase  the  force  of  the  grave  sounds.  In  the  same  manner  as 
the  eye,  by  the  contraction  or  dilatation  of  the  pupil,  accommo- 
dates itself  to  the  light,  so  as  to  admit  a greater  or  smaller  num- 
ber of  its  rays,  according  to  the  impression  which  they  produce: 
so  by  the  relaxation  or  tension  of  the  membrane  of  the  tympa- 
num, or  of  the  fenestra  ovalis,  the  ear  reduces  or  increases  the 
strength  of  sounds  whose  violence  would  affect  its  sensibility  in 
a painful  manner,  or  whose  impression  would  be  insufficient. 
The  iris,  and  the  muscles  of  the  stapes  and  of  the  malleus 
are,  therefore,  the  regulators  of  the  auditory  and  visual  impres- 
sion; there  is  as  close  a sympathetic  connexion  between  these 
muscles  and  the  auditory  nerve,  as  between  the  iris  and  the 
retina.  The  air  which  fills  the  tympanum  is  the  true  vehicle  of 
sound;  this  air  diffuses  itself  over  the  mastoid  cells,  the  use  of 
which  is  to  augment  the  dimensions  of  the  tympanum,  and  the 


328 


OF  SENSATIOXS. 


force  and  extent  of  the  vibrations  which  the  air  experiences 
within  it. 

These  vibrations,  transmitted  by  the  membrana  tympani,  are 
communicated  to  those  membranes  which  cover  the  fenestra 
ovalis  and  the  fenestra  rotunda;  then,  by  means  of  these,  to  the 
fluid  which  fills  the  different  cavities  of  the  internal  ear,  and  in 
which  lie  the  soft  and  delicate  filaments  of  the  auditory  nerve, 
or  of  the  portio  mollis  of  the  seventh  pair. 

The  agitation  of  the  fluid  affects  these  nerves,  and  determines 
the  sensation  of  grave  or  acute  sounds,  according  as  they  are 
slower  or  more  rapid.  It  appears  that  the  diversity  of  sounds 
should  rather  be  attributed  to  the  more  or  less  rapid  oscillations, 
and  to  the  undulations  of  the  lymph  of  Cotunni,  than  to  the  im- 
pressions on  filaments,  of  different  lengths,  of  the  auditory 
nerve.  These  nervous  filaments  are  too  soft  and  too  slender  to 
be  traced  to  their  extreme  terminations.  It  is,  however,  proba- 
ble, that  the  various  forms  of  the  internal  ear,  (the  semi  circular 
canals,  the  vestibule,  and  the  cochlea,')  have  something  to  do 
with  the  diversity  of  sounds.  It  must  also  be  observed,  that  the 
cavities  of  the  ear  are  contained  in  a bony  part,  harder  than  any 
other  substance  of  the  same  kind,  and  well  fitted  to  maintain,  or 
even  to  augment  by  the  re-action  of  which  it  is  capable,  the 
force  of  the  sonorous  rays. 

The  essential  part  of  the  organ  of  hearing,  that  which  appears 
exclusively  employed  in  receiving  the  sensation  of  sounds  is, 
doubtless,  that  which  exists  in  all  animals  endowed  with  the  fa- 
culty of  hearing.  This  part  is  the  soft  pulp  of  the  auditory 
nerve,  floating  in  the  midst  of  a gelatinous  fluid,  contained  in  a 
thin  and  elastic  membranous  cavity.  It  is  found  in  all  animals, 
from  man  to  the  sepiae.  In  no  animal  lower  in  the  scale  of  ani- 
mation, has  an  organ  of  hearing  been  met  with,  although  some 
of  these  inferior  animals  do  not  seem  to  be  absolutely  destitute 
of  that  organ.  This  gelatinous  pulp  is,  in  the  lobster,  contained 
in  a hard  and  horny  covering.  In  animals  of  a higher  order,  its 
internal  part  is  divided  into  various  bony  cavities.  In  birds, 
there  is  interposed  a cavity,  between  that  which  contains  the 
nerve  of  hearing  and  the  outer  part  of  the  head;  in  man  and  in 
quadrupeds,  the  organ  of  hearing  is  very  complicated;  it  is  en- 


OF  SENSATIONS. 


329 

closed  in  an  osseous  cavity,  extremely  hard,  situated  at  a consi- 
derable depth,  and  separated  from  the  outer  part  of  the  head, 
by  a cavity  and  a canal  along  which  the  sonorous  rays  are  trans- 
mitted, after  having  been  collected  into  fasciculi  by  trumpets 
situated  on  the  outside. 

This  kind  of  natural  analysis  of  the  organ  of  hearing,  is  well 
calculated  to  give  accurate  notions  on  the  nature  and  import- 
ance of  the  functions  fulfilled  by  each  of  its  parts.  But  in  the 
investigation  of  the  uses  and  of  the  relative  importance  of  the 
auditory  apparatus,  morbid  anatomy  furnishes  data  of  an  equal 
value  with  those  obtained  from  comparative  anatomy. 

CXXllI.  The  external  ear  may  be  removed,  with  impunity, 
in  man,  and  even  in  animals  in  which  its  form  is  more  advan- 
tageous; the  hearing  is  at  first  impaired,  but  at  the  end  of  a few 
days  recovers  its  wonted  delicacy.  The  complete  obliteratioa 
of  the  meatus  auditorius  externus,  is  attended  with  complete 
deafness.  It  is  not  essentially  necessary  for  the  mechanism  of 
hearing,  that  the  membrana  tympani  should  be  whole;  persons 
in  whom  it  has  been  accidentally  ruptured,  can  force  out  smoke 
at  their  ears,  without  losing  the  power  of  hearing;  it  may  be 
conceived,  however,  that  if  instead  of  having  merely  a small 
opening  that  would  not  prevent  its  receiving  the  impression  of 
the  sonorous  rays,  nor  its  being  acted  upon  by  the  handle  of  the 
malleus,  the  membrana  tympani  were  almost  entirely  destroyed, 
deafness  would  be  the  almost  unavoidable  consequence.  If,  in 
consequence  of  the  obstruction  of  the  Eustachian  tube,  the  air  in 
the  tympanum  is  not  renewed,  it  loses  its  elasticity  and  com- 
bines with  the  mucus  within  the  tympanum.  The  cavity  of  the 
tympanum  is  then  in  the  same  condition  as  an  exhausted  re- 
ceiver, in  which  the  sonorous  rays  are  transmitted  with  diffi- 
culty. It  has  been  thought,  that  the  use  of  the  Eustachian  tube 
was,  not  only  to  renew  the  air  contained  in  the  tympanum,  but 
also  to  transmit  the  sonorous  rays  into  that  cavity.  In  listening 
attentively,  we  slightly  open  our  mouth,  in  order,  it  is  said,  that 
the  sound  may  pass  from  this  cavity  into  the  pharynx  and  thence 
reach  the  organ  of  hearing.  This  explanation  is  far  from  satis- 
factory, for  the  obliteration  of  the  meatus  auditorius  externus 
is  attended  with  complete  deafness,  which  would  not  happen,  if 

2 T 


OF  SENSATIONS. 


3S0 

the  Eustachian  tubes  transmitted  the  sonorous  rays.  When  a 
man  listens  attentively,  and  with  his  mouth  open,  the  condyles 
of  the  lower  jaw,  situated  in  front  of  the  external  auditory  mea- 
tus, being  depressed  and  brought  forward,  the  openings  are 
evidently  enlarged,  as  may  be  ascertained  by  putting  the  little 
linger  into  one’s  ear  at  the  moment  of  depressing  the  lower 
jaw.  The  luxation  of  the  small  bones  of  the  ear,  or  even  their 
complete  destruction  does  not  occasion  deafness,  the  only  con- 
sequence is  a confusion  in  the  perception  of  sounds.  When, 
however,  the  stapes,  the  base  of  which  rests  on  the  greatest  part 
of  the  fenestra  ovalis,  or  when  the  thin  membrane  which  closes 
the  fenestra  ovalis,  or  when  that  which  closes  the  fenestra  ro- 
tunda Is  destroyed,  deafness  takes  place,  in  consequence  of  the 
escape  of  the  fluid  which  fills  the  cavities  in  which  the  auditory 
nerve  is  distributed. 

The  existence  of  this  fluid  appears  essential  to  the  mechan- 
ism of  hearing,  either  from  its  keeping  the  nerves  in  the  soft 
and  moist  state  required  for  the  purpose  of  sensation,  or  from 
its  transmitting  to  them  the  undulatory  motion  with  which  it 
is  agitated. 

The  deafness  of  old  people,  which,  according  to  authors,  de- 
pends on  the  impaired  sensibility  of  the  nerves,  whose  excita- 
bility has  been  exhausted  by  impressions  too  frequently  repeat- 
ed, appears,  sometimes,  to  be  occasioned  by  a deficiency  of  this 
humour,  and  by  the  want  of  moisture  in  the  internal  cavities  of 
the  ear.  During  the  severe  winter  of  1798,  Professor  Pinel  open- 
ed, at  the  Hospital  of  Salpetriere,  the  skulls  of  several  women 
who  died  at  a very  advanced  age,  and  who  had  been  deaf  for 
several  years.  The  cavities  of  the  internal  ear  were  found  quite 
empty;  they  contained  an  isicle  in  younger  subjects  who  had 
possessed  the  power  of  hearing. 

Deafness  may,  likewise,  be  produced  by  a palsy  of  the  portio 
mollis  of  the  seventh  pair,  or  by  a morbid  condition  of  the  part 
of  the  brain  from  which  this  nerve  arises.  The  mechanical  ex- 
planation applied  by  Willis  to  the  anomalous  affections  of  the 
organ  of  hearing,  is  inadmissible,  in  those  cases  in  which  that 
organ  is  sensible  only  to  the  impression  of  weak  or  strong 
sounds  acting  together  or  separately. 


OF  SENSATIONS. 


331 


This  author  relates  the  case  of  a woman  who  could  not  hear, 
unless  a great  noise  was  made  near  her,  either  by  beating  a drum 
or  by  ringing  a bell;  because,  says  he,  under  such  circumstances, 
these  loud  noises  determine  in  the  membrana  tympani,  which 
he  supposes  in  a state  of  relaxation,  the  degree  of  tension  re- 
quired to  enable  it  to  vibrate  under  the  impression  of  weaker 
sounds.  This  membrane,  to  present  greater  resistance,  must  be 
put  on  the  stretch  by  the  internal  muscle  of  the  malleus,  or  by 
its  own  contraction.  The  total  absence  of  muscular  fibres  in  the 
membrani  tympani,  in  man,  renders  very  doubtful  this  sponta- 
neous contraction.  Mr.  Home,  however,  has  just  ascertained 
that  the  membrana  tympani  of  the  elephant  is  muscular  and 
contractile.  Admitting  all  these  suppositions,  we  only  substi- 
tute one  difficulty  for  another,  and  it  remains  to  be  shown,  why 
die  more  powerful  sounds  merely  increase  the  tone  of  the  mem- 
brana tympani;  why  they  do  not  become  objects  of  perception 
of  the  organ  of  hearing,  though  they  might  be  expected  to  ren- 
der us  insensible  to  the  perception  of  weaker  sounds. 

CXXIV.  Of  odours.  Chemists  have  long  thought  that  the 
odoriferous  part  of  bodies  formed  a peculiar  principle,  distinct 
from  all  the  other  substances  entering  into  their  composition; 
they  gave  it  the  name  of  aroma;  M.  Fourcroy,  however,  has 
clearly  shown,  that  this  pretended  element  consisted  merely  of 
minute  particles  of  bodies  detached  by  heat  and  dissolved  in  the 
atmosphere,  which  becomes  loaded  with  them  and  conveys  them 
to  the  olfactory  organs.  According  to  this  theory,  all  bodies  are 
odoriferous,  since  caloric  may  sublimate  some  of  the  particles  of 
those  which  are  least  volatile.  Linnaeus  and  Lorry  had  endea- 
voured to  class  odours,  according  to  the  sensations  which  they 
produce*;  M.  Fourcroy  has  been  guided  by  the  chemical  nature 

* Linnaeus  admits  seven  classes  of  odours;  1st  class,  owirosiac  odours,  those 
of  the  rose  and  of  musk  belong  to  this  class;  they  are  characterised  by  their 
tenacity:  2d,  fragrant;  for  example,  the  lily,  the  saffron,  and  jasmine;  they 
fly  off  readily:  3d,  aromatic,  as  thegsmell  of  the  laurel:  4th,  aliaceom,  ap- 
proaching to  that  of  garlic:  5ih,fatid,  as  that  of  valerian  and  fungi:  6\.\\,mrous, 
as  of  poppies  and  opium:  7th,  nauseous,  as  that  of  gourds,  melons,  cucumbers, 
and,  in  general,  all  cucurbitaceous  plants. 

Lorry  admits  only  five  kinds  of  odours,  camphorated,  narcotic,  ethereal,  volatile, 
ficid,  and  alkaline. 

M.  Fourcroy 


OF  SENSATIONS. 


332 

of  substances;  but  however  advantageous  this  last  classification 
may  be,  it  is  difficult  to  include  in  it,  the  infinitely  varied  odours 
which  exhale  from  substances  of  all  kinds,  and  it  is  perhaps  as 
difficult  to  arrange  them  in  classes,  as  the  bodies  from  which 
they  are  produced. 

This  being  laid  down  on  the  nature  of  odours,  it  is  next  ex- 
plained, why  the  atmosphere  becomes  loaded  with  the  greater 
quantity,  the  warmer  and  the  more  moist  it  is.  VVe  know,  that 
in  a flower  garden,  the  air  is  at  no  time  more  loaded  with  frag- 
rant odours,  and  the  smell  is  never  the  source  of  greater  enjoy- 
ment, than  in  the  morning,  when  the  dew  is  evaporating  by  the 
rays  of  the  sun.  It  is,  likewise,  easily  understood,  why  the  most 
pungent  smells  generally  evaporate  very  readily,  as  ether,  al- 
cohol, the  spirituous  tinctures  and  essential  volatile  oils. 

CXXV.  Of  the  organ  of  smell.  The  nasal  fossae,  within 
which  this  organ  is  situated,  are  two  cavities  in  the  depth  of 
the  face  and  extending  backward  into  other  cavities,  called 
frontal,  ethmoidal,  sphenoidal,  palatine,  and  maxillary  sinuses. 

A pretty  thick  mucous  membrane,  always  moist,  and  in  the 
tissue  of  which  the  olfactory  nerves  and  a considerable  number 
of  other  nerves  and  vessels  are  distributed,  lines  the  nostrils  and 
extends  into  the  sinuses  which  communicate  with  them,  and 
covers  their  parietes,  throughout  their  windings  and  promi- 
nences. This  membrane,  called  pituitary.,  is  soft  and  fungous, 
and  is  the  organ  which  secretes  the  mucus  of  the  nose;  it  is 
thicker  over  the  turbinated  bones  which  lie  within  the  olfactory 
cavities;  it  grows  thinner  and  firmer,  in  the  difierent  sinuses. 

The  smell  appears  more  delicate,  in  proportion  as  the  nasal 
fossas  being  more  capacious,  the  pituitary  membrane  covers  a 
greater  space.  The  soft  and  moist  condition  of  this  membrane 
is,  likewise,  essentially  necessary  to  the  perfection  of  this  sense. 
In  the  dog,  and  in  all  animals  which  have  a very  exquisite  sense 
of  smell,  the  frontal,  ethmoidal,  sphenoidal,  palatine,  and  max- 
illary sinuses,  are  prodigiously  capacious,  and  the  parietes  of  the 
skull  are,  in  great  measure,  hollowed  by  these  different  parts  of 
the  olfactory  apparatus;  the  turbinated  bones  are,  likewise,  very 

M.  Fourcroy  admits  the  7n«coui  aroma,  belonging  to  plants  improperly  term- 
ed inodorous:  Oil*!  and  fugacious,  oily  and  volatile,  acid  and  hydro-sulphureous. 


OF  SENSATIONS. 


333 


prominent  in  them,  and  the  grooves  between  them  very  deep; 
lastly,  the  nerves  of  the  first  pair  are  large  in  proportion.  Among 
the  animals  possessed  of  great  delicacy  of  smell,  few  are  more 
remarkable  than  the  hog.  This  impure  animal,  accustomed  to 
live  in  the  most  offensive  smells,  and  in  the  most  disgusting 
filth,  has,  however,  so  very  nice  a smell,  that  it  can  detect  cer- 
tain roots,  though  buried  in  the  earth  at  a considerable  depth. 
In  some  countries  this  quality  is  turned  to  advantage,  and  swine 
are  employed  in  looking  for  trufles.  The  animal  is  taken  to 
those  places  where  they  are  suspected  to  be,  turns  up  the  earth 
in  which  they  are  buried,  and  would  feed  on  them  greedily,  if  the 
herdsmen,  satisfied  with  this  indication,  did  not  drive  them 
away  from  this  substance  intended  for  more  delicate  palates. 

CXXVI.  Of  the  sensation  of  odours.  Do  the  nerves  of  the 
first  pair  alone  give  to  the  pituitary  membrane  the  power  of  re- 
ceiving the  impression  of  smell,  and  do  the  numerous  filaments 
of  the  fifth  pair  merely  impart  to  it  the  general  sensibility  be- 
longing to  other  parts?  This  question  appears  to  require  an 
answer  in  the  affirmative.  The  pituitary  membrane  in  fact  pos- 
sesses two  modes  of  sensibility,  perfectly  distinct,  since  the  one 
of  the  two  may  be  almost  completely  destroyed,  and  the  other 
considerably  increased.  Thus,  in  violent  catarrh,  the  sensibility 
of  the  part  as  far  as  it  relates  to  the  touch  is  very  acute,  since 
the  pituitary  membrane  is  affected  with  pain,  while  the  patient 
is  insensible  to  the  strongest  smells. 

It  seems  probable,  that  the  olfactory  nerves  do  not  extend  into 
the  sinuses,  and  that  these  improve  the  sense  of  smell  merely 
by  retaining,  for  a longer  space  of  time,  a considerable  mass  of 
air  loaded  with  odoriferous  particles.  I have  known  detergent 
injections,  strongly  scented,  thrown  into  the  antrum  highmoria- 
num  by  a fistula  in  the  alveolar  processes,  produce  no  sensation 
of  smell.  A phial  filled  with  a spirituous  liquor  having  been  ap- 
plied to  a fistula  in  the  frontal  sinuses,  gave  no  impression  to 
the  patient.  The  true  seat  of  the  sense  of  smell  is  at  the  most 
elevated  part  of  the  nostrils,  which  the  nose  covers  over  in  the 
form  of  a capital.  There  the  pituitary  membrane  is  moister, 
receives  into  its  tissue  the  numerous  filaments  of  the  first  pair 
of  the  nerves,  which  arising  by  two  roots  from  the  anterior  lobe 


OF  SENSATIONS. 


334 

of  the  brain,  and  from  the  fissure  which  separates  it  from  the 
posterior  lobe,  passes  from  the  cranium  through  the  openings 
of  the  cribriform  plate  of  the  ethmoid  bone,  and  terminates, 
forming,  by  the  expansion  of  its  filaments,  a kind  of  parenchy- 
matous tissue,  not  easily  distinguished  from  that  of  the  mem- 
brane. The  olfactory  papillae  would  soon  be  destroyed  by  the 
contact  of  the  atmospherical  air,  if  they  were  not  covered  over 
by  the  mucus  of  the  nose.  The  use  of  this  mucus  is  not  merely 
to  preserve  the  extremities  of  the  nerves  in  a sentient  state,  by 
preventing  them  from  becoming  dry,  but,  likewise,  to  lessen  the 
too  strong  impression  that  would  arise  from  the  immediate  con- 
tact of  the  odoriferous  particles.  It  perhaps  even  combines  with 
the  odours,  and  these  affect  the  olfactory  organs  only  when  dis- 
solved in  mucus,  as  the  food  in  saliva. 

As  the  air  is  the  vehicle  of  odours,  these  affect  the  pituitary 
membrane  only  when  we  inhale  it  into  the  nostrils.  Hence, 
when  any  odour  is  grateful  to  us,  we  take  in  short  and  frequent 
inspirations,  that  the  whole  of  the  air  which  is  received  into  the 
lungs,  may  pass  through  the  nasal  fossae.  We,  on  the  contrary, 
breathe  through  the  mouth,  or  we  suspend  respiration  altogether, 
when  smells  are  disagreeable  to  us. 

The  sense  of  smell,  like  all  the  other  senses,  is  readily  im- 
pressed on  children,  though  the  nasal  fossae  are  in  them  much 
contracted,  and  though  the  sinuses  are  not  yet  formed.  The 
general  inerease  of  sensibility  at  this  period  of  life,  makes  up 
for  the  imperfect  state  of  the  organization;  and  it  is,  in  this  re- 
spect, with  the  nasal  fossae  as  with  the  auditory  apparatus,  of 
which  an  important  part,  the  meatus  externus,  is  then  not  com- 
pletely evolved.  The  sense  of  smell  is  perfected  by  the  loss  of 
some  of  the  other  senses;  every  body,  for  example,  knows  the 
history  of  the  blind  man,  whom  that  organ  enabled  to  judge  of 
the  continence  of  his  daughter;  it  becomes  blunted  by  the  ap- 
plication of  strong  and  pungent  odours.  Thus,  snuff  changes  the 
quality  of  the  mucus  secreted  by  the  membrane  of  the  nose, 
alters  its  tissue,  dries  its  nerves,  and  in  the  course  of  time  im- 
pairs their  sensibility. 

The  shortness  of  the  distance  between  the  origin  of  the  olfac- 
tory nerves  in  the  brain,  and  their  termination  in  the  nasal  fossse. 


OF  SENSATIONS. 


3.35 

renders  very  prompt  and  easy  the  transmission  of  the  impres-* 
sions  which  they  experience.  This  vicinity  to  the  brain,  induces 
us  to  apply  to  those  nerves,  stimulants  calculated  to  rouse  the 
sensibility  when  life  is  suspended,  as  in  fainting  and  asphyxia. 
The  sympathetic  connexions  between  the  pituitary  membrane 
and  the  diaphragm,  account  for  the  good  effects  of  sternuta- 
tories, in  cases  of  apparent  death. 

CXXVII.  Of  favours.  Flavours  are  no  less  varied  and  no 
less  numerous  than  odours;  and  it  is  as  difficult  to  reduce  them 
to  general  classes  connected  by  analogies,  and  including  the 
whole.*.  Besides,  there  exists  no  element  of  flavour,  any  more 
than  an  odoriferous  principle.  The  flavour  of  fruits  alters  as  they 
ripen,  and  appears  to  depend  on  the  inward  composition  of 
bodies,  on  their  peculiar  nature,  rather  than  on  the  form  of 
their  nfiolecules;  since  crystals  of  the  same  figure,  but  belonging 
to  different  salts,  do  not  produce  similar  sensations. 

To  affect  the  organ  of  taste,  a body  should  be  soluble  at  the 
ordinary  temperature  of  the  saliva;  all  insoluble  substances  are 
insipid,  and  one  might  apply  to  the  organ  of  taste  this  celebrated 
axiom  in  chemistry;  corpora  non  agunt  nisi  soluta.  If  there  is  a 
complete  absence  of  saliva,  and  if  the  body  that  is  chewed  is 
altogether  without  moisture,  it  will  affect  the  parched  tongue 
only  by  its  tactile,  and  not  at  all  by  its  gustatory  qualities.  The 
substances  which  have  most  flavour,  are  those  which  yield  most 
readily  to  chemical  combinations  and  decompositions;  as  acids, 
alkalies  and  neutral  salts.  When,  in  affections  of  the  digestive 
organs,  the  tongue  is  covered  with  a mucous  or  whitish  fur,  or 
of  a yellowish  or  bilious  colour,  we  have  only  incorrect  ideas 
of  flavours;  the  thinner  or  thicker  coating  prevents  the  immedi* 
ate  contact  of  the  sapid  particles;  when  they  act,  besides,  on  the 
nervous  papillae,  the  impression  which  they  produce  is  lost  in 
that  occasioned  by  the  morbid  contents  of  the  stomach;  hence 
every  aliment  appears  bitter  while  the  bilious  disposition  exists, 
and  insipid  in  those  diseases  in  which  the  mucous  elements 
prevail. 

* This  has  been  attempted,  though  with  indifferent  success,  by  Boerhaave, 
Haller,  and  Linnseus.  Acid,  sweet,  bitter,  acrid,  saltish,  alkaline,  vinous,  spirituous, 
aromatic,  and  acerb,  were  tbe  terms  employed  by  those  physicians  to  express 
the  general  characters  of  flavours. 


336 


OF  SEXSATIOXS. 


CXXVIII.  Of  the  sense  of  taste.  No  sense  is  so  much  akin 
to  that  of  the  touch,  or  resembles  it  more.  The  surface  of  the 
organ  of  taste  differs  from  the  common  integuments  only  in  this 
respect; — that  the  chorion,  the  mucous  body,  and  the  epidermis, 
which  envelop  the  fleshy  part  of  the  tongue,  are  softer,  thinner, 
and  receive  a greater  quantity  of  nerves  and  vessels,  and  are 
habitually  moistened  by  the  saliva  and  by  the  mucus,  secreted 
by  the  mucous  glands  contained  in  their  substance.  These  mu- 
cous cryptae,  and  the  nerves  of  the  cutaneous  covering  of  the 
tongue,  raise  the  very  thin  epidermis  which  covers  its  upper 
surface,  and  form  a number  of  papillag,  distinguished  by  their 
form  into  fungous.,  conical,  and  villous.  With  the  exception  of 
the  first  kind,  these  small  prominences  are  formed  by  the  ex- 
tremities of  nerves  surrounded  by  blood-vessels,  which  give  to 
these  papillae  the  power  of  becoming  turgid  and  prominent,  and 
of  being  affected  with  a kind  of  erection  when  we  eat  highly 
seasoned  food,  or  when  we  long  for  a savoury  dish.  The  fun- 
gous papillae  are  mostly  situated  at  the  remotest  part  of  the 
upper  surface  of  the  tongue,  towards  its  root,  where  it  forms  a 
part  of  the  isthmus  faucium.  The  pressure  with  which  they  arc 
affected  by  the  alimentary  bolus,  in  its  passage  from  the  mouth 
into  the  pharynx,  squeezes  out  the  mucus  which  lubricates  the 
edges  of  the  aperture,  and  serves  to  promote  its  passage:  these 
mucous  follicles  fulfil,  in  this  respect,  the  same  office  as  the 
amygdalae. 

The  upper  surface  of  the  tongue  is  the  seat  of  taste:  it  is  un- 
deniable, however,  that  the  lips,  the  gums,  the  membrane  lining 
the  arch  of  the  palate,  and  the  velum  palati,  may  be  affected  by 
the  impression  of  certain  flavours. 

It  is  observed  in  the  different  animals,  that  the  organ  of  taste 
is  more  perfect,  according  as  the  nerves  of  the  tongue  are  larger, 
its  skin  thinner  and  raoister,  its  tissue  more  flexible,  its  surface 
more  extensive,  its  motions  easier  and  more  varied.  Hence  the 
bone  in  the  tongue  of  birds,  by  diminishing  its  flexibility;  the 
osseous  scales  of  the  swan’s  tongue,  by  reducing  the  extent  of 
the  sentient  surface;  the  adhesion  of  the  tongue  to  the  jaws  in 
frogs,  in  the  salamander,  and  in  the  crocodile,  by  preventing 
freedom  of  motion,— render  in  these  animals,  the  sense  of  taste 
duller,  and  less  calculated  to  feel  the  impression  of  sapid  bodies, 


OF  SENSATIONS. 


337 


than  in  man,  and  the  other  mammiferous  animals.  Man  would 
probably  excel  all  the  other  animals  in  delicacy  of  taste,  if  he 
did  not,  at  an  early  period,  impair  its  sensibility  by  strong 
drinks,  and  by  the  use  of  spices,  and  of  all  the  luxuries  that  are 
daily  brought  to  our  tables.  The  quadrupeds,  whose  tongue  is 
covered  by  a rougher  skin,  discover  better  than  we  can,  by  the 
sense  of  taste,  poisonous  or  noxious  substances.  VVe  know  that 
in  the  variety  of  plants  which  cover  the  face  of  the  earth,  herbi- 
vorous animals  select  a certain  number  of  plants  suited  to  their 
nature,  and  uniformly  reject  those  which  would  be  injurious  to 
them. 

CXXIX.  Is  the  lingual  branch  of  the  fifth  pair  of  nerves 
alone  subservient  to  the  sense  of  taste?  Are  not  the  ninth  pair 
(almost  wholly  distributed  in  the  tissue  of  the  tongue),  and  the 
glosso-ph:iryngeal  branch  of  the  eighth,  likewise  sub-ervient  to 
this  function?  Most  anatomists,  since  Galen,  have  thought  that 
the  eighth  and  ninth  pair  supplied  the  tongue  with  its  nerves  of 
motion,  and  that  it  received  from  the  fifth  its  nerves  of  sensa- 
tion. Several  filaments,  however,  of  the  great  hypoglossal  nerve, 
may  be- traced  into  the  nervous  papillae  of  the  tongue.*  This 
nerve  is  larger  than  the  lingual,  and  is  more  exclusively  distri- 
buted to  this  organ  than  the  fifth  pair,  to  which  the  other  nerve 
belongs.  Hevermann  states,  that  he  knew  a case  in  which  the 
sense  of  taste  was  lost  from  the  division  of  the  nerve  of  the  ninth 
pair,  in  removing  a scirrhous  gland.  This  case,  however,  appears 
to  me  a very  suspicious  one.  The  patient  might  still  have  tasted, 
bymeans  of  the  lingual  nerve,  and  the  sense  would  only  have  been 
weakened.  The  division  of  one  of  the  nerves  of  the  ninth  pair 
could  render  insensible  only  that  half  of  the  tongue  to  which  it 
is  distributed,  the  other  half  would  continue  fully  to  possess  the 
faculty  of  taste. 

The  application  of  metals  to  the  different  nervous  filaments  dis- 
tributed to  the  tongue,  ought  to  inform  us  of  their  different  uses, 
if,  as  Humboldt  suspects,  the  galvanic  excitement  of  the  nerves 

* Especially  the  anterior  part  of  the  palatine  membrane.  The  naso-palatine 
nerve,  discovered  by  Scarpa,  after  arising-  from  the  ganglion  of  Mekel,  and 
going  tor  a pretty  considerable  distance  into  the  nasal  fossae,  terminates  in  that 
thick  and  rugous  portion  of  the  palatine  membrane  situated  behind  the  upper 
incisors,  and  with  which  the  tip  of  the  tongue  is  in  such  frequent  contact. 

2 U 


338 


OF  SENSATIONS. 


of  motion,  alone  produces  contractions.  To  ascertain  the  truth 
of  this  conjecture,  I placed  a plate  of  zinc  within  the  skull,  un- 
der the  trunk  of  the  nerve  of  the  fifth  pair,  in  a dog  that  had 
been  killed  a few  minutes  before,  and  that  still  retained  its 
warmth;  the  muscles  of  the  tongue,  under  which  a piece  of 
silver  was  placed,  quivered  very  slightly;  those  of  the  forehead 
and  temples  in  contact  with  the  same  metal,  experienced  very 
sensible  contractions,  whenever  a communication  was  made  by 
means  of  an  iron  rod.  This  experiment  showed,  that  the  lingual 
branch  of  this  nerve  was,  almost  solely,  subservient  to  the  sen- 
sation of  taste,  which  agrees  with  the  opinion  of  most  physiolo- 
gists, and  the  same  inference  may  be  drawn  from  the  anatomical 
knowledge  of  the  situation  of  this  nerve  which,  almost  entirely, 
terminates  in  the  papillce  of  the  membrane  of  the  tongue,  and 
sends  very  few  filaments  to  the  muscles  of  that  organ.  But  though 
the  galvanic  irritation  applied  to  the  hypoglossal  nerve  affected 
the  whole  tongue,  in  a convulsive  manner,  I did  not  think  myself 
justified  to  infer,  that  this  nerve  was  solely  destined  to  perform 
its  motions;  as  this  nervous  trunk  might,  in  this  part  of  the 
body,  as  it  does  in  others,  contain  filaments  both  of  sensation 
and  motion. 

The  tongue,  though  an  azygous  organ,  is  formed  of  parts 
completely  symmetrical;  there  are,  on  each  side,  four  muscles 
(stylo^  hyo^  genio^glosso  and  lingual');  three  nerves  (lingual^ 
glosso-pharyngeal,  and  hypoglossal);  a ranine  artery  and  vein; 
and  a set  of  lymphatic  vessels  precisely  alike.  All  these  parts, 
by  their  union,  form  a fleshy  body  of  a close  texture  and  Hot 
easily  unravelled,  similar  to  that  of  the  ventricles  of  the  heart, 
endowed  with  a considerable  degree  of  mobility,  in  consequence 
of  the  numerous  vessels  and  nerves  entering  into  its  substance. 
If  we  compare  their  number  and  size  with  the  small  bulk  of  the 
organ,  it  will  be  readily  understood,  that,  as  no  part  of  the  body 
can  execute  more  frequent,  more  extensive,  and  more  varied 
motions,  so  no  one  receives  more  vessels  and  nerves.  A middle 
line  separates  and  marks  the  limits  of  the  two  halves  of  the 
tongue,  which  anatomically  and  physiologically  considered,  ap- 
pears formed  of  two  distinct  organs  in  juxta-position. 

This  independence  of  the  two  parts  of  the  tongue  is  confirm- 
ed by  the  phenomena  of  disease;  in  hemiplegia,  the  side  of  the 


OF  SENSATIONS. 


339 


tongue  corresponding  to  the  half  of  the  body  that  is  paralyzed, 
loses,  likewise,  the  power  of  motion;  the  other  retains  its  mobi- 
lity, and  draws  the  tongue  towards  that  side.  In  carcinoma  of 
the  tongue,  pne  side  remains  unaffected  by  the  affection  which 
destroys  the  other  half;  lastly,  the  arteries  and  nerves  of  the  left 
side  rarely  anastomose  with  those  on  the  right;  injections  forced 
along  one  of  the  ranine  arteries,  fill  only  the  corresponding  half 
of  the  organ,  &c. 

CXXX.  Of  the  touch.  No  part  of  the  surface  of  our  body  is 
exposed  to  receive  the  touch  of  a foreign  body,  without  our 
being  speedily  informed  of  it.  If  the  organs  of  sight,  of  hearing, 
of  smell  and  of  taste,  occupy  only  limited  spaces,  touch  resides 
in  all  the  other  parts  and  effectually  watches  over  our  preserva- 
tion. The  touch,  distributed  over  the  whole  surface,  appears  to 
be  the  elementary  sense,  and  all  the  others  are  only  modifica- 
tions of  it,  accommodated  to  certain  properties  of  bodies.  All 
that  is  not  light,  sound,  smell,  or  flavour,  is  appreciated  by  the 
touch,  which  thus  instructs  us  in  the  greater  part  of  the  quali- 
ties of  bodies  which  it  concerns  us  to  know,  as  their  tempera- 
ture, their  consistence,  their  state  of  dryness,  or  humidity,  their 
figure,  their  size,  their  distance,  &c.  It  corrects  the  errors  of 
the  sight  and  of  all  the  other  senses,  of  which  it  may  justly  be 
called  the  regulator,  and  it  furnishes  us  with  the  most  exact  and 
distinct  ideas. 

The  touch,  of  which  some  authors  have  sought  to  consecrate 
the  excellence,  by  giving  it  the  name  of  the  geometrical  sense, 
is  not,  however,  safe  from  all  mistake.  Whilst  it  is  employed 
on  the  geometrical  properties,  derived  from  space,  and  that  it 
appreciates  the  length,  the  breadth,  the  thickness,  the  form  of 
bodies,  it  transmits  to  the  intellect,  rigorous  and  mathematical 
results;  but  the  ideas  we  acquire  by  its  means  on  the  tempera- 
ture of  bodies,  are  far  from  being  equally  precise.  For,  if  you 
have  just  touched  ice,  another  body  colder  than  yours,  will  ap- 
pear warm.  It  is  for  this  reason,  that  subterraneous  places  ap- 
pear warm  to  us  during  winter.  They  have  kept  their  tempera- 
ture whilst  all  things  else  have  changed  theirs;  and  as  we  judge 
of  the  heat  of  an  object  by  its  relation  not  only  to  our  own,  but 
also  to  that  of  other  bodies  and  of  the  air  about  us,  we  find  the 


340 


OF  SENSATIONS. 


same  places  warm  wbich  had  appeared  cold  to  us  in  the  middle 
of  summer. 

The  densest  bodies  being  the  best  conductors  of  heat,*  mar- 
ble, metals,  &c.  appear  colder  to  us  than  they  really  are,  because 
they  carry  it  olF  so  rapidly.  Marble  and  metals,  when  polished, 
appear  still  colder,  because,  as  they  touch  the  skin  in  many 
more  points  at  once,  they  effect  this  abstraction  more  effec- 
tually. Every  one  knows  the  experiment  of  placing  a little  ball 
between  the  two  fingers  crossed,  and  producing  the  sensation 
of  two  different  balls. 

CXXXI.  Of  the  integuments.  The  general  covering  of  the 
whole  body  is  the  organ  of  touch,  which  resides  in  the  skin  pro- 
perly so  called.  The  cellular  tissue  which  connects  together  all 
our  parts,  forms  over  the  whole  body,  a layer  varying  in  thick- 
ness, which  covers  it  in  every  part;  it  is  called  panniculus  adi- 
posus.  As  it  approaches  the  surface,  its  laminae  are  more  con- 
densed, are  in  more  immediate  contact  with  each  other,  and  are 
no  longer  separated  by  adeps.  It  is  by  the  closer  juxta-position 
of  the  laminae  of  the  cellular  tissue,  that  the  skin  or  dermis  is 
formed,  a dense  and  elastic  membrane,  into  which  numerous 
vessels,  of  all  kinds,  are  distributed,  and  into  which  so  great  a 
quantity  of  nerves  terminate,  that  the  ancients  did  not  hesitate 
to  consider  the  skin  as  purely  nervous. 

In  certain  parts  of  the  body,  a very  thin  muscular  plane  sepa- 
rates the  skin  from  the  panniculus  adiposus.  This  kind  of  pan- 
niculus carnosus  envelops,  almost  entirely,  the  body  of  some 
animals;  its  contractions  wrinkle  their  skin  covered  with  hairs, 
these  rise,  vibrate,  and  thus  are  cleared  of  the  dust  and  dirt 
which  may  have  gathered  on  them.  It  is  by  means  of  a cuta- 
neous muscle,  of  very  complex  structure,  that  the  hedge  hog  is 

* Woolly  substances,  8cc.  all  felts,  of  which  the  crossing-  hairs  confine,  in 
some  sort,  a great  quantity  of  air,  a fluid  which,  from  its  gaseous  state,  is  a 
very  bad  conductor  of  heat,  retain  heat  well;  and,  of  equal  thickness,  a stuff  of 
fine  wool,  of  which  the  hairs  are  more  separated,  the  tissue  softer,  will  be 
warmer  than  a stuff  of  coarse  wool,  of  which  the  threads,  too  close,  form  a 
dense  body,  through  which  cold,  as  well  as  heat,  will  pass  with  ease.  It  is  by 
thus  confining  a certain  mass  of  air,  that  snow  keeps  the  soil  it  covers  in  a 
mild  temperature,  and  preserves  plants  from  the  injury  of  e.\cessive  cold:  a 
physical  truth  which  is  found  figuratively  expressed  in  the  -words  of  the 
Psalmist,  “ Et  dedit  illi  nivem  tanquam  vesthnentum.  ” 


OF  SENSATIONS. 


341 

enabled  to  coll  himself  up,  and  to  present  to  his  enemy  a surface 
studded  with  sharp  points:  only  a few  scattered  rudiments  of  an 
analogous  structure,  are  to  be  met  with  in  the  human  body;  the 
occipito-frontalis,  the  corrugator  supercilii,  several  muscles  of 
the  face,  the  platysma  myoides,  the  palmaris  cutaneus,  may  be 
considered  as  forming  part  of  this  muscle.  We  may  even  in- 
clude the  cremaster,  whose  expanded  fibres,  surrounded  by  the 
dartos,  have  misled  some  anatomists  to  such  a degree,  that  they 
have  admitted  the  existence  of  a muscular  texture  in  the  latter. 
These  fibres  of  the  cremaster,  produce  distinct  motions  in  the 
skin  of  the  scrotum,  wrinkle  it  in  a transverse  direction,  and,  at 
the  same  time,  bring  up  the  testicles.  The  platysma  myoides 
acts,  likewise,  on  the  skin  of  the  neck;  lastly,  the  occipito-fron- 
talis, in  some  men,  performs  so  distinct  a motion  of  the  hairy 
scalp,  as  to  throw  off  a hat,  a cap,  or  any  other  covering  that 
may  be  on  the  head.  One  may  compare  to  the  panniculus  car- 
nosus,  the  muscular  coat  of  the  digestive  tube,  situated,  through- 
out its  whole  length,  below  the  mucous  membrane,  which  is 
merely  a prolongation  of  the  skin  modified  and  softened.. 

But  if,  in  man,  the  subcutaneous  muscle,  from  its  imperfect 
state,  answers  purposes  only  of  secondary  importance,  the  layer 
of  cellular  adipose  substance,  extended  under  the  skin,  gives  to 
the  latter  its  tension,  its  whiteness,  its  polish,  its  suppleness,  fa- 
vours its  applying  itself  to  tangible  objects  and  thus  renders  the 
touch  more  delicate.  Too  hard  or  wrinkled  a skin  would  have 
applied  itself  in  a very  incomplete  manner,  to  bodies  of  a small 
size,  and  would  not  readily  have  accommodated  itself  to  the 
small  irregularities  of  those  of  inconsiderable  bulk.  Hence  the 
pulp  of  the  fingers,  which  is  the  seat  of  a more  delicate  touch, 
is  furnished  with  a kind  of  adipose  cushion  supported  by  the 
nails,  ready  to  be  applied  to  polished  surfaces,  and  to  discover 
their  slightest  asperities.  I have  observed  the  sense  of  touch  to 
be  very  imperfect  in  men  wasted  by  marasmus,  and  whose  hard, 
dry,  and  wrinkled  skin  adheres,  in  certain  situations,  to  the 
subjacent  parts. 

The  chemical  analysis  of  the  cutaneous  tissue  shows,  that  it 
does  not  exactly  resemble  that  of  the  cellular  and  membranous 
tissue;  it  is  gelatino-fibrous,  and,  with  regard  to  its  structure 
and  to  its  share  of  contractility,  it  occupies  a medium  between 


342 


OF  SENSATIONS. 


the  cellular  tissues  and  the  muscular  flesh.  There  arise,  from 
the  surface  of  the  skin,  innumerable  small  papillae,  fungous, 
conical,  pointed,  obtuse  and  variously  shaped,  in  the  different 
parts  of  the  body.  These  papillae  are  merely  the  pulpous  extre- 
mities of  the  nerves  which  terminate  into  them,  and  around  which 
there  are  distributed  vascular  tissues  of  the  utmost  minuteness. 
The  papillae  of  the  skin,  which  are  more  distinct  in  the  fingers 
and  lips  than  elsewhere,  swell,  when  irritated,  elevate,  in  a man- 
ner, the  epidermis,  and  this  kind  of  erection,  which  is  useful 
when  we  wish  to  touch  a substance  with  great  precision,  may 
be  excited  by  friction  or  by  moderate  heat. 

The  nervous  or  sentient  surface  of  the  skin  is  covered  with  a 
mucous  coating,  colourless  in  Europeans,  of  dark  colour,  from 
the  effects  of  light,  among  the  natives  of  southern  climates;  of  a 
gelatinous  nature,  destined  to  maintain  the  papillae  in  that  state 
of  moisture  and  softness  favourable  to  the  touch.  This  mucila- 
ginous layer,  known  under  the  name  of  rete  mucosum  of  Mal- 
pighi, seems  to  contain  the  principle  which  causes  the  variety  of 
colour  in  the  skin  of  different  nations,  as  will  be  observed  in 
speaking  of  the  varieties  of  the  human  species. 

The  reticular  state  of  the  rete  mucosum  may  be  explained  in 
two  ways;  a thin  and  gelatinous  layer,  extended  on  the  papillar 
surface  of  the  skin,  is  perforated  at  each  nervous  papilla:  and  if 
it  were  possible  to  coagulate  or  to  detach  this  coating,  we  should 
have  a real  sieve,  or  reticulated  mesh  work,  with  a perforation 
at  every  point,  corresponding  to  a cutaneous  papilla.  The  san- 
guineous and  lymphatic  capillaries  which  surround  the  nervous 
papillae,  form,  besides,  by  their  connexions,  a net-work,  the 
meshes  of  which  are  very  minute,  and  adhere  to  the  epidermis 
by  a multitude  of  small  vascular  filaments  that  insinuate  them- 
selves between  the  scales  of  this  last  envelope. 

The  skin  would  be  unable  to  perform  its  functions,  if  an  outer, 
thin,  and  transparent  membrane,  the  epidermis^  did  not  prevent 
it  from  being  over  dried.  This  superficial  covering  is  quite  in- 
sensible, no  nerves  and  no  vessels  of  any  kind  are  found  in  it, 
and  even  in  the  present  state  of  the  science,  we  do  not  under- 
stand how  it  is  formed,  how  it  repairs  and  reproduces  itself 
when  destroyed.  The  most  minute  researches  on  its  structure, 
merely  show  the  existence  of  an  infinite  number  of  lamellae, 


OF  SENSATIONS. 


S43 

lying  over  each  other,  and  overlapping  each  other,  like  the  tiles 
of  a roof.  This  embrkation  of  the  epidermoid  lamellae,  is  very 
obvious  in  fishes  and  reptiles,  the  scaly  skin  of  which  is  merely 
an  epidermis,  whose  parts  are  much  more  coarsely  shaped. 

It  was  observed  (XLII.),  in  the  account  of  absorption,  how 
much  friction  facilitates  the  absorption  of  substances  applied  to 
the  surface  of  the  skin,  by  raising  the  scales  of  the  epidermis,  so 
as  to  expose  the  orifices  of  the  absorbents,  whose  activity,  it  in 
other  respects,  increases. 

Haller  conceives  that  the  epidermis  is  formed  by  the  drying 
up  of  the  outer  layers  of  the  rete  mucosum.  Morgagni  thinks  it 
is  formed  by  the  induration  of  the  skin  in  consequence  of  the 
pressure  of  the  atmosphere.  In  objection  to  these  hypotheses, 
one  may  enquire,  how  it  happens,  that  by  the  time  the  foetus, 
immersed  in  the  liquor  amnii,  has  attained  its  third  month,  it 
is  covered  with  such  an  envelope.  Pressure  renders  the  skin 
hard  and  callous,  increases  considerably  its  thickness,  as  we  see 
in  the  soles  of  the  feet  and  in  the  palms  of  the  hands  of  persons 
engaged  in  laborious  employments.  The  epidermis  reproduces 
itself  with  an  incredible  rapidity,  after  falling  off  in  scales,  after 
erysipelas  or  herpetic  eruptions;  or,  when  removed  in  large 
flakes,  by  blistering,  it  is  renewed  in  the  course  of  a very  few 
days.  The  cuticle,  together  with  the  hairs  and  the  nails,  which 
may  be  considered  as  productions  of  the  same  substance,  are 
the  only  parts,  in  man,  that  are  capable  of  reproducing  them- 
selves. The  hairs  and  the  horns  of  quadrupeds,  the  feathers  of 
birds,  the  calcareous  matter  of  the  lobster  and  of  several  mol- 
lusca,  the  shell  of  the  turtle,  the  solid  sheaths  of  a number  of 
insects,  possess,  as  well  as  the  epidermis,  this  singular  property. 
In  other  respects,  the  chemical  structure  of  all  these  parts  is 
the  same;  they  all  contain  a considerable  proportion  of  phos- 
phate of  lime,  withstand  decomposition,  and  give  out  a consi- 
derable quantity  of  ammonia,  on  being  exposed  to  heat.  The 
use  of  the  epidermis  is  to  cover  the  nervous  papillae,  in  which 
the  faculty  of  the  touch  essentially  resides,  to  moderate  the  too 
vivid  impression  that  would  have  been  produced  by  an  imme- 
diate contact,  and  to  prevent  the  air  from  drying  the  skin  or 
from  impairing  its  sensibility. 

This  desiccation  of  the  cutaneous  tissue  is  further  prevented, 


344 


OF  SENSATIONS. 


and  its  suppleness  maintained  by  an  oily  substance,  which  exudes 
through  its  pores,  and  is  apparently  secreted  by  the  cutaneous 
exhalants.  This  unctuous  liniment  should  not  be  mistaken  for 
that  which  is  furnished  by  the  sebaceous  glands,  in  certain 
situations,  as  around  the  nostrils,  in  the  hollow  of  the  arm-pits, 
and  in  the  groins.  This  adipose  substance,  with  which  the  skin 
is  anointed,  is  abundant  and  fetid  in  some  persons,  especially  in 
those  of  a bilious  temperament,  with  red  hair.  It  is,  likewise, 
more  copious  in  the  African  negroes,  as  if  nature  had  been 
anxious  to  guard  against  the  too  rapid  desiccation,  by  the 
burning  atmosphere  of  tropical  climates.  This  use  of  the  oil 
of  the  skin,  is,  likewise,  answered  by  the  tallow,  the  fat,  and 
the  disgusting  substances  with  which  the  Caffres  and  the  Hot- 
tentots anoint  their  body,  in  the  manner  described  under  the 
name  of  tatooing,  by  the  travellers*  who  have  penetrated  into 
the  interior  of  the  burning  regions  of  Africa. 

The  ancients  had  a somewhat  similar  practice,  and  the  anoint- 
ing with  oil,  so  frequently  used  in  ancient  Rome,  answered  the 
same  purpose  of  softening  the  skin,  of  preventing  its  becoming 
dry,  or  chapped. | The  pomatums  employed  at  the  present  day 
at  the  toilet,  possess  the  same  advantages.  The  continual  tran- 
sudation of  this  animal  oil  renders  it  necessary,  occasionally,  to 
clean  the  skin  by  bathing;  the  water  removes  the  dust  and  the 
other  impurities  which  may  be  attached  to  its  surface  b}’  the 
fluid  which  lubricates  it.  It  is  this  humour  which  soils  our 
linen  and  obliges  us  so  frequently  to  renew  that  in  immediate 
contact  with  the  skin,  and  which  makes  the  water  collect  in 
drops  when  we  come  out  of  the  bath,  &c. 

Though  the  parts  in  w'hich  there  is  found  the  greatest  quan- 
tity of  subcutaneous  fat,  are  not  always  the  most  oily,  and  though 
one  cannot  consider  this  secretion  as  a mere  filtration  of  this 
adeps  through  the  tissue  of  the  skin,  corpulence  has,  however, 
a manifest  influence  on  its  quantity.  I know  several  very  cor- 

* Among' others  Kolben,  Description  du  Cap  de  Bonne-Esp6rance;  Sparmann, 
Voyage  au  Cap  de  Bonne-Esperaace,  et  c/iez  les  Hottentots-  Vaillant,  Voyage  dam 
Vinterieur  de  L' Afrique. 

-j-The  reply  of  the  old  soldier  is  well  known,  who,  on  being  asked  by 
Augustus,  how  he  came  to  live  so  long,  said,  he  owed  his  long  life  to  the  use 
of  wine  inwardly,  and  to  that  of  oil  outwardly;  intus  vino,  estus  oleo. 


OF  SENSATIONS. 


345 


pulent  persons  in  whom  it  appears  to  be  evacuated  by  perspira- 
tion, on  their  being  heated  by  the  slightest  exertion.  They  all 
grease  their  linen  in  less  than  twenty-four  hours.  An  excess  of 
the  oily  matter  of  perspiration  is  injurious,  by  preventing  the 
evacuation  of  the  perspiration  and  its  solution  in  the  atmos- 
phere. 

We  all  know  how,  after  the  epidermis  has  been  removed,  the 
slightest  contact  is  painful:  that  of  the  air  is  sufficient  to  bring  on 
a painful  inflammation  of  the  skin  exposed  by  the  application  of 
a blister.  The  epidermis,  as  was  likewise  naentioned  in  speaking 
of  the  absorption,  placed  on  the  limits  of.  the  animal  economy, 
and  in  a manner  inorganic,  serves  to  prevent  heterogeneous  sub- 
stances from  being  too  readily  admitted  into  the  body,  and,  at 
the  same  time,  it  lessens  the  too  vivid  action  of  external  objects 
on  our  organs.  All  organized  and  living  bodies  are  furnished 
with  this  covering,  and,  in  all,  in  the  seed  of  a plant,  in  its  stem, 
and  on  the  surface  of  the  body,  in  man  and  animals,  it  bears  to 
the  skin  the  greatest  analogy  of  function  and  nature.  Incor- 
ruptibility is,  in  a manner,  its  essence,  and  is  its  peculiar  charac- 
ter; and  in  tombs  which  contain  merely  the  dust  of  the  skeleton, 
it  is  not  uncommon  to  find  whole  and  in  a state  to  be  readily 
distinguished,  the  thickened  epidermis  that  forms  the  sole  of 
the  foot  and  especially  the  heel.  However,  this  incorruptibility 
is  possessed,  as  well  as  others  of  the  qualities  of  the  skin,  by 
the  nails  and  the  hairs,  which  may  be  considered  as  its  ap- 
pendages. 

CXXXII.  Of  the  nails.  The  nails  are,  in  fact,  only  a part  of 
the  epidermis:  they  are  continuous  with  it,  and  after  death,  fall 
off  along  with  it.  They  are  thicker  and  harder:  like  it  they  are 
inorganic  and  lamellated;  they  grow  rapidly  from  their  root  to- 
wards their  free  extremity;  they  reproduce  themselves  rapidly 
and  acquire  several  inches  in  length,  when  the  part  beyond  the 
ends  of  the  fingers  and  toes  has  not  been  removed;  as  is  the 
case  with  the  Indian  fakirs.  In  this  state  of  development,  they 
bend  over  the  tips  of  the  fingers  and  toes,  and  impair  the  sense 
of  touch,  whose  free  enjoyment  is  preferable  to  any  advantages 
which  savages  can  derive  from  their  long  and  crooked  nails,  in 
defending  themselves,  or  in  attacking  animals,  or  tearing  to 

2 X 


346 


Of  SENSATIONS, 


pieces  those  which  they  have  killed  in  hunting.  The  nails  are 
quite  insensible;  and  the  reason  that  so  much  pain  is  felt,  when 
the  nails  run  into  the  flesh,  and  that  the  operation  of  tearing 
them  out,  which  is  sometimes  necessary,  is  so  painful,  is,  that 
the  nerves,  over  which  the  nail  grows,  are  more  or  less  in- 
jured when  it  grows  in  a wrong  direction.  The  pain  from  the 
growing  of  the  nails  into  the  quick,  is  no  proof  of  their  being 
sentient,  any  more  than  the  growth  of  corns  proves  the  sensi- 
bility of  the  epidermis,  of  which  they  are  but  thickened  parts, 
become  hard  and  callous  by  pressure,  and  which,  confined  in 
tight  shoes,  press  painfully  on  the  nerves  below.  The  nail 
itself  may  acquire  a considerable  degree  of  thickness;  I have 
seen  that  of  the  great  toe  nearly  half  an  inch  thick.  The  use  of 
the  nails  is  to  support  the  tips  of  the  fingers,  when  they  are 
applied  to  unyielding  substances;  they  likewise  concur  in  im- 
proving the  mechanism  of  the  touch*. 

CXXXIII.  Of  the  hair  on  the  head  and  on  other  parts  of 
the  body.  These  parts  are  treated  of,  in  the  present  instance, 
only  in  consequence  of  their  connexion  with  the  epidermis;  as, 
far  from  improving  the  touch,  they  interfere  with  it,  or  at  least 
render  it  less  delicate. 

The  skin,  in  man,  is  more  bare  than  that  of  other  animals; 
it  is,  likewise,  least  covered  with  insensible  parts  that  might 
blunt  the  sense  of  touch.  In  almost  all  mammiferous  animals, 
the  whole  body  is  covered  with  hair;  only  a small  part  of  the 
human  body  has  any  hair  on  it,  and  that  in  too  small  a quantity, 
and  of  too  delicate  a texture,  to  interfere  with  the  touch.  Some 
men,  however,  have  a very  hairy  skin;  and  I have  seen  several 

* The  toe  nails  are  favourable  to  the  laying  the  foot  to  the  surface  on  which 
the  body  is  supported;  they  likewise  improve  the  sense  of  touch  in  this  part. 
The  use  of  the  feet  is  not  merely  to  support  the  weight  of  the  body,  they  are 
also  intended  to  guide  us  in  feeling  for  the  plane  on  which  we  are  to  rest  them, 
to  enable  us  to  judge  of  the  solidity,  of  the  temperature,  and  of  the  inequalities 
of  the  ground  on  which  we  tread.  They,  therefore,  required  rather  a delicate 
sense  of  touch.  The  division  of  the  fore  part  of  the  foot,  into  several  distinct 
and  separate  parts,  serves  to  enable  us  to  stand  more  firmly,  and  facilitates  the 
action  of  walking.  I have  seen  several  soldiers  who  lost,  from  severe  cold, 
the  extremities  of  their  feet,  in  crossing  the  Alps  which  separate  France  from 
Italy.  Those  who  had  lost  only  their  toes,  did  not  walk  so  steadily,  and  fre- 
quently fell,  in  treading  on  uneven  ground.  Those  who  had  lost  one  half  of 
their  feet,  were  obliged  to  use  crutches. 


OF  SENSATIONS. 


347 

who,  when  naked,  looked  as  if  covered  over  with  the  skin  of  an 
animal,  so  great  was  the  quantity  of  hair  over  the  whole  body, 
of  which  no  part  was  bare,  but  a small  proportion  of  the  face,  the 
palms  of  the  hands  and  the  soles  of  the  feet.  This  extraordinary- 
growth  of  hair,  is  in  general,  a sure  sign  of  vigour  and  strength. 
In  childhood,  there  is  no  hair  except  on  the  head,  the  rest  of 
the  body  is  covered  with  down.  Women  have  no  beard,  and 
there  is  in  them,  a smaller  quantity  of  hair  in  the  arm  pits  and 
on  the  parts  of  generation,  and  scarcely  any  on  the  limbs  and 
trunk.  But  as  though  the  matter  which  should  provide  for  the 
growth  of  the  hair,  were  wholly  applied  to  the  hairy  scalp,  it  is 
observed,  that  their  hair  is  longer  and  in  greater  quantity. 

The  colour  of  the  hair  varies  from  white  to  jet  black;  and,  as 
will  be  mentioned,  in  speaking  of  the  temperaments  and  of  the 
varieties  of  the  human  species,  this  difference  of  colour  is  a test 
by  which  judge  of  those  varieties.  The  colour  of  the  hairs 
enables  us  to  judge  of  their  thickness:  Withof,  who,  with  a 
truly  German  patience,  was  at  the  pains  to  count  how  many 
hairs  were  contained  in  the  space  of  a square  inch,  states,  in 
his  dissertation  on  the  human  hair,  that  there  are  five  hundred 
and  seventy-two  black  hairs,  six  hundred  and  eight  chesnut, 
and  seven  hundred  and  ninety  light  coloured;  so  that  the  diame- 
ter of  a hair,  which  is  between  the  three  and  seven  hundredth 
part  of  an  inch,  is  least  in  light  hair,  and  these  are  finer  the 
lighter  their  shade.  It  is,  likewise,  observed,  that  men  of  a 
bilious  constitution,  with  dark  hair  and  inhabiting  warm  cli- 
mates, have  more  hair  in  other  parts  of  the  body,  and  that  it  is 
coarser  and  more  greasy. 

In  whatever  part  of  the  body  hairs  may  grow,  they  are,  every 
where,  of  the  same  structure,  they  all  arise  from  a vesicular 
bulb  in  the  adipose  cellulur  tissue;  from  this  bulb  containing  a 
gelatinous  lymph,  on  which  the  hair  seems  to  be  nourished, 
the  latter,  at  first  divided  into  two  or  three  filaments  which 
constitute  a kind  of  root,  comes  out  in  a single  trunk,  passes 
through  the  skin  and  epidermis,  receiving  from  the  latter  a 
sheath  that  covers  it  to  its  extremity,  which  terminates  in  a 
point. 

A hair  may,  therefore,  be  considered  as  an  epidermoid  tube 
filled  with  a peculiar  kind  of  marrow.  This  spungy  stem,  which 


348 


OF  SENSATIOXS. 


forms  the  centre  of  a hair,  is  a more  essential  part  of  it,  than  the 
sheath  supplied  by  the  epidermis.  Along  this  spungy  and  cellu- 
lar filament,  the  animal  oil  of  the  hair  and  the  juices  on  which 
it  is  repaired  flow.  Though  we  see,  in  some  animals,  vascular 
branches  and  very  small  nervous  filaments  directed  towards  the 
root  of  certain  kinds  of  hair,  and  lost  in  it,  as  is  the  case  with 
the  long  and  stiff  whiskers  of  some  of  the  quadrupeds,  it  is  im- 
possible to  say,  whether  in  man,  the  hair  or  its  bulbs  receives 
vessels  and  nerves.  Is  the  human  hair  nourished  by  the  imbibition 
of  the  gelatinous  fluid  contained  in  its  bulb,  or  is  it  nourished 
on  the  fat  in  which  the  latter  is  embedded?  Are  vessels  distri- 
buted along  their  axis,  from  the  root  to  the  extremity?  In  favour 
of  this  opinion,  it  was  usual  to  mention  the  bleeding  from  the 
hair  when  cut,  in  the  disease  called  plica  polonica.  But  this  dis- 
ease, lately  observed  in  Poland,  by  the  French  physicians,  ap- 
peared to  them  a mere  entangling  of  hair,  in  consequence  of 
the  filth  of  the  Poles  and  of  their  habit  of  keeping  their  head 
constantly  covered  with  a woollen  cap.  The  hairy  scalp  re- 
mains perfectly  sound  beneath  the  entangled  hair,  and  the  only 
way  to  cure  the  complaint  is  to  cut  off  the  hair.  Fourcroy* 
thinks  that  each  hair  has  several  short  branches  that  stand  off 
from  it,  which,  according  to  the  explanation  given  by  Monge, 
favour  the  matting  of  the  hairs  that  are  to  be  converted  into 
tissues,  by  the  process  called  felting. 

CXXXIV.  Among  the  most  remarkable  qualities  of  the  hair 
one  may  take  notice  of  the  manner  which  it  is  affected  by 
damp  air,  which,  by  relaxing  its  substance,  increases  its  length. 
It  is  on  that  account,  that  hairs  are  used  for  the  construction  of 
the  best  hygrometers.  Nor  must  we  omit  either  the  readiness 
with  which  they  grow  and  are  reproduced,  even  after  being 
plucked  out  by  the  roots,  as  I have  often  seen  after  the  cure  of 
tinea  by  a painful  method:  nor  their  insulating  property,  with 
respect  to  the  electric  fluid,  of  which  they  are  very  bad  con- 
ductors; a remarkable  property,  viewed  with  reference  to  the 
conjectured  nature  of  the  nervous  fluid. 

The  hairs  possess  no  power  of  spontaneous  motion  by  which 


'^Systime  ties  connoissances  chimiques,  tome  IX.  page  263. 


OF  SENSATIONS. 


349 


they  can  rise  on  the  head,  when  the  soul  shudders  with  horror 
or  fear:  but  they  do  bristle  at  those  times,  by  ihe  contraction 
of  the  occipito-frontalis,  which,  intimately  adhering  to  the  hairy 
scalp,  carries  it  along  in  all  its  motions. 

They  appear  totally  without  sensibility:  nevertheless,  the  pas- 
sions have  over  them  such  influence,  that  the  heads  of  young 
people  have  turned  white  the  night  before  execution.  The  Re- 
volution, which  produced  in  abundance  the  extremes  of  hu- 
man suflfering,  furnished  many  authentic  instances  of  persons 
that  grew  hoary,  in  the  space  of  a few  days.  In  this  premature 
hoariness,  is  the  hair  dried  up,  as  in  old  people,  when  it  seems 
to  die  for  want  of  moisture  and  its  natural  juices? 

The  following  fact  seems  to  show,  that  they  are  the  excre- 
tory organ  of  some  principle,  the  retention  of  which  might  be 
of  very  injurious  consequence.  A chartreux  who,  every  month, 
had  his  head  shaved,  according  to  the  rule  of  his  order,  quitting 
it  at  its  destruction,  went  into  the  army,  and  let  his  hair  grow. 
After  a few  months  he  was  attacked  with  excruciating  head- 
aches, which  nothing  relieved.  At  last,  some  one  advised  him 
to  resume  his  old  habit,  and  to  have  his  head  frequently  shaved; 
the  head-aches  went  off",  and  never  returned. 

We  know,  says  Grimaud*,  that  there  are  nervous  head-aches, 
which  give  way  to  frequent  cropping  the  hair:  when  it  is  kept 
close  cut,  the  more  active  growth  that  takes  place  sets  in  motion 
stagnating  juices.  A friend  of  Valsalva,  as  Morgagni  t relates, 
dispelled  a maniacal  affection,  by  having  the  head  of  the  patient 
shaved;  Casimir  Medicus  cured  obstinate  gonorrhosa,  by  the 
frequent  shaving  of  the  parts  of  generation. 

The  hairs  partake  of  the  inalterability,  the  almost  indestructi- 
bility of  the  epidermis.  Like  it  they  burn  with  a fizzing,  and 
give  out  in  abundance  a fetid  ammoniacal  oil.  The  ashes  that 
remain  from  burning  them,  contain  much  phosphate  of  lime. 
The  horns  of  mammifer®,  the  feathers  of  birds,  give  out  the 
same  smell  in  burning,  and  yield  the  same  products  as  the  hair 
on  the  head  and  other  parts;  which  has  led  to  the  saying,  that 
these  last  were  a sort  of  horny  substance  drawn  out  like  wire. 
Acids,  but  especially  alkalies,  dissolve  them:  accordingly,  all 

* Second  Memoir  on  Nutrition,  p.  49.  f De  Sedibus  et  Causis,  epLst.  8,  No.  T. 


350 


OF  SENSATIONS. 


nations  that  cut  the  beard,  first  soften  it  by  rubbing  it  with  alka- 
line and  soapy  solutions. 

Is  the  use  of  the  hair  to  evacuate  the  superabundant  nutri- 
tious matter?  The  epoch  of  puberty  and  of  the  termination  of 
growth,  is  that  in  which  it  first  springs  in  many  parts  of  the 
body,  which  were  before  without  it.  They  are,  at  the  same  time, 
the  emunctory  by  which  nature  gets  rid  of  the  phosphate  of 
lime,  which  is  the  residue  of  the  work  of  nutrition.  The  hairs 
of  quadrupeds,  whose  urine  abounds  less  in  phosphoric  salts 
than  that  of  man,  seem  especially  to  fulfil  this  destination.  The 
hairs  have  some  analogy  with  the  fat,  which  has  not  yet  been 
ascertained.  They  are  often  found  accidentally  developed  in  the 
fatty  tumours  known  under  the  name  of  steatomas.  Finally, 
they  have  uses  relative  to  the  parts  on  which  they  grow. 

CXXXV.  The  faculty  of  taking  cognizance  of  tangible  quali- 
ties, belongs  to  all  parts  of  the  cutaneous  organ.  We  have  only 
to  apply  a substance  to  any  part  of  the  surface  of  our  body,  to 
acquire  the  idea  of  its  temperature,  of  its  dryness  or  moisture, 
of  its  weight,  its  consistence,  and  even  its  particular  figure.  But 
no  part  is  better  fitted  to  acquire  exact  notions,  on  all  these 
properties,  than  the  hand^  which  has  ever  been  considered  as  the 
especial  organ  of  touch.  The  great  number  of  bones  that  form 
its  structure,  make  it  susceptible  of  very  various  motion,  by 
which  it  changes  its  form,  adapts  itself  to  the  inequalities  of  the 
surfaces  of  bodies,  and  exactly  embraces  them:  this  apt  con- 
formation is  particularly  manifest  at  the  extremities  of  the  fin- 
gers. Their  anterior  part,  which  is  endued  with  the  most  deli- 
cate feeling,  receives  from  the  median  and  cubital  nerves, 
branches  of  some  size,  which  end  in  rounded  extremities,  close, 
and  surrounded  with  a cellular  tissue.  The  part  of  the  fingers 
which  is  called  their  pulp,  is  supported  by  the  nails;  vessels  in 
great  number  are  spread  through  this  nervo-cellular  tissue,  and 
moisten  it  with  abundant  juices,  that  keep  up  its  suppleness. 
When  perspiration  is  increased,  it  breaks  out  in  small  drops 
over  this  extremity  of  the  fingers,  along  the  hollow  of  the  con- 
centric lines  with  which  the  epidermis  is  furrowed. 

It  has  been  attempted  to  explain  the  pleasure  we  feel  in 
touching  rounded  and  smooth  surfaces,  by  showing  that  the  re- 
ciprocal configuration  of  the  hand  and  of  the  body  to  which  it 


OF  SENSATIONS. 


351 

is  applied,  is  such,  that  they  touch  in  the  greatest  number  of 
points  possible.  The  delicacy  of  the  touch  is  kept  up  by  the 
fineness  of  the  epidermis:  it  increases  by  education,  which  has 
more  power  over  this  sense  than  over  any  of  the  others.  It  is 
known  with  what  eagerness  a child,  allowed  the  free  use  of  his 
limbs,  stretches  his  little  hands  to  all  the  objects  within  his 
reach;  what  pleasure  he  seems  to  take  in  touching  them  in  all 
their  parts,  and  running  over  all  their  surfaces.  Blind  men  have 
been  known  to  distinguish  by  touch  the  different  colours,  and 
even  their  different  shades.  As  the  difference  of  colour  depends 
on  the  disposition,  the  arrangement,  and  number  of  the  little 
inequalities  which  roughen  the  surface  of  bodies  that  appear  the 
most  polished,  and  fit  them  to  reflect  such  or  such  a ray  of  light, 
absorbing  all  the  others,  one  does  not  refuse  to  believe  facts  of 
this  kind,  related  by  Boyle  and  other  natural  philosophers. 

Some  parts  appear  endowed  with  a peculiar  touch;  such  are 
the  lips,  whose  tissue  swells,  and  spreads  out  under  a volup- 
tuous contact;  a vital  turgescence,  explicable  without  the  sup- 
position of  a spungy  tissue  in  their  structure:- — such  are  those 
organs  which  Buffon  considers  as  the  seat  of  a sixth  sense.  In 
most  animals  the  lips,  and  especially  the  lower  one,  without 
feathers,  scales,  or  hair,  are  the  organ  of  a sort  of  touch,  imper- 
fect at  best.  When  the  domestic  quadrupeds,  such  as  the  horse, 
the  dog,  the  ox,  &c.  want  to  judge  of  the  tangible  qualities  of 
bodies,  you  will  see  them  apply  to  it  the  end  of  their  nose,  the 
only  part  where  the  external  covering  is  without  hair:  the  fleshy 
appendage.s  of  certain  birds,  and  many  fish,  the  antennae  of  butter- 
flies, always  set  near  the  opening  of  the  mouth,  answer  the  same 
purpose.  The  tail  of  the  beaver,  the  trunk  of  the  elephant,  are, 
in  like  manner,  the  parts  of  their  body  where  touch  is  most  deli- 
cate. Observe  that  the  perfection  of  the  organ  of  touch,  ensures 
to  these  two  animals  a degree  of  intelligence  allotted  to  nor  other 
quadruped,  and  becomes,  perhaps,  the  principle  of  their  sociabi- 
lity. The  books  of  travellers  and  naturalists  swarm  with  facts 
attesting  the  wonderful  sagacity  of  the  elephant.  Some  Indian 
philosophers  have  gone  the  length  of  allowing  him  an  immortal 
soul.  If  birds,  notwithstanding  the  prodigious  activity  of  their 
life  of  nutrition,  are  yet  of  such  confined  intelligence,  so  little 
susceptible  of  durable  attachment,  so  restive  to  education,  is  not 


352 


OF  SENSATIONS. 


the  cause  to  be  assigned  in  their  imperfection  of  touch?  In  vain' 
the  heart  sends  towards  all  their  organs,  with  more  force  and 
velocity  than  in  any  other  animal,  a warmer  blood,  and  endu- 
ed, more  remarkably,  with  all  the  qualities  which  characterize 
arterial  blood.  In  vain  is  their  digestion  rapid,  their  muscular 
power  lively,  and  capable  of  long  continued  motion;  certain  of 
their  senses,  as  those  of  sight  and  hearing,  happily  disposed; 
touch  being  almost  nothing  with  them,  as  also  the  greater  num- 
ber of  impressions  belonging  to  this  sense,  which  informs  us  of 
the  greater  part  of  the  properties  of  bodies,  the  circle  of  their 
ideas  must  be  extremely  narrow,  and  their  habits  and  man- 
ners much  more  remote  than  those  of  quadrupeds  from  the 
habits  and  manners  of  man. 

CXXXVI.  Of  all  the  senses,  the  touch  is  the  most  generally 
diffused  among  animals.  All  possess  it,  from  man  who,  in  the 
perfection  of  this  sense,  excels  all  vertebral  animals,  to  the 
polypus,  who,  confined  to  the  sense  of  touch  only,  has  it  in  such 
delicacy,  that  he  appears,  to  use  a happy  expression  of  M.  Du- 
meril,  to  feel  even  light.  The  skin  of  man  is  more  delicate, 
fuller  of  nerves  than  that  of  the  other  mammiferse;  its  surface  is 
covered  only  by  the  epidermis,  insensible  indeed,  but  so  thin 
that  it  does  not  intercept  sensation;  whilst  the  hairs  which  cover 
so  thickly  the  body  of  quadrupeds,  the  feathers  which  clothe 
that  of  birds,  quite  deaden  it.  The  hand  of  man,  that  admirable 
instrument  of  his  intelligence,  of  which  the  structure  has  ap- 
peared to  some  philosophers,*  to  explain  sufficiently  his  supe- 
riority over  all  living  species;  the  hand  of  man,  naked,  and 
divided  into  many  moveable  parts,  capable  of  changing  every 
moment  its  form,  of  exactly  embracing  the  surface  of  bodies,  is 
much  fitter  for  ascertaining  their  tangible  qualities  than  the  foot 
of  the  quadruped,  enclosed  in  a horny  substance,  or  than  that  of 
the  bird,  covered  with  scales  too  thick  not  to  blunt  all  sensation. 

CXXXVII.  Of  the  nerves.  These  whitish  cords  which  arise 
from  the  base  of  the  brain,  and  from  the  medulla  oblongata,  are 
distributed  to  all  parts  of  the  body,  and  give  them  at  once  the 
power  of  moving  and  feeling.  In  this  analysis  of  the  functions 
of  the  nervous  system,  the  most  natural  order  is  to  consider 

• See  the  work  of  Galen,  de  usu  partium,  cap.  4,  5,  6;  and  BufTon,  Hisicire 
Naturelle,  tom.  IV.  et  V.  12mo. 


OF  SENSATIONS. 


353 

them  merely  as  conductors  of  the  power  of  sensation.  We  shall 
then  see,  in  what  manner  they  transmit  the  principle  of  motion 
to  the  organs  by  which  it  is  performed.  The  nerves  arise,*  from 
all  sentient  parts,  by  extremities  that  are,  in  general,  soft  and 
pulpy,  but  not  alike  in  all  in  consistence  and  form;  and  it  is  to 
these  varieties  of  arrangement  and  structure,  that  the  varieties 
of  sensation  in  the  different  organs  are  to  be  referred. 

One  may  say  that  there  exists,  in  the  organs  of  sense,  a cer- 
tain relation  between  the  softness  of  the  nervous  extremity,  and 
the  nature  of  the  bodies  which  produce  an  impression  upon  it. 
Thus,  the  almost  fluid  state  of  the  retina,  bears  an  evident  re- 
lation to  the  subtility  of  light.  The  contact  of  this  fluid  could 
not  produce  a sufficient  impression,  unless  the  sentient  part  were 
capable  of  being  set  in  motion  by  the  slightest  impression.  The 
portio  mollis  of  the  seventh  pair,  wholly  deprived  of  its  solid 
covering,  and  reduced  to  its  medullary  pulp,  readily  partakes  in 
the  sonorous  motions  transmitted  to  it  by  the  fluid,  in  the  midst 
of  which  its  filaments  are  immersed.  The  nerves  of  smell  and 
of  taste,  are  more  exposed  than  the  nervous  papillae  of  the  skin, 
employed  in  receiving  the  impressions  produced  by  the  coarser 
properties  of  bodies,  &c. 

From  their  origin,  the  nerves  ascend  towards  the  medulla 
oblongata  and  the  spinal  marrow,  in  a line  nearly  straight,  and 
seldom  tortuous,  as  most  of  the  vessels.  When  they  have  reach- 
ed these  parts,  they  terminate  in  them,  and  are  lost  in  their  sub- 
stance, as  will  be  mentioned  in  speaking  of  the  structure  of  these 
nervous  cords. 

CXXX  VIII.  Every  nerve  is  formed  of  a great  number  of  fila- 
ments, extremely  delicate,  and  which  have  two  extremities,  the 
one  in  the  brain  and  the  other  from  the  part  into  which  they 

* In  considering  the  nerves  as  conductors  of  sensation,  it  is  correct  to  say, 
that  they  arise  from  sentient  parts,  since  it  is  the  extremity  most  distant  from 
the  brain,  which  experiences  the  sensitive  impression,  that  is  propagated  to  the 
organ  itself,  along  the  course  of  the  nerve.  In  attending,  on  the  contrary,  to 
the  phenomena  of  motion,  the  nerves  are  considered  to  arise  from  the  brain; 
for,  it  is  from  the  centre  to  the  circumference,  that  the  principle  of  motion  is 
transmitted  to  the  muscles  called,  by  Cullen,  moving  extremities  of  the  nerves. 
Some  anatomists  have  considered  it  as  a doubtful  point,  whether  the  nerves 
arise  from  the  brain  and  spinal  marrow,  or  whether  these  parts  are  formed  by 
the  union  of  the  nerves. 

2 Y 


354 


OF  SENSATIONS. 


terminate,  or  from  which  they  originate.  Each  of  these  nervous 
fibres,  however  minute,  is  composed  of  a membranous  tube, 
which  is  a production  of  the  pia  mater.  Within  the  parietes  of 
this  tube,  there  are  distributed  innumerable  vessels  of  extreme 
minuteness;  it  is  filled  within  with  a whitish  marrow,  a kind  of 
pulp,  which  Reil  states  he  insulated  from  the  small  canal  con- 
taining it,  by  concreting  it,  by  means  of  the  nitric  acid,  which 
dissolves  the  membranous  sheath,  and  leaves  uncovered  the  me- 
dullary pulp  forming  the  essential  part  or  basis  of  the  nervous 
filament.  This  same  physiologist  discovered,  by  a different  pro- 
cess, the  internal  structure  of  each  nervous  fibrilla;  he  dissolved 
the  whitish  or  pulpy  part,  by  a long  continued  solution  in  an  al- 
kaline ley,  and  he  succeeded  thus  in  separating  it  from  the  mem- 
branous tube  which  enclosed  it  and  which  was  emptied.  The 
membranous  sheath  is  of  cellular  structure,  and  is  remarkable 
only  by  its  consistence  and  by  the  very  considerable  number  of 
vessels  of  all  kinds  that  are  distributed  to  its  parietes;  it  ceases 
to  cover  the  nerves  near  their  two  extremities,  and  protects 
them  only  along  their  course. 

Each  nervous  fibre,  thus  formed  of  two  very  distinct  parts, 
joins  other  fibres  of  a perfectly  similar  structure,  to  form  a ner- 
vous filament  enveloped  in  a common  sheath  of  cellular  tissue. 

These  filaments,  by  their  union,  form  small  ramifications,  and 
these  progressively  larger  branches,  and  lastly,  trunks  wrapped 
in  a common  covering  of  cellular  tissue;  then  other  envelopes 
to  each  fasciculus  of  filaments,  and  lastly,  a sheath  to  each  in- 
dividual filament.  When  nervous  cords  are  of  a certain  size, 
veins  and  arteries  of  a pretty  considerable  caliber,  may  be  seen 
to  insinuate  themselves  between  the  bundles  of  fibres  of  which 
they  are  composed;  these  vessels  then  divide,  after  penetrating 
among  them,  and  furnish  the  capillar}'^  ramifications  which  are 
distributed  to  the  parietes  of  the  sheath  common  to  each  fila- 
ment. These  small  vessels,  according  to  Reil,  allow  the  nervous 
substance  to  exhale  into  each  membranous  tube;  this,  likewise, 
becomes  the  secretory  organ  of  the  medulla  with  which  it  is 
filled. 

CXXXIX.  The  nervous  filaments  unite,  or  are  separated 
from  one  another,  but  do  not  run  into  each  other.  The  divi- 
sions of  the  nerves  are  different  from  those  of  the  arteries,  and 


OF  SENSATIONS. 


355 


their  mode  of  junction  does  not  admit  of  being  compared  to 
that  of  the  veins.  It  is,  in  the  first  instance,  a mere  separation; 
in  the  second,  an  approximation  of  filaments  which  had  been  se- 
parated, and  which,  though  united  in  common  sheaths,  have, 
nevertheless,  each  a proper  covering,  are  merely  in  juxta  posi- 
tion and  perfectly  distinct.  If  that  were  not  the  case,  one  could 
not  say,  that  each  fibre  has  one  extremity  in  the  brain,  and  the 
other  in  some  one  point  of  the  body;  nor  could  one  conceive 
how  the  impressions  which  several  sentient  extremities  receive 
at  once,  reach  the  brain  without  running  into  each  other;  nor,  in 
what  manner  the  principle  of  motion  could  be  directed  towards 
a single  muscle  receiving  its  nerves  from  the  same  trunk  as  the 
other  muscles  of  the  limb. 

In  general,  the  nerves  divide  from  each  other  and  unite  at  an 
angle  more  or  less  acute,  and  equally  favourable  to  the  circula- 
lation  of  a fluid,  from  the  circumference  to  the  centre,  and  from 
the  centre  to  the  circumference. 

The  structure  of  the  nerves  is  different  according  to  their  situa- 
tion. Thus,  the  medullary  fibres  of  the  optic  nerve  are  not  fur- 
nished with  membranous  coverings,  the  pia  mater  alone  furnish- 
ing a sheath  to  the  cord  formed  by  the  union  of  these  filaments; 
the  dura  mater  adds  a second  coat  to  it,  on  its  leaving  the  skull. 
This  coat,  belonging,  likewise,  to  the  whole  nerve,  is  not  con- 
tinued over  it,  after  it  has  entered  the  eye  ball,  and  is  lost  in 
the  sclerotica.  A minute  artery  passes  through  the  centre  of 
the  optic  nerve,  and  then  dividing,  forms  a rete  mirabile  which 
supports  the  medullary  pulp  of  the  retina.  The  nerves  which 
pass  along  osseous  canals,  as  the  Vidian  nerve  of  the  fifth  pair, 
are  not  provided  with  a cellular  covering,  and  their  consistence 
is  always  greater  than  that  of  the  nerves  which  are  surrounded 
by  soft  parts. 

CXL.  On  reaching  the  brain,  the  medulla  oblongata,  or  the 
spinal  marrow,  every  nervous  filament,  as  was  already  mention- 
ed, parts  with  its  membranous  covering,  which  is  lost  in  the  pia 
mater,  or  immediate  covering  of  these  central  parts  of  the  brain. 
The  medullary  or  white  part  of  the  brain  is  continued  into  their 
substance,  which  may  be  considered  as  principally  formed  by 
the  assemblage  of  these  nervous  extremities,  which  it  is  diffi- 
cult to  distinguish  in  its  tissue,  from  its  want  of  consistence.  It 


356 


OF  SENSATIONS. 


has  long  been  known,  that  the  origin  of  the  nerves  is  not  the 
spot  at  which  they  are  detached  from  the  brain,  that  they  sink 
into  the  substance  of  this  viscus,  in  which  their  fibres  cross  each 
other,  so  that  those  on  the  right  pass  to  the  left,  and  vice  versa. 
Scemmering  thought,  that  the  roots  of  the  nerves,  especially  of 
the  nerves  of  the  organs  of  sense,  reached  to  the  prominences  in 
the  parietes  of  the  ventricles  of  the  brain,  and  that  their  furthest 
extremity  was  moistened  by  the  serosity  which  keeps  these  in- 
ward surfaces  in  contact.  It  has,  likewise,  long  been  thought, 
that  the  cerebral  extremities  of  the  nerves  all  joined  in  a fixed 
point  of  the  brain,  and  that  to  this  central  point  all  sensations 
were  carried,  and  that  from  it,  all  the  determinations  producing 
voluntary  motion  arose.  But  the  inquiries  of  Gall  on  the  struc- 
ture of  the  brain  and  nervous  system,  have  completely  overset 
these  various  hypotheses. 

The  spinal  marrow  and  the  nerves,  in  the  diff erent  animals 
furnished  with  them,  are  larger  in  proportion  to  the  brain,  ac- 
cording as  the  animal  is  more  distant  from  roan  in  the  scale  of 
aniroation.  In  carnivorous  animals,  the  prodigious  develop- 
ment of  the  muscles  required  nerves  of  motion  of  a proportion- 
ate size;  hence,  in  them,  the  cerebral  mass,  compared  to  the 
nerves  and  spinal  marrow,  is  very  inconsiderable.  It  is  ob- 
served, that  there  exists  the  same  relation  in  men  of  an  athle- 
tic disposition;  the  whole  nervous  power  seems  employed  in 
moving  their  large  muscles,  and  the  nerves,  though  very  small, 
in  proportion  to  the  rest  of  the  body,  are,  however,  very  large, 
if  compared  to  the  cerebral  organ.  In  children,  in  women,  and 
in  individuals  possessed  of  much  sensibility,  the  nerves  are  very 
large,  in  proportion  to  the  other  parts  of  the  body;  they  de- 
crease in  size  and  shrink  in  persons  advanced  in  years;  the  cel- 
lular tissue  which  surrounds  them,  becomes  more  consistent, 
adheres  to  them  more  closely,  and  there  exists  a certain  analogy 
between  the  nerves  of  old  men,  enveloped  by  that  yellowish 
tissue  which  makes  their  dissection  laborious,  and  the  branches 
of  an  old  tree  covered  over  by  a destructive  moss. 

As  the  uses  of  the  nerves  cannot  be  explained  independently 
of  those  of  the  brain,  I shall  now  go  on  to  consider  this  impor- 
tant viscus. 

CXLI.  Of  the  coverings  of  the  brain.  If  it  be  true,  that  one 


OF  SENSATIONS. 


357 

may  judge  of  the  importance  of  an  organ  by  the  care  which  na- 
ture has  taken  to  protect  it  from  external  injury,  no  organ  will 
appear  of  greater  importance  than  the  brain,  for  no  one  appears 
to  have  been  protected  with  greater  care.  The  substance  of  this 
viscus  has  so  little  consistence,  that  the  slightest  injury  would 
have  altered  its  structure,  and  deranged  its  action;  hence  it  is 
powerfully  guarded  by  several  envelopes,  the  most  solid  of 
which  is  the  bony  case  in  which  it  is  contained. 

No  part  of  anatomy  is  better  understood  than  that  of  the 
many  bones  which,  by  their  union,  form  the  different  parts  of 
the  human  head.  Every  thing  that  relates  to  the  place  they  oc- 
cupy, to  their  respective  size,  to  their  projections  and  depres- 
sions, to  the  cavities  whose  parietes  they  form;  every  thing  that 
relates  to  their  internal  structure,  to  the  different  proportions  of 
their  component  parts,  to  the  aggregation  of  some  of  these  sub- 
stances, in  certain  points  of  their  extent;  has  been  described  by 
several  modern  anatomists,  with  an  accuracy  which  it  would  not 
be  easy  to  surpass.  Several,  however,  have  not  sufficiently  ap- 
preciated the  direct  influence  of  their  mode  of  action  on  the 
functions  which  they  are  destined  to  fulfil;  no  one  has  insisted 
sufficiently  on  the  manner  in  which  they  all  concur  to  a princi- 
pal object;  the  preservation  of  the  organs  enclosed  within  the 
skull. 

Hunauld,  in  a memoir  inserted  among  those  of  the  Academy 
of  Sciences,  for  the  year  1730,  was  the  first  that  endeavoured  to 
account  for  the  arrangement  of  the  articulating  surfaces  of  the 
bones  of  the  skull.  After  laying  down  a few  principles  on  the 
theory  of  arches,  and  after  showing,  that  the  difference  of  ex- 
tent of  their  concave  and  convex  surfaces,  rendered  it  necessary 
that  the  parts  of  which  they  are  forrhed  should  be  shaped  ob- 
liquely, he  explains  the  advantages  of  the  squamous  articulation 
between  the  temporal  and  parietal  bones. 

When  the  arch  of  the  cranium  is  loaded  with  a very  heavy 
burthen,  the  temporal  bones  prevent  the  parietals  on  which  the 
effort  is  immediately  applied,  from  being  forced  inwardly,  or 
from  being  separated  outwardly.  Hunauld  very  aptly  compares 
them  to  buttresses,  which  are  to  the  parietal  bones  of  the  same 
use  as  walls  to  the  arches  which  they  support. 


358 


OF  SENSATIq^"S. 


Borden*  endeavoured  to  apply  to  the  bones  of  the  face,  the 
principles  by  which  Hunauld  had  been  guided  in  his  investiga- 
tion with  regard  to  those  of  the  skull.  According  to  Bordeu,  the 
greater  part  of  the  bones  of  the  upper  jaw,  but  particularly  the 
superior  maxillary  bones,  resist  the  effort  of  the  lower  jaw, 
which,  by  acting  on  the  upper  dental  arch,  has  a perpetual  ten- 
dency to  force  upward,  or  to  separate  outwardly  the  bones  in 
which  the  teeth  of  that  jaw  are  inserted.  As  the  greatest  stress 
of  the  effort  determines  them  upward,  it  is,  likewise,  in  that  di- 
rection, that  the  bones  of  the  upper  jaw  rest  most  powerfully 
on  those  of  the  skull.  The  author  concludes  this  very  ingenious 
memoir,  by  proposing  to  physiologists  the  solution  of  the  fol- 
lowing problem:  “ When  a man  supports  a great  weight  on  his 
“ head,  and  holds  at  the  same  time  any  thing  very  firmly  be- 
“ tween  his  teeth,  which  is  the  bone  of  the  head  that  is  most 
“ acted  upon?  Which  supports  the  weight  of  the  whole  machine?” 

The  body  of  the  sphenoid,  and  especially  its  posterior  half, 
appears  to  me  to  be  the  central  point  on  which  the  united  efforts 
of  the  bones  of  the  skull  and  of  the  face  act,  in  the  case  supposed 
b)f  Bordeu. 

The  sphenoid  is  connected  with  all  the  other  bones  of  the 
skull;  it  is  immediately  connected  with  several  of  the  bones  of 
the  face:  as  with  the  malar  bones,  with  the  palatine  bones,  with 
the  vomer,  and  sometimes  with  the  superior  maxillary  bones. 
These  bones  of  the  face,  in  the  case  in  question,  alone  support 
the  lower  jaw  against  the  upper.  The  ethmoid  bone,  the  ossa 
unguis,  and  the  inferior  turbinated  bones  are  thin  and  frail,  and 
serve  merely  to  form  the  nasal  fossse,  of  which  they  increase  the 
windings,  and  do  not  deserve  to  be  attended  to  in  this  investiga- 
tion. The  vomer  may,  it  is  true,  communicate  to  the  ethmoid, 
in  an  inferior  degree,  a part  of  the  effort;  for  the  anterior  part 
of  its  upper  edge  is  articulated  with  the  perpendicular  lamella 
of  that  bone;  but  this  quantity  is  very  small,  as  the  vomer  is 
thin,  and  transmits  it  almost  wholly  to  the  body  of  the  sphenoid, 
with  the  lower  face  of  which  it  is  articulated. 

The  effort  exerted  on  the  bones  of  the  upper  jaw,  is  trans- 
mitted, by  means  of  the  nasal  processes  of  the  upper  maxillary 

* Academic  des  Sciences,  Alemoires prdsent^s par  les  savans  Strangers.  Tome  III. 


OF  SENSATIONS. 


359 


bones,  by  the  orbitar  and  zygomatic  processes  of  the  malar 
bones,  and  by  the  upper  edge  of  the  palate  bones  and  of  the  vo- 
mer, to  the  frontal,  to  the  temporal,  and  sphenoidal  bones. 

If  we  wish  to  determine  what  becomes  of  the  greater  part  of 
the  effort  transmitted  to  the  frontal  bone  by  the  maxillary  and 
malar  bones,  we  may  observe,  in  the  first  place,  that  it  is  arti- 
culated with  the  sphenoid  bone  by  the  whole  of  its  lower  edge, 
which  is  bevelled  at  its  inner  part,  so  that  it  is  covered  by  the 
alse  minores  of  the  os  sphenoides,  which  is  shaped  obliquely  at 
the  outer  part  of  the  bone.  The  frontal  bone  is  articulated,  be- 
sides, with  the  lateral  and  inferior  parts  of  its  upper  edge.  The 
remainder  of  this  upper  part  is  united  to  the  anterior  edge  of 
the  parietal  bones,  which,  by  means  of  a slope  in  a different  di- 
rection rest  on  the  middle  part  of  this  edge,  while  the  frontal 
bone  is  applied  to  them  laterally. 

This  bone,  which  the  effort  tends  to  force  upward  and  back- 
ward, cannot  yield  to  this  double  impulse;  for,  on  the  one  hand^ 
its  mode  of  articulation  with  the  anterior  edge  of  the  alse  mi- 
nores of  the  sphenoidal  bone,  and  the  internal  part  of  the  ante- 
rior edge  of  the  parietal  bones,  resist  this  tendency  upward, 
while  the  resistance  from  the  latter  prevents  them  from  being 
forced  backward.  That  share  of  the  effort  which  affects  the 
parietal  bones,  follows  the  curved  line  described  by  these 
bones,  and  extends  along  that  formed  by  the  occipital,  and  thus 
reaches  the  posterior  face  of  the  body  of  the  sphenoid  bone. 

The  portion  directly  transmitted  to  the  anterior  and  inferior 
face  of  this  bone,  by  the  ossa  palati,  and  by  the  vomer,  is  incon- 
siderable, and  proportioned  to  their  thinness.  The  anterior  half 
of  the  body  of  the  sphenoid  bone,  hollowed  by  the  sphenoidal 
sinus,  would  have  been  incapable  of  supporting  greater  pres- 
sure. Lastly,  the  situation  of  the  body,  placed  between  the 
dental  arches,  in  front  of  the  place  occupied  by  the  ossa  palati, 
explains  why  this  transmission  is  chiefly  effected  by  the  upper 
maxillary  bones. 

The  above  is  the  manner  in  which  the  effort  exerted  from 
below  upward,  by  the  lower  on  the  upper  jaw,  is  carried  to  the 
anterior,  posterior,  and  inferior  faces  of  the  body  of  the  sphenoid 
bone. 


360 


OF  SENSATIONS. 


The  temporal  bones  which  are  affected  by  it,  in  a very  slight 
degree,  by  means  of  the  zygomatic  processes  of  the  malar  bones, 
support  the  greater  weight  of  the  effort  acting  from  above  down- 
ward, or  from  the  arch  of  the  skull  towards  its  base.  The  weight 
laid  on  the  head,  tends  to  depress  or  to  separate  the  parietal 
bones,  which  resist  the  pressure,  in  consequence  of  the  support 
afforded  them  by  the  temporals.  These  transmit  the  effort  to 
the  lateral  and  posterior  parts  of  the  body  of  the  sphenoid,  by 
means  of  the  alse  majores  of  that  bone,  which  are  articulated, 
along  the  whole  extent  of  their  external  edge,  and  along  the  pos- 
terior fourth  of  their  internal  edge,  with  the  temporals.  Besides, 
the  upper  extremity  of  the  alae  majores  is  sloped  on  the  inner 
part  of  the  bone,  that  it  may  be  articulated  with  the  anterior 
and  inferior  angles  of  the  parietal  bones,  and  answer  the  same 
purpose  to  them  as  the  squamous  portion  of  the  temporals. 

The  lateral  and  posterior  parts  of  the  body  of  the  sphenoid, 
support,  therefore,  almost  the  whole  effort  of  the  pressure  ap- 
plied to  the  parietal  bones.  It  is  communicated  to  them  by  the 
alae  majores,  which  receive  it  themselves,  either  directly  at  the 
anterior  and  inferior  angles  of  this  bone,  or  through  the  medi- 
um of  the  temporals.  The  small  portion  of  the  effort  trans- 
mitted by  the  latter  to  the  occipital,  follows  the  curved  line  of 
this  bone,  and  is  felt  on  the  posterior  face  of  the  body  of  the 
sphenoid. 

To  the  effort  resulting  from  the  pressure  exerted  by  the  body 
on  the  summit  of  the  head,  one  should  add  that  occasioned  by 
the  contraction  of  the  muscles,  which  elevate  the  lower  jaw. 
These  tend  to  depress  the  temporal,  the  malar,  and  sphenoid 
bones;  and  in  this  action  they  employ  a power,  equal  to  that  by 
which  they  raise  the  lower  jaw,  and  press  it  firmly  against  the 
upper. 

The  effort  exerted  from  the  arch  to  the  base  of  the  skull  de- 
pends, therefore,  on  two  very  different  causes;  the  portion  result- 
ing from  the  action  of  the  elevators  of  the  lower  jaw,  is  equal 
to  the  effort  exerted  from  below  upward,  by  this  bone.  After 
' what  has  been  stated,  it  would  be  useless  to  say  any  thing  fur- 
ther of  the  manner  in  which  the  effort  is  transmitted:  we  may 
merely  observe,  that  the  least  powerful  of  these  muscles,  the  in- 
ternal pterygoid,  tends  to  draw  the  sphenoid  downward,  and 


OF  SENSATIONS. 


361 


prevents  this  bone,  fixed  like  a wedge  with  its  base  turned  up- 
ward, from  being  disengaged  by  the  effort  applied  to  it  by  the 
bones  betvveen  which  it  is  situated. 

The  posterior,  anterior,  inferior  and  lateral  faces  of  the  sphe- 
noid bone,  support,  therefore,  the  whole  effort  of  the  bones  of 
the  skull  and  face  on  one  another,  when  the  top  of  the  head 
being  loaded  with  a heavy  burthen,  one  presses,  at  the  same 
time,  something  very  firmly  between  the  dental  arches. 

The  anterior  part  of  the  body  of  the  bone,  containing  the 
sphenoidal  sinus,  is  thin  and  very  frail;  the  posteri  .r  part,  cor- 
responding to  the  sella  turcica,  is  alone  capable  of  resisting  the 
effort  which,  I believe,  it  is  destined  to  sustain*;  hence,  it  is  at 
this  point,  that  ossification  begins:  and  this  confirms  the  obser- 
vation of  Kerkringius,  that  the  spot  at  which  bones  begin  to 
ossify,  is  that  on  which  they  have  to  bear  the  greatest  effort; 
hence  the  alas  majores,  by  means  of  which  the  greatest  part  of 
the  efforts  which  the  body  of  the  sphenoid  has  to  support,  arise 
from  the  lateral  parts  of  its  posterior  half,  by  an  origin  of  con- 
siderable size,  and  which  is  further  increased  by  the  base  of  the 
pterygoid  processes  which  arise  from  its  lower  part. 

I have,  in  this  enquiry,  purposely  avoided  mentioning  the 
support  which  the  head  receives  from  the  vertebral  column,  and 
which,  in  the  case  under  consideration,  is  of  use  merely  in  pre- 
venting it  from  yielding  to  the  law  of  gravitation.  If  ihe  bones 
of  the  skull  arid  of  the  face  had  pressed,  during  the  effort  which 
they  sustain,  on  the  circumference  of  the  foramen  magnum, 
this  aperture  would  have  been  incapal^le  of  increasing  its  di- 
mensions, and  this  would  have  been  attended  with  the  most 
serious  inconveniences. 

The  name  given  by  the  ancients  to  the  bone  whose  principal 
use  has  just  been  explained,  is  composed  of  sphenos,  which 

* The  sphenoidal  sinus  is  prolonged,  it  is  true,  into  this  posterior  part  of  the 
body  of  the  bone,  in  persons  considerably  advanced  in  years:  but  the  parietes 
of  this  portion  of  its  cavity  ai’e  of  considerable  thickness.  The-  anterior 
part  of  the  basilary  process  of  the  occipital  bone,  is  then  firmly  united  to 
the  sphenoid,  and  may  be  considered  as  forming  a part  of  that  bone,  from 
which  it  cannot  be  detached.  The  cranium  of  an  old  man,  in  this  respect,  re- 
sembles that  of  several  quadrupeds,  in  which  the  union  of  the  sphenoid  to  the 
occipital  bone  takes  place  so  early,  that  these  two  bones  might  well  be  con- 
sidered as  forming  but  one. 

2 Z 


362 


OF  SENSATIONS. 


means  a wedge,  and  eidos,  which  signifies  resemblance,  and 
would  lead  one  to  think  that  they  were  not  ignorant  of  its  uses. 
From  its  situation  at  the  middle  and  inferior  part  of  the  skull, 
and  from  its  various  connexions  with  the  bones  which  form  this 
osseous  case,  it  is  to  them  of  the  same  use  as  the  key-stone  of 
arches,  with  regard  to  the  different  parts  of  which  they  are  form- 
ed. The  numerous  connexions  required  for  this  purpose,  ac- 
count for  its  strange  and  irregular  form,  and  for  the  different 
shapes  of  its  articular  surfaces,  and  the  great  number  of  its  pro- 
jections, which  render  the  demonstration  of  this  bone  so  com- 
plicated, and  a knowledge  of  it  so  difficult. 

It  is  more  advantageous,  with  regard  to  the  brain,  that  the 
skull  should  be  formed  of  several  bones,  than  if  it  had  con- 
sisted of  a single  bone.  It  resists,  more  effectually,  the  blows 
it  receives,  their  effect  being  lessened  in  passing  from  one 
bone  to  the  other,  and  being  interrupted  in  the  obscure  motions 
which  they  may  experience  at  their  sutures;  its  rounded  form 
increases,  likewise,  its  power  of  resistance.  This  force  would 
be  equal,  in  every  point  of  the  parietes  of  the  cranium,  if  the 
form  of  that  cavity  were  completely  spherical,  and  if  the  thick- 
ness of  its  parietes  were,  in  every  part  of  it,  the  same.  In  that 
case,  no  fractures  by  contre  coup  could  occur,  a kind  of  lesion 
occasioned  by  the  unequal  resistance  of  the  bones  of  the  head, 
to  the  force  applied  to  their  surface.  The  pericranium,  the  hairy 
scalp,  the  muscles  which  cover  it,  and  the  great  quantity  of  hair 
on  its  surface,  serve,  besides,  to  defend  the  brain,  and  are  well 
calculated  to  break  the  force  of  blows  applied  to  the  cranium. 

In  addition  to  this  hard  and  unyielding  case,  there  lies  over 
the  brain,  a treble  membranous  covering,  formed  by  the  dura 
mater,  which  owes  its  name  to  the  erroneous  opinion  according 
to  which  it  was  supposed  to  form  all  the  other  membranes  of 
the  body;  it  is  further  covered  by  the  tupica  arachnoidea,  so 
called  from  the  extreme  minuteness  of  its  tissue,  and  by  the 
pia  mater  which  adheres  firmly  to  the  substance  of  the  brain. 

The  dura  mater  lines,  not  only  the  inside  of  the  skull  and 
of  the  vertebral  canal,  which  may  be  considered  as  a prolonga- 
tion of  it,  but,  likewise,  penetrates  between  the  different  parts  of 
the  cerebral  mass,  supports  them  in  the  different  positions  of 
the  head,  and  prevents  mutual -compression.  Thus,  the  greatest 


OF  SENSATIONS. 


363 

of  its  folds,  the  falx,  stretched  between  the  crysta  galli  of  the  eth- 
moid bone,  and  the  inner  protuberance  of  the  occipital  bone,pre- 
vents  the  two  hemispheres  of  the  brain,  between  which  it  lies, 
from  compressing  each  other,  when  the  body  is  on  the  side;  and 
maintains,  on  the  other  hand,  the  tentorium  cerebelli  in  the  state 
of  tension  necessary  to  enable  it  to  support  the  weight  of  the  pos- 
terior lobes  of  the  brain.  This  fold  of  dura  mater  is  of  a semi- 
circular form,  separates  the  portion  of  the  skull  which  contains 
the  brain,  from  that  in  which  the  cerebellum  is  situated.  It  is  kept 
in  a state  of  tension  by  the  falx  cerebri,  on  which  it  also  exerts 
the  same  action:  it  does  not  present  an  horizontal  plane  to  the 
portion  of  brain  which  lies  upon  it,  but  one  that  slopes,  in  every 
direction,  towards  the  parietes  of  the  skull,  to  which  it  trans- 
mits most  of  the  weight  which  it  has  to  support.  The  tentorium 
cerebelli,  which  thus  divides  the  internal  cavity  of  the  skull 
into  two  parts  of  unequal  dimensions,  is  bony  in  some  animals 
that  move  by  bounding  and  with  rapid  action;  this  is  the  case 
with  the  cat,  which  can,  without  being  stunned,  take  leaps  from 
a considerable  height.  By  means  of  this  complete  partition,  the 
two  portions  of  the  brain  are  prevented  from  pressing  on  each 
other,  in  the  violent  concussions  which  they  experience. 

The  tunica  arachnoides,  according  to  Bonn*,  who  was  tho- 
roughly acquainted  with  its  structure  and  who  has  given  a very 
beautiful  plate  of  it,  is  the  secretory  organ  of  the  serum  which 
moistens  the  internal  surface  of  the  dura  mater,  a fibrous  mem- 
brane which  serves  as  a periosteum  to  the  bones  it  lines. 

CXLII.  Of  the  size  of  the  brain.  Of  all  animals,  man  has 
the  most  capacious  skull,  in  proportion  to  his  face,  and,  as  the 
bulk  of  the  brain  is  always  of  a size  proportioned  to  that  of  the 
osseous  case  which  contains  it,  the  brain  is  also  most  bulky  in 
man.  This  difference  of  size  between  the  cranium  and  face,  may 
be  taken  as  the  measure  of  the  human  understanding  and  of  the 
instinct  of  the  lower  animals;  the  stupidity  and  ferocity  of  the 
latter  are  greater,  according  as  the  proportions  of  these  two 
parts  of  their  skull  vary  from  those  of  the  human  head. 

To  express  this  difference  of  size.  Camper  imagined  a verti- 
cal line,  drawn  from  the  forehead  to  the  chin,  and  perpendicular 


Dissertatio  de  continuationibus  membranarum.  4?  Lugdun.  Bat.  1763. 


364  SENSATIONS. 

to  another  drawn  in  the  direction  of  the  base  of  the  skull.  He 
has  called  the  first  of  these  lines  facial^  the  second, or 
mental.  It  is  easy  to  understand,  that,  as  the  projection  of  the 
forehead  is  determined  by  the  size  of  the  skull,  the  larger  it  is, 
the  more  the  angle  at  which  the  facial  line  meets  that  from  the 
base  of  the  skull  must  be  obtuse.  In  a well  formed  European 
head,  the  fascial  line  meets  the  palatine  at  an  angle  nearly  straight 
(of  between  80  and  90  degrees).  When  the  angle  is  quite 
straight,  and  the  line  which  measures  the  height  of  the  face  is 
completely  vertical,  the  head  is  of  the  most  beautiful  form  pos- 
sible, it  approaches  most  to  that  conventional  degree  of  perfec- 
tion which  is  termed  ideal  beauty.  If  the  facial  line  slopes 
backward,  it  forms  with  the  palatine  line,  an  angle  more  or  less 
acute,  and  projecting  forward,  the  inclination  increases,  and  the 
sinus  of  the  angle  is  shorter;  if,  from  man,  we  pass  to  monkeys, 
then  to  quadrupeds,  to  birds,  reptiles,  and  fishes,  we  find  this 
line  slope  more  and  more,  and,  at  last,  become  almost  parallel 
to  the  mental,  as  in  reptiles  and  in  fishes,  with  flat  heads.  If,  on 
the  contrary,  we  ascend  from  man  to  the  gods,  whose  images 
have  been  transmitted  to  us  by  the  ancients,  we  find  the  facial 
line  to  incline  in  a different  direction,  the  angle  then  enlarges 
and  becomes  more  or  less  obtuse.  From  this  inclination  for- 
ward of  the  facial  line,  there  results  an  air  of  grandeur  and 
majesty,  a projecting  forehead,  indicating  a voluminous  brain 
and  a divine  intellect. 

To  obtain  with  precision,  by  this  means,  the  respective  di- 
mensions of  the  skull  and  face,  one  must  measure,  not  only  the 
outside,  but,  likewise,  draw  the  tangents  on  the  internal  sur- 
faces, after  dividing  the  head  vertically.  There  are,  in  fact, 
animals,  in  which  the  sinuses  of  the  frontal  bone  are  so  large, 
that  a considerable  portion  of  the  parietes  of  the  skull  is  pro- 
truded by  their  cells.  Thus,  in  the  dog,  in  the  elephant.  In  the 
owl,  &c.  the  apparent  size  of  the  skull  exceeds  much  its  real 
capacity. 

The  relative  size  of  the  head,  and  consequently  the  propor- 
tionate bulk  of  the  brain,  is  inconsiderable  in  very  tall  and  mus- 
cular subjects;  this  fact  will  be  confirmed  by  observing  the  pro- 
portions of  antique  statues.  In  all  those  which  represent  heroes 
or  athlets  gifted  with  a prodigious  bodily  power,  the  head  is 


OF  SENSATIONS. 


365 


very  small,  in  proportion  to  the  rest  of  the  body.  In  the  statues 
of  Hercules,  the  head  scarcely  equals  in  size  the  top  of  the  shoul- 
der. The  statutes  alone  of  the  king  of  the  gods,  present  the  sin- 
gular combination  of  an  enormous  head,  resting  on  limbs  of  a 
proportionate  size;  but  the  Greek  artists  have  transgressed 
the  laws  of  nature,  only  in  favour  of  the  god  that  rules  over 
her;  as  if  a vast  brain  had  been  necessary  to  one  whose  intellect 
carries  him,  at  a glance,  over  the  whole  universe.  The  relative 
small  dimensions  of  the  head,  in  athlets,  depend  on  this  circum- 
stance, that  in  such  men,  the  excessive  development  of  the 
organs  of  motion,  gives  to  the  body,  and  especially  to  the  limbs, 
an  enormous  size,  while  the  head  covered  by  few  muscles, 
remains  very  small.  Scemmering  has  stated,  that  the  head  in 
women  is  larger  than  in  men,  and  that  their  brain  is  heavier;  but 
it  must  be  recollected,  that  this  great  anatomist  obtained  this 
result,  by  examining  two  bodies,  male  and  female,  of  the  same 
length.  Now,  the  absolute  size  being  the  same,  the  proportion- 
ate magnitude  was  not  so,  and  he  was  wrong  in  comparing  the 
head,  the  skull,  and  brain  of  a very  tall  woman,  to  that  of  a very 
short  man. 

It  has  long  been  thought,  that  there  exists  a connexion  be- 
tween the  bulk  of  the  cerebral  mass  and  the  energy  of  the  intel- 
lectual faculties.  It  has  been  thought,  that,  in  general,  men 
whose  mind  is  most  capacious,  whose  genius  is  most  capable  of 
bold  conceptions,  had  a large  head  supported  on  a short  neck. 
The  exceptions  to  this  general  rule  have  been  so  numerous, 
that  many  have  doubted  its  truth;  should  it  then  be  absolutely 
rejected,  and  will  it  be  allowed  to  be  wholly  without  foundation, 
when  we  consider  that  man,  the  only  rational  being  out  of  so 
great  a number,  and  some  of  which  bear  to  him  a considerable 
resemblance  both  of  organization  and  structure,  is,  likewise,  the 
only  animal  in  which  the  brain,  properly  so  called,  is  largest  in 
proportion  to  the  cerebellum,  to  the  spinal  marrow,  to  the  nerves 
and  to  the  other  parts  of  the  body?  Why  may  it  not  be  with  the 
brain,  as  with  the  other  organs,  which  fulfil  their  functions  the 
better,  from  being  more  completely  developed?  It  should  be  re- 
collected, in  this  comparison  of  the  brain  and  of  the  intellectual 
powers,  that  several  causes  ma)^  give  to  this  viscus  an  unnatu- 
ral degree  of  enlargement.  Thus,  in  subjects  of  a leucophleg- 


366 


OF  SENSATIONS. 


matic  temperament,  the  tardy  ossification  of  the  bones  of  the 
skull,  causes  the  brain,  gorged  with  aqueous  fluids,  to  acquire 
a considerable  size,  without  its  containing  a greater  quantity  of 
real  medullary  substance.  Hence  it  is  observed,  that  men  of 
this  temperament  are,  most  frequently,  unfit  for  mental  exer- 
tion, and  rarely  succeed  in  undertakings  that  require  activity 
and  perseverance*. 

CXLIII.  Structure  of  the  cerebral  mass.  What  we  know  of 
the  brain,  serves  only  to  show  us  that  we  are  ignorant  of  much 
more.  All  that  we  know  of  it  consists  of  notions  tolerably  ex- 
act of  its  external  conformation,  its  colour,  its  density,  and  of 
the  diflferent  substances  that  enter  into  its  composition;  but  the 
knowledge  of  its  intimate  structure  is  yet  a mystery,  which  will 
not  be  soon  unveiled  to  us.  The  brain,  properly  called,  is  divi- 
ded by  a longitudinal  furrow,  into  two  lobes  of  equal  bulk. 
Gunzius,  however,  imagined  that  he  found  the  right  lobe,  or 
hemisphere,  a little  larger  than  the  left;  but  even  were  this  fact 
as  certain  as  it  is  doubtful,  we  could  not  thereby  explain  the 
predominant  force  of  the  right  side  of  the  body,  since  the  nerves 
which  are  distributed  to  this  side,  rise  from  the  left  lobe  of  the 
brain,  in  the  substance  of  which  all  the  roots  of  these  cords 
cross.  This  fact  of  the  crossing  of  the  nerves,  at  their  origin,  is 
proved  by  a multitude  of  pathological  observations,  in  which 
the  injury  of  a lobe  is  always  found  to  bring  on  paralysis,  con- 
vulsion, or  any  other  symptomatic  affection,  on  the  opposite  side 
of  the  body.  Unless  you  chuse  to  explain  this  phenomenon  by 
admitting  a necessary  equilibrium  in  the  action  of  the  two  lobes; 
an  equilibrium,  the  disturbance  of  which  is  the  occasion  that  the 
sound  lobe,  acting  with  more  force,  compresses  the  origin  of 
the  nerves  on  its  side,  and  determines  paralysis.  May  not  the 
want  of  judgment,  the  unevenness  of  humour  and  character, 
depend  on  the  want  of  harmony  between  the  two  corresponding 
halves  of  the  cerebral  mass? 

In  order  to  disclose,  better  than  had  before  been  done,  the 
structure  of  the  brain,  M.  Gall  begins  his  dissection  at  the 
lower  part;  examining,  in  the  first  place,  the  anterior  part  of  the 

* See,  in  the  article  on  Temperaments,  an  account  of  the  influence  of  the 
physical  organization  on  the  moral  disposition  and  on  the  intellectual  faculties. 


OF  SENSATIONS. 


367 

prolongation  known  under  the  name  of  cauda  of  the  medulla 
oblongata,  he  finds  the  two  pyramidal  eminences.  If  you  part 
the  two  edges  of  the  median  line,  below  the  furrow  which  sepa- 
rates the  two  pyramids,  you  see  distinctly  the  crossing  of  three 
or  four  cords  or  fasciculi  of  nerves,  which,  consisting  of  many 
filaments,  tend  obliquely  from  right  to  left,  and  vice  versa.  This 
crossing  of  nervous  fibres,  which  is  not  found  in  any  other  part 
of  the  brain,  had  been  observed  by  several  anatomists.  It  is  not 
known  how  it  came  to  be  forgotten,  so  that  the  most  exact  and 
the  latest  among  them,  Boyer,  for  instance,  say  that  the  cross- 
ing of  the  nerves  cannot  be  proved  by  anatomy.  These  nervous 
cords,  traced  upwards,  enlarge,  strengthen,  and  forming  pyra- 
midal eminences,  ascend  towards  the  tuber  annulare.  Having 
reached  this  ganglion;  the  fibres  strike  Into  it,  and  are  lost  in  a 
mass  of  pulpy  or  grayish  substance,,  of  the  same  nature  as  that, 
which,  under  the  name  of  cortical  substance,  covers  the  two 
lobes  of  the  brain.  This  grayish  pulp,  distributed  in  various 
parts,  may  be  considered,  agreeably  to  the  views  of  M.  Gall, 
v.'ho  calls  it  the  matrix  of  the  nerves,  as  the  source  from  which 
the  medullary  fibres  take  their  origin.  These  ascending  fibres 
cross  other  transverse  fibres,  which,  on  either  side,  proceed  from 
the  crura  of  the  cerebellum;  enlarged  and  multiplied  by  means 
of  their  passage  through  the  gray  substance  which  is  found  in 
the  tuber  annulare,  they  rise  from  it  at  its  upper  part,  in  two  fas- 
ciculi which  compose  nearly  the  whole  of  the  crura  cerebri.  The 
interior  of  these  crura,  contains  a certain  quantity  of  gray  sub- 
stance, which  is  what  nourishes  the  nervous  fibre.  On  reaching 
the  ventricles,  these  peduncles,  or  rather  the  two  fasciculi  of 
fibres  which  form  them,  meet  with  large  ganglions  full  of  gray 
substance;  they  have  long  been  called  thalami  optici,  though  they 
do  not  give  origin  to  the  optic  nerves.  There  the  fibres  are  sen- 
sibly enlarged;  and  they  pass  from  the  thalami  optici  into  new 
ganglions.  These  are  the  corpora  striata,  and  the  striae  which  are 
apparent  on  cutting  these  pyriform  masses  of  gray  substance, 
are  only  the  same  fibres,  which,  enlarged,  multiplied,  and  ra- 
diating, spread  out  in  the  manner  of  a fan,  towards  the  lobes  of 
the  brain,  where,  after  forming  by  their  expansion  a whitish  and 
fibrous  substance,  they  terminate  at  the  outer  part  of  that  viscus, 
forming  its  convolutions,  all  covered  with  the  substance  in  which 


368 


OP  SENSATIONS, 


are  terminated,  in  like  manner,  the  extremities  of  the  div^ging 
fibres.  From  this  gray  substance  proceed  converging  fibres, 
tending  from  all  parts  of  the  periphery  to  the  centre  of  the 
brain,  where  they  unite  to  form  the  different  commissures,  the 
corpus  callosum,  and  other  productions,  destined  to  facilitate 
the  communication  of  the  two  hemispheres. 

The  exterior  of  the  brain  may,  therefore,  be  considered  as  a 
vast  nervous  membrane,  formed  by  the  gray  substance.  To  form 
a due  conception  of  its  extent,  it  must  be  understood,  that  the 
convolutions  of  the  brain  are  a sort  of  duplicatures,  susceptible 
of  extension  by  the  unfolding  of  two  contiguous  medullary  la- 
minae, which  form  its  base.  The  exterior  surface  of  the  brain, 
by  means  of  this  unfolding,  offers  then  some  relation  to  the  skin, 
a vast  nervous  expanse  every  where  covered  by  a sort  of  pulpy 
substance,  known  by  the  name  of  the  rete  mucosum  of  Mal- 
pighi. M.  Gall  compares  this  cutaneous  pulp  to  the  cineritious 
substance  which  forms  the  outer  part  of  the  brain,  and,  I must 
confess,  it  is  not  every  one  that  will  admit  the  analogy.  - How- 
ever, true  it  is,  that  the  brain  consists,  principally,  of  a mass  of 
ganglions,  that  it  produces  neither  the  elongated  medujla,  nor 
the  spinal  marrow;  that  this  last  may  be  considered  as  a series 
of  ganglions  united  together;  that  the  vertebral  nerves  arise  from 
the  grayish  pulp  of  which  the  spinal  marrow  is  full,  as  is  best 
seen  in  animals  without  a brain,  but  not  the  less  provided  with 
a spinal  marrow,  or  series  of  ganglions,  front  which  the  nerves 
arise.  The  ganglions,  or  rather  the  gray  substance  which  they 
alway  show,  produce  the  nervous  fibres,  and  thicken  the  nervous 
cords  that  pass  through  them. 

That  is  the  only  use  that  can  be  assigned  to  these  parts  of  the 
nervous  system;  for,  if  they  were  meant  to  withdrawn  from  the 
dominion  of  the  will,  the  parts  in  which  they  are  found,  why  do 
not  the  ganglions  of  the  vertebral  nerves  fulfil  the  same  function? 
All  these  nerves  communicate  by  reciprocal  anastomoses.  These 
communications  in  man,  are  equivalent  to  a real  continuity.  In 
truth,  the  brain  acts  upon  the  nerves  that  proceed  from  the  spinal 
marrow,  as  if  this  were  one  of  its  productions,  and  all  the  ner- 
vous fibres,  spread  through  the  different  organs,  had  an  extre- 
mity terminating  in  this  viscus. 

One  thing  well  worthy  of  attention,  and  on  which  no  anato- 


OE  SENSATIONS. 


369 

mist  has  dwelt,  is  that  the  brain  of  the  foetus,  and  of  the  child 
just  born,  appears  to  consist,  almost  entirely,  of  a cineritious 
pulp,  to  such  a degree  that  the  medullary  substance  is  difficult 
to  perceive  in  it.  Would  it  be  absurd  to  believe,  that  the  me- 
dullary part  of  the  brain  does  not  take  its  perfect  organization 
till  after  birth,  by  the  development  of  the  fasciculi  of  medul- 
lary fibres,  in  the  midst  of  these  masses  of  cineritious  substance, 
which  must  be  considered  as  the  common  source  from  which 
the  nerves  have  their  origin,  or,  to  use  the  language  of  Gall,  as 
the  uterus  which  gives  them  birth.  The  almost  total  inactivity, 
the  passive  state  of  the  brain  in  the  foetus,  makes  unnecessary 
there  the  existence  of  the  medullary  apparatus,  to  which  the 
most  important  operations  of  intelligence  seem  entrusted.  Its 
first  rudiments  are  found  in  the  foetus  at  its  full  time-  That 
fibro-me dullary  apparatus  will  be  strengthened  by  the  exercise 
of  thought,  as  the  muscles  are  seen  to  enlarge  and  perfect  their 
growth  by  the  effect  of  muscular  action. 

CXLIV.  Circulation  of  the  brain.  I have  said  that  the  blood, 
in  its  circular  course,  does  not  traverse  the  different  parts  of  the 
body  with  uniform  velocity:  that  there  are  partial  circulations 
in  the  midst  of  the  general  circulation.  In  no  organ  are  the 
laws,  to  which  this  function  is  subjected,  more  remarkably  mo- 
dified than  in  the  brain.  There  is  none  which  receives,  in  pro- 
portion to  its  bulk,  larger  arteries  and  more  in  number.  The  in- 
ternal carotid  and  vetebral  arteries,  as  we  may  satisfy  ourselves 
from  the  calculations  of  Haller,  carry  thither  a great  portion  of 
the  whole  quantity  of  blood  that  flows  along  the  aorta;  (from  a 
third  to  the  half). 

The  blood  which  goes  to  the  brain,  said  Boerhaave,  is  more 
aerated  than  that  which  is  distributed  to  the  other  parts:  the  ob- 
servation is  not  without  foundation.  Though  the  blood  which 
the  contractions  of  the  left  ventricle  send  into  the  vessels 
arising  from  the  arch  of  the  aorta,  does  not  undergo,  at  the 
place  of  this  curvature,  a mechanical  separation  carrying  its 
lighter  parts  towards  the  head;  it  is  not  less  true,  that  this 
blood,  just  passing  from  the  contact  of  the  air  in  the  lungs, 
possesses,  in  the  highest  degree,  all  the  peculiar  qualities  of 
arterial  blood.  So  great  a quantity  of  light,  red,  frothy  blood, 
impregnated  with  caloric  and  oxygen,  coming  upon  the  brain, 

3 A 


OF  SENSATIONS. 


370 

with  all  the  force  it  has  received  from  the  action  of  the  heart, 
would  unavoidably  have  deranged  its  soft  and  delicate  struc- 
ture, if  nature  had  not  multiplied  precautions  to  weaken  its 
impulse. 

The  fluid,  compelled  to  ascend  against  its  own  weight,  loses, 
from  that  alone,  a part  of  its  motion.  The  vertical  column  must 
strike  against  the  angular  curvature  which  the  internal  carotid 
takes  in  its  passage  along  the  osseous  canal  of  the  petrous  por- 
tion of  the  temporal  bone;  and  as  this  curvature,  supported  by 
hard  parts,  cannot  straighten  itself,  the  column  of  blood  is  vio- 
lently broken  and  turned  out  of  its  first  direction,  with  conside- 
rable loss  of  velocity. 

The  artery  immersed  in  the  blood  of  the  cavernous  sinus, 
as  it  comes  out  from  the  carotid  canal,  is  very  easy  dilated. 
Finally,  the  branches  into  which  it  parts,  on  reaching  the  base 
of  the  brain,  have  coats  exceedingly  thin,  and  so  weak  that  they 
collapse,  when  they  are  empty,  like  those  of  the  veins.  This 
weakness  of  the  cerebral  arteries,  explains  their  frequent  rup- 
tures, when  the  heart  sends  the  blood  into  them  too  violently; 
and  it  is  thus  that  the  most  part  of  sanguineous  apoplexies  are 
occasioned,  many  of  which,  however,  take  effect  without  rup- 
ture, and  by  the  mere  transudation  of  blood  through  the  coats 
of  the  arteries.  These  vessels,  like  the  branches  arising  from 
their  divisions,  are  lodged  in  the  depressions  with  which  the 
base  of  the  brain  is  furrowed,  and  do  not  enter  its  substance 
till  they  are  reduced  to  a state  of  extreme  tenuity,  by  the  fur- 
ther divisions  they  undergo  in  the  tissue  of  the  pia  mater. 

Notwithstanding  the  proximity  of  the  brain  to  the  heart,  the 
blood  reaches  it  then  with  an  exceedingly  slackened  motion:  it 
returns,  on  the  contrary,  with  a motion  progressively  accelera- 
ted. The  position  of  the  veins  at  the  upper  part  of  the  brain,  be- 
tween its  convex  surface  and  the  hollow  of  the  skull,  causes 
these  vessels,  gently  compressed  by  the  alternate  motions  of 
rising  and  falling  of  the  cerebral  mass,  to  disgorge  their  con- 
tents readily  into  the  membranous  reservoirs  of  the  dura  mater, 
known  by  the  name  of  sinuses.  These,  all  communicating  to- 
gether, offer  to  this  fluid  a sufiiciendy  large  receptacle,  from 
which  it  passes  into  the  great  jugular  vein,  which  is  to  carry  it 
again  into  the  general  course  of  the  circulation.  Not  only  is  the 


GF  SENSATIONS. 


571 

caliber  of  this  vein  considerable,  but  its  coats  too,  of  little  thick- 
ness, are  very  extensible;  so  much  so  that  it  acquires,  by  injec- 
tion, a caliber  superior  to  that  of  the  vense  cavse.  The  flowing 
of  the  blood  is  favoured  by  its  own  weight,  which  makes  a re- 
trograde course  very  diflicult.*  Thus,  to  sum  up  all  that  is  pe- 
culiar  in  the  cerebral  circulation,  the  brain  receives,  in  great 
quantity,  a blood  abounding  in  oxygen;  the  fluid  finds,  in  its 
course  thither,  many  obstacles  which  impede  and  slacken  its 
impulse,  whilst  all,  on  the  contrary,  favours  its  return  and  pre- 
vents venous  congestion.!  Let  me  observe,  to  conclude  what 
I have  to  say  on  the  circulation  of  the  brain,  that  of  the  eye  Is 
nearly  allied  to  it,  since  the  ophthalmic  artery  is  given  out  by  the 
internal  carotid,  and  the  ophthalmic  vein  empties  itself  into  the 
cavernous  sinus  of  the  dura  mater.  Accordingly,  the  redness  of 
the  conjunctiva,  the  prominence,  the  brightness,  the  moistness 
of  the  eyes,  indicate  a stronger  determination  of  the  blood  to- 
wards the  brain.  Thus  the  eyes  are  animated  at  the  approach 
of  apoplexy,  in  the  transport  of  a burning  fever,  during  delirium, 
a dangerous  symptom  of  malignant  or  ataxic  fevers.  On  this 
connexion  of  the  vessels  of  the  eye  and  brain,  depends  the 
lividity  of  the  conjunctiva,  whose  veins,  injected  with  a dark 
coloured  blood,  indicate  the  fulness  of  the  brain  in  the  gene- 
rality of  cases  of  suffocation. 

CXLV.  Of  the  connexion  between  the  action  of  the  brain  and 
that  of  the  heart.  It  is  possible,  as  was  done  by  Galen,  to  tie 
both  carotids,  in  a living  animal,  without  his  appearing  sensibly 
affected  by  it;  but  if,  as  has  never  yet  been  done,  both  the  ver- 
tebral arteries  are  tied,  the  animal  drops  instantly  and  dies  at 
the  end  of  a few  seconds.  To  perform  this  experiment,  it  is  ne- 
cessary, after  tying  the  carotid  arteries  of  a dog,  to  remove  the 
soft  parts  which  cover  the  side  of  the  neck,  then  with  needles, 
bent  in  a semi-circular  form,  passed  into  the  flesh  along  the 

* In  preventing  this  reflux,  there  is  no  use  of  valves,  which  the  jugular  vein 
is  entirely  without.  It  is  sufficiently  prevented,  by  the  direction  in  which  the 
Wood  flows,  and  the  extensibility  of  its  coats.  This  great  size  which  the  vein 
can  acquire,  would  have  made  useless  the  valvular  folds,  insufficient  to  stop 
the  canal,  in  that  great  augmentation  of  its  dimensions. 

! The  transverse  anastomoses  of  the  arteries,  at  the  base  of  the  brain,  are 
very  proper  for  distributing  the  blood,  in  equal  quantity,  to  all  parts  of  this 
viscus. 


OF  SENSATIONS. 


372 

sides  of  the  articulation  of  the  cervical  vertebrse,  to  apply  liga- 
tures to  the  arteries  which  ascend  along  their  transverse  pro- 
cesses. The  same  effect,  viz.  the  speedy  death  of  the  animal, 
is  produced  by  tying  the  ascending  aorta  tn  an  herbivorous 
quadruped. 

These  experiments,  which  have  been  repeated  a number  of 
times,  decidedly  prove  the  necessity  of  the  action  of  the  heart 
on  the  brain,  in  preserving  life.  But  how  does  this  action  ope- 
rate? Is  is  merely  mechanical?  Does  it  consist  solely  in  the  gen- 
tle pressure  which  the  arteries  of  the  brain  exert  on  the  sub- 
stance of  this  viscus;  or  is  it  merely  to  the  intercepted  arte- 
rial blood  which  the  contractions  of  the  heart  determine  towards 
the  brain,  that  death  is  to  be  attributed?  The  latter  opinion 
seems  to  be  the  most  probable;  for,  if,  the  moment  the  verte- 
brals  have  been  tied,  the  carotids  are  laid  open,  and  the  pipe  of 
a syringe  adapted  to  them,  and  any  fluid  whatever  is  then  in- 
jected with  a moderate  degree  of  force,  and  at  nearly  the  same 
intervals  as  those  of  the  circulation,  the  animal  will  not  be  re- 
stored to  life. 

The  heart  and  brain  are,  therefore,  united  to  each  other  by 
the  strictest  connexion;  the  continual  access  of  the  blood  flowing 
along  the  arteries  of  the  head  is,  therefore,  absolutely  necessary 
to  the  preservation  of  life;  if  intercepted,  for  one  moment,  the 
animal  is  infallibly  destroyed. 

The  energy  of  the  brain  appears,  in  general,  to  bear  a rela- 
tion to  the  quantity  of  arterial  blood  which  it  receives.  I know 
a literary  man,  who,  in  the  ardour  of  composition,  exhibits  all 
the  symptoms  of  a kind  of  brain  fever.  His  face  becomes  red 
and  animated,  his  eyes  sparkling;  the  carotids  pulsate  violently; 
thejugular  veins  are  swollen;  every  thing  indicates  that  the 
blood  is  carried  to  the  brain  with  an  impetus,  and  in  a quantity 
proportioned  to  its  degree  of  excitement.  It  is,  indeed,  only 
during  this  kind  of  erection  of  the  cerebral  organ,  that  his 
ideas  flow  without  effort,  and  that  his  fruitful  imagination 
traces,  at  pleasure,  the  most  beautiful  descriptions.  Nothing 
is  so  favourable  to  this  condition  as  remaining  long  in  a re- 
cumbent posture;  in  this  horizontal  posture,  the  determination 
of  the  fluids  towards  the  head  is  the  more  easy,  as  the  limbs, 
which  are  perfectly  quiescent,  do  not  divert  its  course.  He  can 


OF  SENSATIONS. 


373 

bring  on  this  state  by  fixing  his  attention  steadfastly  on  one  ob- 
ject. May  not  the  brain,  which  is  the  seat  of  this  intellectual 
action,  be  considered  as  a centre  of  fluxion;  and  may  not  the 
stimulus  of  the  mind  be  compared,  as  to  its  effects,  to  any  other 
stimulus,  chemical  or  mechanical? 

A young  man  of  a sanguineous  temperament,  subject  to  in- 
flammatory fevers  which  always  terminate  by  a profuse  bleed- 
ing at  the  nose,  experiences,  during  the  febrile  paroxysms,  a re- 
markable increase  of  his  intellectual  powers  and  of  the  activ  y 
of  his  imagination.  Authors  had  already  observed,  that  n.  . ,r- 
tain  febrile  affections,  patients  of  very  ordinary  powers  of  mind, 
would  sometimes  rise  to  ideas  which,  in  a state  of  health,  would 
have  exceeded  the  limits  of  their  conception.  May  we  not  ad- 
duce these  facts  in  opposition  to  the  theory  of  a celebrated 
physician,  who  considers  a diminution  of  the  energy  of  the 
brain  to  be  the  essential  character  of  fever? 

It  is  well  known,  that  the  difference  of  the  length  of  the  neck, 
and,  consequently,  the  greater  or  lesser  degree  of  vicinity  of  the 
heart  and  brain,  give  a tolerably  just  measure  of  the  intellect  of 
man,  and  of  the  instinct  of  the  lower  animals;  the  dispropor- 
tionate length  of  the  neck  has  ever  been  considered  as  the  em- 
blem of  stupidity. 

In  the  actual  state  of  our  knowledge,  is  it  possible  to  deter- 
mine in  what  manner  arterial  blood  acts  on  the  brain?  Are 
oxygen  or  caloric,  of  which  it  is  the  vehicle,  separated  from  it 
by  this  viscus,  so  as  to  become  the  principle  of  sensation  and 
emotion;  or  do  they  merely  preserve  it  in  the  degree  of  con- 
sistence necessary  to  the  exercise  of  its  functions?  What  is  to 
be  thought  of  the  opinion  of  those  chemists  who  consider  the 
brain  as  a mere  albuminous  mass,  concreted  by  oxygen,  and  of 
a consistence  varying  in  different  persons,  according  to  the  age, 
the  sex,  or  the  state  of  health  or  disease?  Any  answer  that  one 
might  give  to  these  premature  questions,  would  be  but  a simple 
conjecture,  to  which  it  would  be  difficult  to  give  any  degree  of 
probability. 

CXLVI.  Of  the  theory  of  Syncope.  If  we  consider  the  action 
of  the  heart  on  the  brain,  we  are  naturally  led  to  admit  its  ne- 
cessity to  the  maintenance  of  life,  and  to  deduce  from  its  mo- 
mentary suspension,  the  theory  of  syncope.  Several  authors 


OF  SENSATIONS. 


3T4 

have  attempted  to  explain  the  manner  in  which  their  proximate 
cause  operates,  but  as  not  one  of  them  has  gone  upon  fact»  as* 
certained  by  experience,  their  explanations  do  not  at  all  agree 
with  what  is  learnt  from  observing  the  phenomena  of  their 
diseases. 

To  satisfy  oneself  that  the  momentary  cessation  of  the  action 
of  the  heart  on  the  brain,  is  the  immediate  cause  of  syncope, 
one  need  but  read,  with  attention,  the  chapter  which  Cullen,  in 
his  work  on  the  practice  of  physic,  has  devoted  to  the  conside* 
ration  of  this  kind  of  affection.  It  will  be  readily  understood, 
that  their  occasional  causes,  the  varieties  of  which  determine 
their  different  kinds,  exist  in  the  heart  or  great  blood-vessels, 
or  act  on  the  epigastric  centre,  and  affect  the  brain  only  in  a 
secondary  manner.  Thus  the  kinds  of  syncope  occasioned  by 
aneurismal  dilatations  of  the  heart  and  great  vessels,  by  poly- 
pous concretions  formed  in  these  passages,  by  ossification  of 
their  parietes  or  of  their  valves,  evidently  depend  on  the  ex- 
treme debility,  or  on  the  entire  cessation  of  the  action  of  the 
heart  and  arteries.  Their  parietes,  ossified,  dilated,  adhering 
to  the  neighbouring  parts,  or  compressed  by  any  fluid  what- 
ever, no  longer  act  on  the  blood  with  sufficient  force,  or  else 
this  fluid  is  interrupted,  in  its  progress,  by  some  obstacle  with- 
in its  canal,  as  a polypous  concretion,  an  ossified  and  immove- 
able valve.  Cullen,  very  justly,  termed  these,  idiopathic  or  car- 
diac syncopes. 

To  the  above  may  be  added  plethoric  syncope,  depending  on 
a congestion  of  blood  in  the  cavities  of  the  heart:  the  contrac- 
tion of  this  organ  become  more  frequent;  it  struggles  to  part 
with  this  excess  of  blood,  which  is  injurious  to  the  performance 
of  its  functions;  but  to  this  unusual  excitement  by  which  the 
contractility  of  its  fibres  is  exhausted,  there  succeeds  a kind  of 
paralysis  necessarily  accompanied  by  syncope. 

One  may,  likewise,  include  the  fainting  attending  copious 
blood-letting;  the  rapid  detraction  of  a certain  quantity  of  the 
vivifying  principle  deprives  the  heart  of  the  stimulus  necessary 
to  keep  up  its  action.  The  same  effect  is  produced  by  drawing  off 
the  water  contained  in  the  abdomen,  in  ascites:  a considerable  a 
number  of  vessels  cease  to  be  compressed;  the  blood  which  they 
before  refused  to  transmit,  is  sent  to  them  in  profusion;  the 


OP  SENSATIONS. 


375 


quantity  sent  to  the  brain  by  the  heart  is  lessened,  in  the  same 
proportion,  and  becomes  insufficient  for  its  excitement.  Among 
the  syncopes,  called  idiopathic,  one  may  enumerate  those  oc= 
curring  in  the  last  stage  of  the  scurvy,  the  principal  character 
of  which  is,  an  excessive  debility  of  the  muscles  employed  in 
the  vital  functions,  and  involuntary  motion;  lastly,  we  may 
add  asphyxia  from  strangulation,  from  drowning,  and  from  the 
gases  unfit  for  respiration;  affections  in  which  the  blood  being 
deprived  of  the  principle  which  enables  it  to  determine  the 
contractions  of  the  heart,  the  circulation  becomes  interrupted. 
If  the  blood  loses,  by  slow  degrees,  its  stimulating  qualities, 
the  action  of  the  heart-  gradually  weakened,  impels  towards  the 
brain  a blood  which,  by  its  qualities,  partakes  of  the  nature  of 
venous  blood,  and  which,  like  it,  cannot  preserve  the  natural 
economy  of  the  brain.  It  was  thought,  that  by  injecting  a few 
bubbles  of  air  into  the  jugular  vein  of  a dog,  one  might  occa- 
sion in  the  animal  immediate  syncope,  and  that  it  was  even 
sufficient  to  deprive  it  of  life;  but  the  late  experiments  of  M. 
Nysten  have  proved,  that  the  atmospherical  air  produces  these 
bad  effects,  only  when  injected  in  a quantity  sufficient  to  dis- 
tend, in  excess,  the  cavities  of  the  heart,  or  when  by  being  in- 
jected into  the  arteries,  it  compresses  the  brain.  When  injected 
only  in  a small  quantity,  the  gas,  dissolved  in  the  venous  blood, 
is  conveyed  along  with  it  to  the  lungs,  and  is  thence  exhaled  in 
respiration. 

A second  class  of  occasional  causes  consists  of  those  which, 
by  acting  on  the  epigastric  centre,  determine,  by  sympathy,  a 
cessation  of  the  pulsations  of  the  heart  and  the  syncope  neces- 
sarily attending  this  cessation.  Such  are  the  violent  emotions  of 
the  soul;  terror,  an  excess  of  joy,  an  irresistible  aversion  to  cer- 
tain kinds  of  food,  the  dread  which  is  felt  on  the  unexpected 
sight  of  an  object,  the  disagreeable  impression  occasioned  by 
certain  odours,  &c.  In  all  these  cases,  there  is  felt  in  the  region 
of  the  diaphragm  an  inward  sensation  of  a certain  degree  of 
emotion.  From  the  solar  plexus  of  the  great  sympathetic  nerve, 
which,  according  to  the  general  opinion,  is  considered  as  the 
seat  of  this  sensation,  its  effects  extend  to  the  other  abdominal 
and  thoracic  plexuses.  The  heart,the  greater  part  of  whose  nerves 
arise  from  the  great  sympathetic,  is  particularly  affected  by  this 


OF  SENSATIONS. 


376 

sensation.  Its  action  is,  at  tinaes,  merely  disturbed  by  it,  and  at 
others  wholly  suspended.  The  pulse  becomes  insensible,  the 
countenance  pale,  the  extremities  cold,  and  syncope  ensues. 
This  is  the  course  of  things,  when  a narcotic  or  poisonous  sub- 
stance has  been  taken  into  the  stomach;  when  this  viscus  is 
much  debilitated  in  consequence  of  long  fasting,  or  when  it 
contains  indigestible  substances;  in  colic,  and  in  hysterical 
affections. 

This  last  class  of  occasional  causes  do  not  act  directly,  and 
produce  syncope  only  at  a distant  period;  but  the  result  is 
always  the  same.  It  happens,  in  all  these  cases,  that  as  the  arte- 
ries of  the  head  no  longer  receive  as  much  blood  as  in  health, 
the  brain  falls  into  a kind  of  collapse,  which  occasions  a mo- 
mentary cessation  of  the  intellectual  faculties,  of  the  vital  func- 
tions, and  of  voluntary  motion. 

Morgagni,  in  treating  of  diseases,  according  to  their  anatomi- 
cal order,  ranks  lypothymia  among  the  affections  of  the  chest; 
because  the  viscera  contained  in  that  cavity,  show  marks  of 
organic  affection,  in  persons  who,  during  life,  were  subject  to 
frequent  fainting. 

The  compression  of  the  brain,  by  a fluid  effused  on  the  dura 
mater,  in  wounds  of  the  head,  does  not  produce  real  syncope, 
but  rather  a state  of  stupor.  All  causes  acting  in  this  manner  on 
the  brain,  produce  comatose  and  even  apoplectic  affections. 
When  a man,  on  being  exasperated,  falls  into  a violent  and  sud- 
den fit  of  passion,  his  face  becomes  flushed,  and  he  is  affected 
with  vertigo  and  fainting.  There  is  no  loss  of  colour,  no  loss  of 
pulse;  the  latter,  on  the  contrary,  generally  beats  with  more 
force.  This  is  not  syncope,  but  the  first  stage  of  apoplexy,  oc- 
casioned by  the  mechanical  pressure  on  the  brain,  towards 
which  the  blood  is  carried  suddenly,  and  in  too  great  a quantity. 

I might  support  this  theory  of  syncope,  by  additional  proofs 
drawn  from  the  circumstances  which  favour  the  action  of  the 
causes  giving  rise  to  affections  of  this  kind.  For  instance,  syn- 
cope comes  on,  almost  always,  when  we  are  in  an  erect  posture, 
and  in  such  a case,  it  is  right  to  lay  the  patient  in  a horizontal 
posture.  Patients  debilitated  by  long  diseases,  faint  the  moment 
they  attempt  to  rise,  and  recover  on  returning  to  the  recumbent 
posture.  Now,  how  are  we  to  explain  this  effect  of  standing,  in 


OF  SENSATIONS. 


377 

persons  in  whom  the  mass  of  humours  is  much  impoverished, 
and  whose  organic  action  is  extremely  languid,  unless  by  the 
greater  difficulty  to  the  return  of  the  blood  from  the  more  de- 
pending parts,  and  on  the  difficulty  in  ascending  of  that  which 
the  contractions  of  the  heart  send  towards  the  head?  The  phe- 
nomena of  the  circulation  are,  under  such  circumstances,  more 
subject  to  the  laws  of  hydraulics,  than  when  the  body  is  in  a 
state  of  health;  the  living  solid  yields  more  easily  to  the  laws  of 
physics  and  mechanics,  and,  according  to  the  sublime  idea  of 
the  father  of  physic,  our  individual  nature  approaches  the  more 
to  universal  nature. 

CXLVII.  Of  the  motions  of  the  brain.  Are  the  alternate  mo- 
tions of  elevation  and  depression  seen,  when  the  brain  is  ex- 
posed, exclusively  isochronous  to  the  pulsations  of  the  heart  and 
arteries;  or  do  they  correspond,  at  the  same  time,  to  those  of 
respiration?  Such  is  the  physiological  problem  of  which  I am 
about  to  attempt  the  solution. 

Those  authors  who  admit  the  existence  of  motions  in  the 
dura  mater,  do  not  agree  as  to  the  cause  which  produces  them. 
Some,  and  among  others,  Willis  and  Baglivi,  thought  they  had 
discovered  muscular  fibres,  and  ascribed  these  motions  to  their 
action:  others,  as  Fallopius  and  Bauhinus,  attributed  these  mo- 
tions to  the  pulsations  of  the  arteries  of  that  membrane.  The 
dura  mater  possesses  no  contractile  power;  its  firm  adhesion  to 
the  inside  of  the  skull,  would,  besides,  prevent  any  such  motion. 
The  motion  observed  in  this  membrane  is  not  occasioned  by 
the  action  of  its  vessels;  for,  as  Lorry  observes,  the  arteries  of 
the  stomach,  of  the  intestines,  and  of  the  bladder,  do  not  com- 
municate any  motion  to  the  parietes  of  these  hollow  viscera, 
and  yet  in  number  and  size,  they  at  least  equal  the  menyngeal 
arteries. 

The  motion  observed  in  the  dura  mater  is  communicated  to 
it  by  the  cerebral  mass  which  this  membrane  covers;  and  this 
opinion  of  Galen,  adopted  by  the  greater  number  of  anatomists, 
has  been  placed  beyond  a doubt  by  the  experiments  of  Schlitting, 
of  Lamure,  Haller  and  Vicq-d’Azyr.  They  have  all  observed, 
that  on  removing  the  dura  mater,  the  brain  continued  to  rise 
and  fall;  and,  with  the  exception  of  Schlitting,  they  agreed  that 
the  brain,  absolutely  passive,  received  from  its  vessels  the  mo- 

3 B 


OF  SENSATIONS. 


378 

tions  in  which  the  dura  mater  partook:  but  are  these  motions 
communicated  by  the  arteries  or  by  the  cerebral  veins,  and  by 
the  sinuses  in  which  these  terminate?  or,  in  other  words,  are 
they  isochronous  to  the  beats  of  the  pulse,  or  to  the  contraction 
and  successive  dilatation  of  the  chest  during  respiration? 

Galen,  in  his  treatise  on  this  function,  says,  that  the  air  ad- 
mitted into  the  pulmonary  organ  distends  the  diaphragm,  and  is 
conveyed  along  the  vertebral  canal  into  the  skull.  According  to 
this  writer,  the  brain  rises  during  the  enlargement  of  the  chest, 
and  it  sinks,  on  the  contrary,  when  the  parietes  of  this  cavity 
are  brought  nearer  to  its  axis.  Schlitting,  in  a memoir  present- 
ed to  the  Academy  of  Sciences,  towards  the  middle  of  the  last 
century,  maintains  that  these  motions  take  place  in  a different 
order;  the  elevation  of  the  brain  corresponding  to  expiration, 
and  its  depression  to  inspiration.  Conceiving  that  he  has  deter- 
mined this  fact  by  a sufficient  number  of  experiments,  he  does 
not  enter  into  any  explanation,  and  concludes  his  inquiry,  by 
asking  whether  the  motions  of  the  brain  are  occasioned  by  the 
afflux  of  air,  or  of  blood  towards  that  organ. 

Haller  and  Lamure  attempted  to  answer  this  difficulty.  They 
both  performed  a number  of  experiments  on  living  animals,  ac- 
knowledged the  fact  observed  by  Schlitting,  and  explained  it  in 
the  following  manner.  As  well  at  this  last  anatomist,  Lamure 
believed  that  there  is  a vacuum  between  the  dura  and  pia  mater, 
by  means  of  which  the  motions  of  the  brain  might  always  be 
performed.  The  existence  of  such  a vacuum  is  disproved  by  the 
close  contact  of  the  membranes  between  which  it  is  supposed  to 
exist. 

During  expiration,  continues  Lamure,  the  parietes  of  the  chest 
close  on  themselves,  and  lessen  the  extent  of  this  cavity.  The 
lungs,  pressed  in  every  direction,  collapse;  the  curvature  of 
their  vessels  increases,  and  the  blood  flows  along  them  with 
difficulty.  The  heart  and  great  vessels  thus  compressed,  the 
blood  carried  by  the  upper  vena  cava  to  the  right  auricle,  cannot 
be  freely  poured  into  this  cavity,  which  empties  itself,  with  dif- 
ficulty, into  the  right  ventricle,  whose  blood  is  unable  to  pene- 
trate through  the  pulmonary  tissue.  On  the  other  hand,  as  the 
lungs  compress  the  vena  cava,  a regurgitation  takes  place  of  the 
blood  which  it  was  conveying  to  the  heart;  forced  back  along 


OF  SENSATIONS. 


379 

the  jugulars  and  vertebrals,  it  distends  these  vessels,  the  sinus 
of  the  dura  mater  which  empty  themselves  into  them,  and  the 
veins  of  the  brain  which  terminate  into  these  sinuses.  Their 
distention  accounts  for  the  elevation  of  the  cerebral  mass,  soon 
followed  by  depression,  when,  on  inspiration  succeeding  expi- 
ration, and  on  the  lungs  dilating,  the  blood  which  fills  the  right 
cavities  of  the  heart,  can  freely  penetrate  into  the  pulmonary 
substance,  and  make  way  for  that  which  the  vena  cava  is  bring- 
ing from  the  superior  parts  of  the  body. 

Haller  considered  this  reflux  as  very  difficult,  the  blood 
having  to  rise  against  its  own  gravity;  and  he  admitted  La- 
mure’s  explanation  only  in  the  forcible  acts  of  respiration,  as  in 
coughing,  laughing,  and  sneezing.  He  maintained  that,  in  a 
state  of  health,  there  is  to  be  observed  during  expiration  a mere 
stagnation  of  the  blood,  in  the  vessels  which  bring  it  from  the 
internal  parts  of  the  skull.  He  further  admits,  on  the  testimony 
of  a great  number  of  authors,  another  order  of  motions  depend- 
ing on  the  pulsations  of  its  arteries;  so  that,  according  to  Hal- 
ler, the  cerebral  mass  is  incessantly  affected  by  motions,  some 
of  which  depend  on  respiration,  while  the  others  are  quite  in- 
dependent of  it. 

Lastly,  according  to  Vicq-d’Azyr,  the  brain,  on  being  expos- 
ed, presents  a double  motion,  or  rather  two  kinds  of  motion 
from  without:  the  one  from  the  arteries,  and  which  is  least  re- 
markable, the  other  from  the  alternate  motions  of  respiration. 

CXLVIII.  This  opposition  between  authors  of  reputation, 
and  whose  theories  have  in  general  been  adopted,  induced  me 
to  repeat  the  experiments  which  each  of  them  brings  in  support 
of  his  own  opinion,  and  to  perform  further  experiments  on  this 
subject.  My  investigation  soon  convinced  me,  that  these  au- 
thors had  given  a statement  of  their  opinions,  and  not  of  the  fact 
itself.  In  fact,  the  alternate  motions  of  elevation  and  depression 
observed  in  the  brain,  are  isochronous  to  the  systole  and  dias- 
tole of  the  arteries  at  its  base.  The  elevation  of  the  brain  cor- 
responds to  the  dilatation  of  these  vessels,  its  depression  to  their 
contractions.  The  process  of  respiration  has  nothing  to  do  with 
this  phenomenon;  and  even  admitting  the  stagnation  or  the 
regurgitation  of  the  blood  in  the  jugular  veins,  the  arrangement 


380 


OF  SENSATIONS. 


of  the  veins  within  the  skull  is  such,  that  this  stagnation  or  re- 
flux could  not  produce  alternate  motions  of  the  cerebral  mass. 

The  brain  receives  its  arteries  from  the  carotids  and  verte- 
brals,  after  they  have  entered  the  skull;  the  former  along  the 
carotid  canals,  the  latter  through  the  foramen  magnum  of  the  oc- 
cipital bone.  It  would  be  useless  to  describe  their  numerous 
divisions,  their  frequent  anastomoses,  the  arterial  circle,  or  ra- 
ther polygon,  formed  by  these  anastomoses,  and  by  means  of 
which  the  carotid  and  vertebral  arteries  communicate  together, 
by  the  side  of  the  sella  turcica.  Haller  has  given  a very  correct 
view,  and  an  excellent  description  of  this  part.*  The  account  of 
the  internal  carotid  artery  published  by  that  great  anatomist  is, 
according  to  Vicq-d’Azyr,  a chief-d’oeuvre  of  learning  and  pre- 
cision; the  same  encomium  might  be  bestowed  on  the  latter, 
who  gave  a superb  drawing  of  the  same  part.  I shall  content 
myself  with  observing,  that  the  principal  arterial  trunks  going 
to  the  brain,  are  situated  at  the  base  of  this  viscus;  that  the 
branches  into  which  these  trunks  divide,  and  the  subdivisions  of 
these  branches,  are,  likewise,  lodged  at  its  base  in  a number  of 
depressions;  and  that,  in  the  last  place,  the  arteries  of  the  brain 
do  not  penetrate  into  its  substance,  till  after  they  have  undergone 
in  the  tissue  of  the  pia  mater,  which  appears  completely  vascu- 
lar, very  minute  subdivisions. 

The  vessels  which  return  the  portion  of  blood  which  has  not 
been  employed  in  the  nutrition  and  growth  of  the  brain,  are,  on 
the  contrary,  situated  towards  its  upper  part,  between  its  con- 
vex surface  and  the  arch  of  the  cranium;  each  convolution  con- 
tains a great  vein,  which  opens  into  the  superior  longitudinal 
sinus.  The  vena  Galeni,  which  deposits  into  the  sinus  the  blood 
brought  from  the  choroid  plexus;  small  veins  which  open  into 
the  cavernous  sinuses;  others,  likewise,  very  minute,  which 
passing  through  the  formina  in  the  alee  majores  of  the  sphenoid 
bone,  contribute  to  form  the  venous  plexus  of  the  zygomatic 
fossae,  are  the  only  exceptions  to  this  general  rule. 

This  being  laid  down  on  the  arrangement  of  the  arteries  and 
veins,  let  us  examine  what  will  be  the  effect  of  their  action  with 
regard  to  this  viscus. 

* Fasciculi  anatomici.  F.  7.  tab.  1. 


OF  SENSATIONS. 


381 


The  contractions  of  the  heart  propel  the  blood  into  the  arterial 
tubes,  which  experience,  especially  at  the  place  of  their  curva- 
tures, a manifest  displacement  at  the  time  of  their  dilatation. 
All  the  arteries  situated  at  the  base  of  the  brain,  experience 
both  these  effects  at  once.  Their  united  efforts  communicate  to 
it  a motion  of  elevation,  succeeded  by  depression,  when,  by  their 
contraction,  they  re-act  on  the  blood  which  fills  them. 

These  motions  take  place  only  as  long  as  the  skull  remains 
entire;  this  cavity  is  too  accurately  filled,  and  there  is  no  void 
space  between  the  membranes  of  the  brain.  Lorry,  who,  with 
good  reason,  denied  the  existence  of  such  a space,  committed 
an  equally  serious  anatomical  mistake  in  asserting,  that  as  no 
motion  could  take  place  on  account  of  the  state  of  fulness  of 
the  skull,  it  was  effected  in  the  ventricles,  which  he  considers 
as  real  cavities,  but  which,  as  Haller  has  shown,  are,  when  in  a 
natural  state,  merely  surfaces  in  contact.  No  motion  actually 
takes  place,  except  in  those  cases  in  which  there  is  a loss  of 
substance  in  the  parietes  of  the  skull. 

It  is  easy  to  conceive,  however,  that  the  brain,  which  is  soft 
and  of  weak  consistence,  yields  to  the  gentle  pressure  of  its 
arterial  vessels.  Does  not  this  continued  action  of  the  heart  on 
the  brain,  explain,  in  a satisfactory  manner,  the  remarkable  sym- 
pathy between  those  two  organs,  linked  by  such  close  connec- 
tions? It  is,  besides,  of  very  manifest  utility,  and  connected  with 
the  return  of  the  blood,  distributed  to  the  cerebral  mass  and  its 
envelopes.  T^e  veins  which  bring  it  back,  alternately  compress- 
ed against  the  arch  of  the  skull,  empty  themselves  more  easily 
into  the  sinuses  of  the  dura  mater,  towards  which  their  course 
is  retrograde,  and  unfavourable  to  the  circulation  of  the  blood 
which  they  pour  into  them. 

When  any  thing  impedes  the  free  passage  of  the  blood  through 
the  lungs,  it  stagnates  in  the  right  cavities  of  the  heart;  the  su- 
perior vena  cava,  the  internal  jugulars,  and  consequently  the 
sinuses  of  the  dura  mater,  and  the  veins  of  the  brain  which  ter- 
minate in  them,  are  gradually  distended;  and  if  this  dilatation 
were  carried  to  a certain  degree,  the  veins  of  the  brain,  placed 
between  it  and  the  arch  of  the  skull,  would  tend  to  depress  it 
towards  the  base  of  that  cavity.  If  this  dilatation,  at  first  slight, 
were  carried  beyond  the  extensibility  of  these  vessels,  their  rup- 


382 


OF  SENSATIONS. 


ture  would  occasion  fatal  effusions.  It  is  in  this  manner  that 
some  authors  have  explained  sanguineous  apoplexy. 

It  will  be  objected,  perhaps,  that  many  of  the  sinuses  of  the 
dura  mater  are  at  the  base  of  the  skull,  and  that,  consequently, 
their  dilatation  must  tend  to  raise  the  cerebral  mass. 

But  the  greater  part  of  these  sinuses  are  connected  only  with 
the  cerebellum  and  the  medulla  oblongata,  of  which  it  has  not 
yet  been  possible  to  ascertain  the  motions.  These  sinuses  are 
almost  all  lodged  in  the  edges  of  the  falx  and  of  the  tentorium 
cerebelli.  The  cavernous  sinus  in  which  the  ophthalmic  vein 
disgorges  itself,  the  communicating  sinuses  which  allow  the 
blood  of  one  of  these  sinuses  to  pass  into  the  other,  are  too 
insignificant  to  produce  a raising  of  the  cerebral  mass.  Lastly, 
the  resistance  of  their  parietes,  formed  chiefly  by  the  dura  mater, 
must  set  strait  bounds  to  their  dilatation;  the  spungy  tissue 
which  fills  the  interior  of  the  cavernous  sinuses,  still  makes  this 
dilatation  and  the  reflux  of  the  blood  more  difficult. 

CXLIX.  It  is  not  enough  to  prove,  by  reasons  drawn  from 
the  disposition  of  parts,  that  the  motions  of  the  brain  are  com- 
municated to  it  by  the  collection  of  arteries  at  its  base;  the  fact 
must  yet  be  established  upon  observation,  and  placed  beyond 
doubt  by  positive  experiments.  The  following  are  what  I have 
attempted  for  this  purpose: 

A.  I have  first  repeated  the  observation  of  some  authors,  and 
ascertained,  as  they  did,  that  the  pulsations  felt  on  placing  the 
finger  on  the  fontanels  of  the  skulls  of  new-born  infants,  corres- 
pond perfectly  to  the  beatings  of  the  heart  and  arteries. 

B.  A patient,  trepanned  for  fracture,  with  effusion  on  the 
dura  mater,  enabled  me  to  see  the  brain,  alternately  rising  and 
falling.  The  rising  corresponded  with  the  diastole,  the  falling 
with  the  systole  of  the  arteries. 

C.  Two  dogs,  trepanned,  exhibited  the  same  phenomenon, 
in  the  same  relation  to  the  dilatation  and  contraction  of  the 
arteries. 

D.  I removed  carefully  the  arch  of  the  skull,  on  the  body  of 
an  adult.  The  dura  mater,  disengaged  from  its  adhesions  to  the 
bones  which  it  lines,  was  preserved  perfectly  untouched.  I after- 
wards laid  bare  the  main  carotids,  and  injected  them  with  water. 
At  every  stroke  of  the  piston,  the  brain  showed  a very  sensible 


OF  SENSATIONS. 


383 

motion  of  rising,  especially  when  the  injection  was  forced  at 
once  along  the  two  carotids. 

E.  I have  injected  the  internal  jugular  veins.  The  cerebral 
mass  remained  motionless.  Only  the  veins  of  the  brain,  the  si- 
nuses of  the  dura  mater  dilated.  The  injection  having  been  kept 
up  for  some  time,  there  resulted  from  it  a slight  swelling  of  the 
brain:  when  driven  with  more  force,  some  of  the  veins  burst  and 
the  liquor  flowed  out.  The  same  injection  being  made  with 
water  strongly  reddened,  the  surface  of  the  brain  became  colour- 
ed with  an  intense  red.  To  see  clearly  this  effect,  you  ought, 
after  removing  the  arch  of  the  skull,  to  divide  on  each  side  the 
dura  mater,  on  a level  with  the  circular  incision  of  the  skull, 
then  turn  back  the  flaps  towards  the  upper  longitudinal  sinus. 

F.  The  internal  jugular  veins  having  been  laid  open  while  the 
injection  was  forced  along  the  main  carotids,  each  time  the  pis- 
ton was  pushed  forward,  the  venous  blood  flowed  with  the 
greatest  impetus;  a clear  proof  of  the  manifest  influence  of  the 
motions  of  the  brain  on  the  course  of  the  blood  in  its  veins,  and 
in  the  sinuses  of  the  dura  mater.  This  experiment  had  been 
already  performed  by  other  anatomists,  and  amongst  others  by 
Ruysch,  with  a view  of  proving  the  immediate  communication 
between  the  arteries  and  veins.  This  communication,  which  is, 
at  present,  universally  acknowledged,  may  be  proved  by  other 
facts.  This  one  is  evidently  any  thing  but  conclusive. 

G.  In  a trepanned  dog,  I tied  successively  the  two  carotids. 
The  motions  of  the  brain  abated,  but  did  not  cease.  The  anas- 
tomoses of  the  vertebrals,  with  the  branches  of  the  carotids, 
account  for  this  phenomenon. 

H.  I took  a rabbit,  a gentle  creature,  easy  to  confine,  and 
very  well  adapted  for  difficult  experiments:  after  lying  bare  the 
brain,  and  observing  that  its  motions  were  simultaneous  to  the 
beats  of  the  heart,  I tied  the  trunk  of  the  ascending  aorta:  the 
moment  the  blood  ceased  rising  to  the  head,  the  brain  ceased 
moving,  and  the  animal  died, 

I.  The  tying  of  the  internal  jugular  veins,  did  not  stop  the 
motions  of  the  brain;  but  its  veins  dilated,  and  its  surface,  bared 
by  the  removal  of  a flap  of  the  dura  mater,  was  sensibly  redder 
than  in  the  natural  state.  The  dog  became  aflected  with  stupor, 
and  expired  in  convulsions. 


384 


OF  SENSATIONS. 


The  opening  of  these  veins' did  not  hinder  the  continuance  of 
the  motions;  they  grew  fainter  only  when  the  animal  was  weak- 
ened by  loss  of  blood. 

K.  The  opening  of  the  superior  longitudinal  sinus,  the  only 
one  that  could  easily  be  opened,  did  not  weaken  the  motions  of 
the  brain.  It  is  observed  that  the  blood  flows  out  more  freely 
from  it  during  the  elevation. 

L.  The  compression  of  the  thorax,  on  human  bodies,  pro- 
duces but  a slight  reflux  in  the  jugular  veins,  especially  if, 
during  this  compression,  the  trunk  is  kept  raised.  The  reflux 
is  greater  when  the  trunk  is  laid  flat. 

These  experiments  might  be  varied  and  multiplied;  if,  for 
instance,  the  injection  were  thrown,  at  once,  along  the  vertebral 
arteries,  and  the  internal  carotids:  but  those  I have  stated  are 
sufficient  for  my  purpose. 

Since  the  first  publication  of  this  enquiry  in  the  Memoirs  of 
the  Medical  Society,*  I have  had  many  opportunities  of  repeat- 
ing the  observations  and  experiments,  which  serve  as  a founda- 
tion to  the  theory  there  detailed.  Among  the  facts  which  con- 
firm this  theory,  there  is  one  that  appears  to  me  worth  stating: 
it  would  be  sufficient  by  itself,  if  it  were  possible  to  establish  a 
theory  on  the  observation  of  a single  fact.  A woman,  about  fifty 
years  of  age,  had  an  extensive  carious  affection  of  the  skull;  the 
left  parietal  bone  was  destroyed,  in  the  greatest  part  of  its  ex- 
tent, and  left  uncovered  a pretty  considerable  portion  of  the 
dura  mater.  Nothing  was  easier  than  to  ascertain  the  existence 
of  a complete  correspondence  between  the  motions  of  the  brain 
and  the  beats  of  the  pulse.  I desired  the  patient  to  cough,  to 
suspend  her  respiration  suddenly;  the  motions  continued  in  the 
same  relation  to  each  other;  when  she  coughed,  the  head  was 
shaken,  and  the  general  concussion,  in  which  the  brain  partook, 
might  have  been  mistaken  by  a prejudiced  observer,  for  the 
proper  motions  of  that  organ,  and  depending  on  the  reflux  of 
blood  in  the  veins. 

In  experiments  on  dogs,  the  same  motion  takes  place  when 
the  animal  barks;  but  it  is  easy  to  perceive,  that  the  concussion 
affecting  the  brain  is  experienced  by  the  whole  body,  and  that 

* M6moires  de  la  Society  M6diaale  de  Paris,  an  VII.  troUeme  annee,  pagpe 
197,  et  suiv. 


OF  SENSATIONS. 


385 


the  effort  of  expiration,  in  barking,  causes  a concussion  more 
or  less  violent. 

The  patient,  mentioned  in  the  preceding  observation,  died 
about  a month  after  I came  to  the  Hospital  of  St.  Louis,  in 
which  she  had  been  for  a considerable  length  of  time.  On  open- 
ing the  body,  the  left  lobe  of  the  brain  was  found  softened  and 
in  a kind  of  putrid  state;  the  ichor  which  was  formed,  in  consi- 
derable quantity,  flowed  outwardly,  by  a fistulous  opening  in 
the  dura  mater,  whose  tissue  was  rather  thickened. 

CL.  The  slight  consistence  of  the  brain,  which  Lorry  con- 
siders as  favourable  to  the  communication  of  the  motion  which 
its  arteries  impart  to  it,  appears  to  me  to  be  against  this  trans- 
mission. In  fact,  the  dilated  vessels  not  being  able  to  depress 
the  base  of  the  skull  on  which  they  rest,  make  their  eflEprt 
against  the  cerebral  mass,  and  raise  it  the  more  easily  (the 
arch  of  the  skull  being  removed)  from  its  presenting  a certain 
resistance.  If  the  brain  were  too  soft,  the  artery  would  merely 
swell  into  it,  and  would  not  lift  it.  To  satisfy  one’s  self  of  this 
truth,  one  need  only  observe  what  happens  when  the  posterior 
part  of  the  knee  rests  on  a pillow,  or  on  any  thing  of  the  same 
sort;  then,  the  motions  which  the  popliteal  artery  impresses  on 
the  limb,  are  but  little  apparent;  but  they  become  very  visible 
if  the  ham  rests  on  any  thing  that  resists  the  action;  on  the  other 
knee,  for  instance:  then  the  artery,  which  cannot  depress  it, 
exerts  its  whole  action  in  raising  the  lower  extremity,  which  it 
does  the  more  easily,  from  acting  against  a bony,  resisting,  and 
hard  part.  This  experiment  completely  invalidates  the  opinion 
of  Lorry.  The  want  of  analogy  will  not  be  objected:  it  will  not 
be  said  that  the  brain  is  heavier  than  the  lower  extremity,  nor 
that  the  sum  of  the  calibers  of  the  internal  carotid  and  the  ver- 
tebral arteries,  is  not  greater  than  that  of  the  popliteal  artery. 

This  continual  tendency  of  the  brain  to  rise,  produces  in  the 
end,  on  the  bones  of  the  skull  which  resist  this  motion,  very 
marked  effects.  Thus,  the  interior  surface  of  these  bones, 
smooth,  in  early  life,  becomes  furrowed  with  depressions,  the 
deeper  as  we  advance  in  age.  The  digital  depressions  and  the 
mammillary  processes,  corresponding  to  the  convolutions  and 
windings  of  the  brain,  are  very' evidently  the  result  of  its  ac- 
tion OB  the  enclosing  parietes.  Sometimes  it  happens  that,  at  a 

3 C 


38'6 


OF  SENSATIONS. 


very  advanced  age,  the  bones  of  the  skull  are  so  thinned  by  this 
internal  action,  that  the  pulsations  of  the  brain  become  percep* 
tible  through  the  hairy  scalp. 

No  doubt,  the  same  cause  hastens  the  destruction  of  the  skull 
by  the  fungous  tumours  of  the  dura  mater.  The  effort  from  ex- 
pansion of  the  tumour,  which  develops  itself,  is  further  added, 
and  makes  the  waste  of  the  bones  more  rapid.  At  the  end  of  a 
few  months,  the  tumour  projects  outwardly,  with  pulsations 
plainly  simultaneous  to  the  beatings  of  the  pulse,  as  Louis  obr 
serves  in  a memoir  inserted  among  those  of  the  Academy  of 
Surgery. 

I have  shown  (CXLVIII.)  that  the  disposition  of  the  veins 
of  the  brain  and  of  the  sinuses  of  the  dura  mater  was  adverse  to 
the  action  ascribed  to  them  on  this  viscus.  Experiment  (E.  L.) 
shows  that  the  stagnation  of  the  blood,  or  even  its  regurgita- 
tion, could  produce  only  a slow  and  gradual  distention  of  the 
sinuses  of  the  dura  mater,  and  veins  terminating  in  it  with  a 
slight  turgescence  of  the  cerebral  mass,  if  the  cause,  producing 
the  stagnation  of  the  blood  or  its  reflux,  prolonged  its  action  to 
a partial  destruction  of  the  skull. 

Lastly,  the  alternate  motions  of  the  brain,  said  to  correspond 
to  those  of  respiration,  ought  to  be  to  the  beats  of  the  pulse,  in 
the  ordinary  ratio  of  1 to  5.  On  the  contrary,  it  is  easy  to  sa- 
tisfy one’s  self  that  these  motions  are  in  an  inverse  ratio,  and 
perfectly  simultaneous  to  the  pulsations  of  the  heart  and  arteries. 

The  results  of  the  experiments  I have  stated  in  that  memoir, 
compared  to  those  obtained  by  justly  celebrated  inquirers,  are 
too  remarkably  different  not  to  have  induced  me  to  make  some 
attempt  at  investigating  the  cause  of  our  disagreement.  For 
that  purpose,  I thought  it  necessary  to  examine  scrupulously 
all  the  circumstances. 

The  work  of  Lamure  contains  anatomical  errors,  which  throw 
suspicions  upon  his  accuracy.  Haller  did  not  himself  make  the 
experiments  of  which  he  speaks,  in  treating  of  the  influence  of 
respiration  on  the  circulation  of  venous  blood.  This  article  is 
drawn  from  a thesis  defended  at  Gottingen  by  one  of  his  dis- 
ciples. Lastly,  Vicq-d’Azyr  attempted  no  confirming  experi- 
ment, and  seems  to  have  had  in  view  only  the  reconciling  all 
opinions. 


OF  SENSATIONS. 


387 


No  one  of  these  anatomists  has  distinguished  the  motions  of 
elevation  impressed  on  the  cerebral  mass  by  the  impulse  of  its 
arteries,  from  the  swelling  of  the  sinuses  of  the  dura  mater,  of 
the  veins  distributed  to  it,  and  from  the  tumefaction  of  the 
brain  which  may  be  caused  by  difficult  respiration.  This  mis- 
take would  be  the  more  easy,  as  animals  tortured  by  the  knife 
of  the  anatomist,  breathe  painfull)'^,  convulsively,  and  at  shorter 
intervals  than  in  their  natural  state.  Schlitting,  the  first  author 
of  these  experiments,  appears  especially  to  have  confounded  the 
motion  of  rising,  the  real  displacement  of  the  brain,  with  the 
turgescence  of  this  viscus.  At  every  expiration,  he  says,  I have 
seen  the  brain  rise,  that  is  to  say,  swell;  and  at  every  inspiration 
I have  seen  it  fall,  that  is  to  say,  collapse. 

“ Toties  animadverti  perspicue — in  omni  expiratione^  cere- 
brum universum  ascendere^  id  est  intumescere;  at  que  in  qudvis 
inspiratione  illud  descendere^  id  eat  detumescere?’’ 

We  may,  therefore,  consider  as  a truth  strictly  demonstrated 
by  observation,  experiment,  and  reasoning,  the  following  pro- 
position:— 

The  motions  observable  in  the  brain^  when  laid  bare^  are  im- 
parted to  it  solely  by  the  pulsations  of  the  arteries  at  its  base^  and 
are  perfectly  simultaneous  to  the  pulsations  of  these  vessels:  fur- 
ther^ the  refiux  and  stagnation  of  the  venous  bloody  are  able  to 
swell  its  substance. 

CLI.  Action  of  the  nerves  and  brain.  It  is  undoubtedly,  as 
Vicq-d’Azyr  has  said,  by  a motion  of  some  sort  that  the  nerves 
act.  Setting  out  from  this  simple  idea,  one  may  admit  several 
kinds  of  nervous  motions,  the  one  operating  from  the  circum- 
ference to  the  centre,  (it  is  the  motion  of  sensation  which  we  are 
about  more  particularly  to  study  in  this  paragraph;)  the  other, 
acting  from  the  centre  to  the  circumference,  and  this  motion, 
produced  by  the  will,  determines  the  action  of  the  muscular 
organs,  &c. 

In  what  manner  are  the  impressions  produced  on  the  senses 
by  the  bodies  which  surround  us,  transmitted,  along  the  nerves, 
to  the  brain?  Is  it  through  the  intervention  of  a very  subtle  fluid; 
or  can  the  nerves,  as  has  been  stated  by  some  physiologists,  be 
considered  as  vibrating  cords?  This  last  idea  is  so  absurd,  that 
one  cannot  help  wondering  it  should  so  long  have  been  in 


388 


OP  SENSATIONS. 


vogue.  A cord,  that  it  may  vibrate,  must  be  in  a state  of  ten- 
sion, along  the  whole  of  its  length,  and  fixed  at  both  extre- 
mities. The  nerves  are  not  in  a state  of  tension;  their  extre- 
mities, in  no  degree  fixed,  approach  towards  each  other  or  re- 
cede according  to  the  difference  of  position,  the  tension,  the 
turgescence,  the  fulness  or  collapse  of  parts,  and  vary  con- 
stantly in  their  distance  from  each  other.  Besides,  the  nervous 
cords,  situated  between  pulps,  at  their  origin,  and  at  their  ter- 
mination, cannot  be  extended  between  these  two  points.  The 
nervous  fibre  is  the  softest,  the  least  elastic  of  all  the  animal 
fibres;  when  a nerve  is  divided,  its  two  extremities,  far  from 
receding  by  contracting,  project,  on  the  contrary,  beyond  each 
other;  the  point  of  section  shows  a number  of  small  granula- 
tions of  medullary  and  nervous  substance,  which  flows  through 
its  minute  membranous  canals.  Surrounded  by  parts  to  which 
they  are,  to  a certain  degree,  united,  the  nerves  could  not 
vibrate.  Lastly,  admitting  the  possibility  of  their  being  capa- 
ble of  vibrating,  the  vibration  of  a single  filament  ought  to 
bring  on  that  of  all  the  rest,  and  carry  confusion  and  disorder 
in  every  motion  and  sensation. 

It  is  much  more  probable  that  the  nerves  act  by  means  of  a 
subtle,  invisible,  and  impalpable  fluid,  to  which  the  ancients 
gave  the  name  of  animal  spirits;  this  fluid,  unknown  in  its  na- 
ture, and  to  be  judged  of  only  by  its  effects,  must  be  wonder- 
fully minute,  since  it  eludes  all  our  means  of  investigation. 
Does  it  entirely  proceed  from  the  brain,  or  is  it  equally  se- 
creted by  the  membranous  envelopes  of  each  nervous  filament? 
( Neurilemes,  Reil.)  To  say  the  truth,  one  can  bring  no  other 
proof  of  the  existence  of  a nervous  fluid,  but  the  facility  with 
which,  by  means  of  it,  we  are  enabled  to  explain  the  various 
phenomena  of  sensation,  and  its  utility  in  explaining  these 
phenomena.  These  proofs,  however,  may  not  appear  com- 
pletely satisfactory  to  those  who  are  verj'  strict,  and  who  do 
not  consider  as  proved  what  is  merely  probable. 

Among  the  constituent  principles  of  the  atmosphere,  there 
are  generally  diffused  several  fluids,  such  as  the  magnetic  and 
electric  fluids.  Might  not  these  fluids,  on  entering  with  the  air 
into  the  lungs,  combine  with  the  arterial  blood,  and  be  convey- 
ed, by  means  of  it,  to  the  brain  or  to  the  other  organs?  Does 


OF  SENSATIONS, 


389 


not  the  vital  action  impart  to  them  new  qualities,  by  making 
them  undergo  unknown  combinations?  Do  caloric  and  oxygen 
enter  into  these  combinations  which  endow  fluids  with  a certain 
vitality,  and  produce  on  them  important  changes,  and  which 
are  not  understood?^  Have  not  these  conjectures  acquired  a 
certain  degree  of  probability,  since  the  analogy  of  galvanism 
to  electricity,  at  first  supposed  by  the  author  of  this  discovery, 
has  been  confirmed  by  the  very  curious  experiments  of  Volta, 
repeated,  commented,  and  explained  by  all  the  natural  philo- 
sophers of  the  present  day,  in  Europe.f 

The  action  of  the  nervous  fluid  takes  place  from  the  extre- 
mity of  nerves  towards  the  brain,  so  as  to  produce  the  pheno- 
mena of  sensation;  for,  when  the  nerves  are  tied,  the  parts  be- 
low the  ligature  lose  the  power  of  sensation,  while,  as  will  be 
seen  in  the  proper  place,  this  action  is  propagated  from  the 
brain  towards  the  nervous  extremities,  and  from  the  centre  to 
the  circumferenec,  in  producing  motions  of  every  kind.  This 
double  current,  in  contrary  directions,  may  take  place  in  the 
same  nerves,  and  it  is  not  necessary  to  arrange  the  nerves  into 
two  classes  of  sensation  and  of  motion. 

All  the  impressions  received  by  the  organs  of  sense,  and  by 
the  sentient  extremities  of  nerves,  are  transmitted  to  the  cere- 
bral mass.  The  brain  is,  therefore,  the  centre  of  animal  life;  all 
sensations  are  carried  to  it;  it  is  the  spring  of  all  voluntary  mo- 
tion; this  centre  is  to  the  functions  of  relation,  as  the  heart  to 
the  functions  of  nutrition.  One  may  say  of  the  brain,  as  of  the 
heart,  omnibus  dat  et  ab  omnibus  accipit.  It  receives  from  all, 
and  gives  to  all. 

The  existence  of  a centre,  to  which  all  the  sensations  are  car- 
ried, and  from  which  all  motions  spring,  is  necessary  to  the 
unity  of  a thinking  being,  and  to  the  harmony  of  the  intellectual 
functions.  But  is  this  seat  of  the  principle  of  motion  and  of  sensa- 
tion, circumscribed  within  the  narrow  limits  of  a mathematical 

* Were  it  not  for  these  changes,  electricity,  magnetism,  and  galvanism, 
would  suffice  to  restore  life  to  an  animal  recently  dead. 

f Galvanism,  as  yet,  has  not  realized  the  expectations,of  physiologists- 
Chemistry  has  derived  the  greatest  advantage  from  it. — It  is,  at  present, 
with  M.  M.  Davy,  Thenard  and  Gay-Lussac,  the  most  powerful  agent  in  the 
analysis  of  certain  bodies . 


390 


OP  SENSATIONS. 


point?  or  rather,  should  it  not  be  considered  as  diffused  over 
nearly  the  whole  brain?  The  latter  appears  to  me  the  more  pro- 
bable opinion;  where  it  otherwise,  what  could  by  the  use  of  those 
divisions  of  the  organ  into  several  internal  cavities?  What  could 
be  the  use  of  those  prominences,  all  varying  in  their  form,  and 
of  the  arrangement  of  the  two  substances  which  enter  into  their 
structure?  We  may  conjecture,  with  considerable  probability, 
that  each  perception,  each  class  of  ideas,  each  faculty,  is  assign- 
ed to  some  peculiar  part  of  the  brain.  It  is,  indeed,  impossible 
to  determine  the  peculiar  functions  of  each  part  of  the  organ;  to 
say  what  purpose  is  served  by  the  ventricles,  what  is  the  use  of 
the  commissures,  what  takes  place  in  the  peduncles;  but  it  is 
impossible  to  study  an  arrangement  of  such  combination,  and  to 
believe  that  it  is  without  design;  and  that  this  division  of  the 
cerebral  mass  into  so  many  parts,  so  distinct,  and  of  such  vari- 
ous forms,  is  not  relative  to  the  different  functions  which  each 
has  to  fill  in'the  process  of  thought.  That  ingenious  comparison, 
mentioned  in  the  panegyric  of  Mery,  by  Fontenelle,  is  ver}'^  ap- 
plicable in  the  brain.  “ We  anatomists,”  he  once  said  to  me, 
“ are  like  the  porters  in  Paris,  who  are  acquainted  with  the  nar- 
rowest and  most  distant  streets,  but  who  know  nothing  of  what 
takes  place  in  the  houses.”  What  then  are  we  to  think  of  the 
system  of  Gall,  and  of  his  division  of  the  outside  of  the  skull 
into  several  compartments,  which,  according  to  the  depression 
or  projection  of  the  osseous  case,  indicate  the  absence  or  the 
presence  of  certain  faculties,  moral  or  intellectual?  I cannot 
help  thinking,  that  this  physiological  doctrine  of  the  functions  of 
the  brain,  resting  on  too  few  well  observed  facts,  is  frivolous; 
while  his  anatomical  discoveries  on  the  anatomy  of  this  organ, 
and  on  the  nervous  system,  are  of  the  highest  importance,  and 
well  founded. 

CLII.  Analysis  of  the  Understanding.  In  vain  were  the  or- 
gans of  sense  laid  open  to  all  impressions  of  surrounding  objects; 
in  vain  were  their  nerves  fitted  for  their  transmission:  these  im- 
pressions were^us  as  if  they  had  never  been,  were  there  not 
provided  a seat  of  consciousness  in  the  brain.  For  it  is  there 
that  every  sensation  is  felt;  light,  and  sound,  and  odour,  and 
taste,  are  not  felt  in  the  organs  they  impress;  it  is  the  sensitive 
centre  that  sees,  and  hears,  and  smells,  and  tastes.  You  have 


OF  SENSATIONS. 


391 

only  to  interrupt  by  compression  of  the  nerves,  the  communi- 
cation between  the  organs  and  the  brain,  and  all  consciousness 
of  the  impressions  of  objects,  all  sensation  is  suspended. 

The  torturing  pains  of  a whitlow  cease,  if  you  bind  the  arm 
so  strongly  as  to  compress  the  nerve  which  carries  the  sensation 
to  the  brain.  A living  animal,  under  experiment,  suffers  nothing 
from  the  most  cruel  laceration,  if  you  have  first  cut  the  nerves 
of  the  parts  on  which  you  are  operating.  To  conclude,  the  or- 
gans of  sense,  and  the  nerves  which  communicate  between  them 
and  the  brain,  shall  have  suffered  no  injury,  shall  be  in  a perfect 
state  for  receiving  and  transmitting  the  sensitive  impression,  yet 
no  phenomena  of  sensation  can  take  place,  if  the  brain  be  dis- 
eased: when  it  is  compressed,  for  instance,  by  a collection  of 
fluid,  or  by  a splinter  from  the  skull  in  a wound  of  the  head. 
This  organ  is,  therefore,  the  immediate  instrument  of  sensa- 
tions, of  which  impressions  made  on  the  others  are  only  the 
occasional  causes.  This  modification  of  sensibility,  which  serves 
to  establish  the  relations  of  the  living  being  with  objects  with- 
out, would  be  correctly  denominated  cerebral  sensibility^  but 
even  in  animals  without  brain,  or  distinct  nervous  system,  that 
it  is  very  manifest.  The  sensibility,  in  virtue  of  which  the  poly- 
pus dilates  its  cavity,  for  the  admission  of  its  prey,  and  con- 
tracts itself  to  retain  it,  is,  in  fact,  quite  distinct  from  that 
sensibility  of  nutrition^  by  which  its  substance  is  enabled  to  take 
to  itself  nutritious  juices. 

The  brain,  as  Cabanis  has  well  expressed  it,  acts  upon  the  im- 
pression transmitted  by  the  nerves,  as  the  stomach  upon  the 
aliments  it  receives  by  the  oesophagus:  it  does,  in  its  own  way, 
digest  them;  set  in  motion  by  the  impulse  it  receives,  it  begins 
to  re-act,  and  that  re-action  is  the  perceptive  sensation.,  or  per- 
ception. From  that  moment,  the  impression  becomes  an  idea, 
it  enters  as  an  element  into  thought,  and  becomes  subject  to  the 
various  combinations  that  are  necessary  to  the  phenomena  of 
understanding.* 

CLIII.  Our  sensations  are  nothing  but  modifications  of  our 
being;  they  are  not  qualities  of  the  objects:  no  body  has  colour 

* I ought  to  observe  that  the  terms  thought  raid  understanding  are,  in  my 
opinion,  synonimous;  both  are  alike  an  abridged  expression  of  the  whole  of 
the  operation  of  the  sensitive  centre. 


392 


OF  SENSATIONS. 


to  the  blind  from  birth;  the  rose  has  lost  Its  most  precious 
quality  to  him  who  has  lost  his  smell;  he  knows  it  from  the 
anemone,  only  by  its  colour,  its  figure,  &c.  We  perceive 
nothing  but  within  ourselves.  It  is  only  by  habit,  only  by  apply- 
ing different  senses  to  the  examination  of  the  same  object, 
that  we  are  at  last  able  to  separate  it  from  our  own  existence; 
to  conceive  of  it  as  distinct  from  ourselves,  and  from  the  other 
bodies  with  which  we  are  acquainted;  in  a word,  to  refer  to  out- 
ward objects  the  sensations  that  take  place  within  ourselves. 
Our  ideas  come  to  us  only  by  the  senses;  there  are  none  innate, 
as  was  imagined  till  the  time  of  Locke,  who  has  allotted  to  the 
refutation  of  this  error  a large  part  of  his  valuable  work  on  the 
Human  Understanding.  The  child  that  opens  its  eyes  to  the 
light,  is  prepared  for  the  acquisition  of  ideas  by  this  merely,  that 
it  has  senses;  that  is,  that  it  is  susceptible  of  impressions  from 
the  objects  that  surround  it. 

It  is  inaccurate,  however,  to  compare,  as  some  philosophers 
have  done,  the  brain  of  a child  new-born  to  a blank  tablet,  on 
which  arc  to  be  figured  all  the  future  acts  of  his  intelligence.  If 
sensation  came  only  from  without,  if  the  external  senses  were 
the  only  organs  that  could  send  impressions  to  the  cerebral 
centre,  the  understanding,  at  the  moment  of  birth,  had  indeed 
been  nothing,  and  the  comparison  of  its  organs  to  a sheet  of 
white  paper,  or  to  a slab  of  Parian  marble,  on  which  not  a 
character  were  drawn,  had  been  perfectly  correct.  But  we  are 
compelled  to  acknowledge  with  Cabanis,  two  sources  of  ideas 
quite  distinct  from  each  other:  the  external  senses,  and  the  inter- 
nal organs.  These  Inward  sensations,  springing  from  functions 
that  are  carrying  on  within  us,  are  the  cause  of  those  instinctive 
determinations,  by  which  the  new-born  child  seizes  the  nipple  of 
its  mother,  and  sucks  the  milk  by  a very^  complicated  process; 
which  directs  the  young  of  animals  the  moment  after  birth,  and 
sometimes  in  the  very  act  of  birth,  while  their  limbs  are  y^et  en- 
gaged in  the  vagina,  to  seize  upon  the  dug  of  their  dam.  In- 
stinct, as  the  author  just  quoted  has  very  justly  observed,  springs 
from  impressions  received  by  the  interior  organs,  whilst  reason- 
ing is  the  produce  of  external  sensations;  and  the  etymology  of 
the  word  instinct,  composed  of  two  Greek  words,  signifying 


OF  SENSATIONS.  593 

“ to  prick,”  &c.  “ within,”  agrees  with  the  meaning  we  assign 
to  it. 

These  two  parts  of  the  understanding,  reason  and  instinct, 
unite  and  blend  together,  to  produce  the  intellectual  system,  and 
the  various  determinations  of  mental  action.  But  the  part  that 
each  bears  in  the  generation  of  ideas,  is  very  different  in  ani= 
mals,  whose  grosser  external  senses  allow  instinct  to  predomi- 
nate;  and  in  man,  in  whom  the  perfection  of  these  senses,  and 
the  art  of  signs,  which  perpetuate  the  transient  thought,  aug- 
ment the  power  of  reason,  while  they  enfeeble  instinct.  It  is  easy 
to  conceive,  that  the  brain,  assailed  by  a crowd  of  impressions 
from  without,  will  regard  less  attentively,  and  therefore  suffer 
to  escape,  the  greater  part  of  those  that  result  from  internal  ex- 
citation. Instinct  is  more  vigorous  in  savage  man,  and  its  rela- 
tive perfection  is  his  compensation  for  the  advantages  which 
superior  reason  brings  to  man  in  civilization.  The  moral  and 
intellectual  system  of  the  individual,  considered  at  different 
periods  of  life,  owes  more  to  internal  sensation  the  less  it  is 
advanced;  for,  instinct  declines  as  reason  is  strengthened  and 
enlarged. 

Thus,  though  all  the  phenomena  of  understanding  have  their 
source  in  phvsical  sensibility,  this  sensibility  being  set  in  action 
by  two  sorts  of  impressions,  the  brain  of  an  infant  just  born,  has 
already  the  consciousness  of  those  which  spring  from  the  inter- 
nal motion;  and  it  is  from  these  impressions  that  it  executes 
certain  spontaneous  movements,  of  which  Locke  and  his  fol- 
lowers could  find  no  explanation;  accordingly,  the  partisans  of 
innate  ideas  looked  upon  them  as  the  strongest  confirmation  of 
their  system;  but  these  ideas,  anterior  to  all  action  of  outward 
objects  on  the  senses,  arc  simple,  few,  and  extending  to  a very 
small  number  of  wants;  the  child  is  but  a few  hours  old,  and 
already  it  expresses  a multitude  of  sensations,  that  throng  upon 
it  from  the  instant  of  its  birth;  sensations,  which  have  passed  to 
the  brain,  combined  themselves  there,  and  entered  into  the  ac- 
tion of  the  will  with  a velocity  that  equals,  if  it  does  not  surpass, 
that  of  light. 

It  is  only,  after  laying  down  between  the  sources  of  our  know- 
ledge a very  exact  line  of  demarcation;  after  scrupulously  dis- 
tinguishing the  rational  from  the  instinctive  determinations; 

3 D 


394 


OF  SENSATIONS. 


acknowledging  that  age,  sex,  temperament,  health,  disease,  cli- 
mate, and  habit,  which  modify  our  physical  organization,  must, 
by  a secondary  effect,  modify  these  lastj  that  we  can  possibly 
understand  the  diversity  of  humours,  of  opinions,  of  characters, 
and  of  genius.  He  who  has  well  appreciated  the  effect,  on  the 
judgment  and  reason,  of  the  sensations  that  spring  from  the  ha- 
bitual state  of  the  internal  organs,  sees  easily  the  origin  of  those 
everlasting  disputes  on  the  distinction  between  the  sensitive  and 
the  rational  soul;  why  some  philosophers  have  believed  man 
solicited  for  ever  by  a good  or  evil  genius,  spirits  which  they 
have  personified  under  the  names  of  Oromazes  and  Arimanes, 
betwixt  whom  they  imagined  eternal  war;  the  contest  of  the 
soul  with  the  senses,  of  the  spirit  with  the  flesh,  of  the  concu- 
piscent and  irascible  with  the  intellectual  principle,  that  contra- 
diction which  St.  Paul  laboured  under,  when  he  said  in  his 
Epistle  to  the  Romans,  that  his  members  were  in  open  war  with 
his  reason.  These  phenomena,  which  suggest  the  conception  of 
a two-fold  being  {^Homo  duplex,  Buffon),  are  nothing  but  a ne- 
cessary strife  betwixt  the  determinations  of  instinct  and  the  de- 
terminations of  reason;  between  the  often  times  imperious  wants 
of  the  organic  nature,  and  the  judgment  which  keeps  them  un- 
der, or  deliberates  on  the  means  of  satisfying  them,  without 
offending  received  ideas  of  fitness,  of  duty,  of  religion,  &c. 

CL IV.  A being,  absolutely  destitute  of  sensitive  organs, 
would  possess  only  the  existence  of  vegetation:  if  one  sense 
were  added,  he  would  not  yet  possess  understanding,  because, 
as  Condillac  has  shown,  the  impressions  produced  on  this  only 
sense,  would  not  admit  of  comparison;  it  would  all  end  in  an 
inward  feeling,  a perception  of  existence,  and  he  would  believe 
the  things  w'hich  affected  him  to  be  a part  of  his  being.  The 
fundamental  truth,  so  completely  made  out  by  modern  meta- 
physicians, is  found  distinctly  stated  in  the  writings  of  Aris- 
totle:* and  there  is  room  for  surprise  that  that  father  of  philo- 
sophy should  have  merely  recognized  it,  without  conforming 
to  its  doctrine:  but  still  more  that  it  should  have  been  for  so 
many  ages  disregarded  by  his  successors.  So  absolutely  is  sen- 
sation the  source  of  all  our  knowledge,  that  even  the  measure 


j7  e«r  in  intellectu,  quod  non  priits  fuerit  in  sensu 


OF  SENSATIONS. 


395 


of  understanding  Is  according  to  the  number  and  perfection  of 
the  organs  of  sense;  and  that  by  successively  depriving  them  of 
the  intelligent  being,  we  should  lower,  at  each  step,  his  intel- 
lectual nature;  whilst  the  addition  of  a new  sense  to  those  we 
now  possess,  might  lead  us  to  a multitude  of  unknown  sensa- 
tions and  ideas,  would  disclose  to  us  in  the  beings  we  are  con- 
cerned with,  a vast  variety  of  new  relations,  and  would  greatly 
enlarge  the  sphere  of  our  intelligence. 

The  impression,  produced  on  any  organ,  by  the  action  of  an 
outward  body,  does  not  constitute  sensation;  it  is  further  requi- 
site, that  the  impression  be  transmitted  to  the  brain,  that  it  be 
there  perceived^  that  is,  felt  by  that  organ;  the  sensation  then 
becomes  perception^  and  this  first  modification  supposes,  as  is 
apparent,  a central  organ,  to  which  the  impressions  on  the  or- 
gans may  be  carried.  The  cerebral  fibres  are  more  or  less  dis- 
turbed by  the  sensations  sent  to  them,  at  once,  from  all  the  or- 
gans of  sense;  and  we  should  acquire  but  confused  notions  of  the 
bodies  from  which  they  proceed,  if  one  stronger  perception  did 
not  silence,  as  it  were,  the  rest,  and  fix  the  attention.  In  this 
concentration  of  the  soul  upon  a single  object,  the  brain  is 
feebly  stirred  by  many  sensations  that  leave  no  trace;  it  is  thus 
that  after  the  attentive  perusal  of  a book,  we  have  lost  the  sen- 
sations that  were  produced  by  the  different  colour  of  the  paper 
and  the  letters. 

When  a sensation  is  of  short  duration,  our  knowledge  of  it  is 
so  light,  that  soon  there  remains  no  remembrance  of  it.  It  is 
thus,  that  we  do  not  perceive,  every  time  we  wink,  that  we 
pass  from  light  to  darkness,  and  from  darkness  to  light.  If  we  fix 
our  attention  on  this  sensation,  it  affects  us  more  permanently. 
After  occupying  oneself,  for  a given  time,  with  a number  of 
things,  with  but  moderate  attention  to  each;  after  reading,  for 
instance,  a novel,  full  of  events,  each  of  which  in  its  turn  has 
interested  us,  we  finish  it  without  being  tired  of  it,  and  arc 
surprized  at  the  time  it  has  taken  up.  It  is  because  successive 
and  light  impressions  have  effaced  one  another,  till  we  have  for- 
gotten all  but  some  of  the  principal  actions.  Time  ought  then 
to  appear  to  us  to  have  passed  rapidlv;  for,  as  Locke  has  well 
said,  in  his  Essay  on  the  Human  Understanding,  “ We  con- 
ceive the  succession  of  times  only  by  that  of  our  thoughts,” 


or  SENSATIONS. 


396 

This  faculty  of  occunying  oneself  long  and  exclusively  with 
the  same  idea,  of  concentrating  all  the  intellectual  faculties  on 
one  object,  of  bestowing  on  the  contemplation  of  it  alone,  a 
lively  and  well  supported  attention^  is  found  in  greater  or  less 
strength  in  different  minds:  and  some  philosophers  appear  to 
me  to  have  explained,  very  plausibly,  the  different  capacity  of 
different  minds,  the  various  degrees  of  instruction  of  which  we 
are  capable,  by  the  degree  of  attention  we  are  able  to  give  to 
the  objects  of  our  studies. 

Who,  more  than  the  man  of  genius,  pauses  on  the  examina- 
tion of  a single  idea;  considers  it  with  more  profound  reflexion, 
under  more  aspects  and  relations;  bestows  on  it,  in  short,  more 
entire  attention? 

Attention  is  to  be  considered  as  an  act  of  the  will,  which 
keeps  the  organ  to  one  sensation,  or  prepares  it  for  that  sensa- 
tion, so  as  to  receive  it  more  deeply.  To  look,  is  to  see  with  at- 
tention; to  listen,  is  to  hear  attentively:  the  smell,  the  taste,  in 
the  same  way,  are  fixed  upon  an  odour,  or  a flavour,  so  as  to  re- 
ceive from  them  the  fullest  impression.  In  all  these  cases,  the 
sensation  may  be  involuntary;  but  the  attention  by  which  it  is 
heightened,  is  an  act  of  the  will.  This  distinction  has  already 
been  well  laid  down  with  regard  to  the  feeling,  which  is  only 
the  touch  exerted  under  the  direction  of  the  will. 

According  to  the  strength  or  faintness  of  the  impression  that 
a sensation,  or  an  idea  (which  is  but  a sensation  operated  upon 
by  the  cerebral  organ),  has  produced  on  the  fibres  of  that  organ, 
will  be  the  liveliness  and  permanence  of  the  reccollection.  Thus, 
we  may  have  reminiscence  of  it,  or  recal  faintly  that  we  have 
been  so  affected;  or  memory^  which  is  a representative  of  the 
object,  with  some  of  its  characteristic  attributes,  as  colour, 
bulk,  he. 

The  pains  that  appear  to  be  felt  in  limbs  which  we  have  lost, 
have  not  their  place  in  the  part  that  is  left;  the  brain  is  not  de- 
ceived when  it  refers  to  the  foot,  the  cause  of  the  sufferings  of 
which  is  in  the  stump,  after  the  amputation  of  the  leg  or  thigh. 
I have  at  this  moment  before  me,  the  case  of  a woman  and  of 
a young  man,  whose  leg  and  thigh  I took  off  for  scrophulous 
caries,  of  many  years  standing,  and  incurable  by  an}'^  other 
means.  The  wound,  from  the  operation,  is  completely  cica- 


OF  SENSATIONS. 


397 

trised.  The  stump  has  not  more  sensibility  than  any  other  part 
covered  by  integuments,  since  it  may  be  handled  without  pain. 
And  yet,  both,  at  intervals,  and  especially  when  the  atmosphere 
is  highly  electrified,  complain  of  pains  in  the  limbs  which  they 
have  lost  some  months  ago.  They  recognize  them  by  certain 
characters,  for  those  of  their  disease.  They,  like  all  percep= 
tions,  are  manifestly  given  in  charge  to  the  memory,  which 
reproduces  them,  when  the  cerebral  organ  repeats  the  action, 
once  occasioned  by  the  impressions  of  the  disease. 

Finally,  if  the  brain  is  easy  of  excitation,  and  at  the  same 
time,  faithful  in  preserving  the  impressions  it  has  received,  it 
will  possess  the  power  of  bringing  up  ideas  with  all  their  con- 
nected and  collateral  ideas;  of  reproducing  them,  in  some  sort, 
by  recalling  the  entire  object,  whilst  memory  presents  us  with 
a few  of  its  qualities  only.  This  creative  faculty  is  called  ima- 
gination. If  it  sometimes  produces  monsters,  it  is  that  the  brain, 
by  its  powers  of  associating,  connecting,  combining  ideas,  repro- 
duces them  in  an  order  not  according  to  nature,  gathers  them 
under  capricious  associations,  and  gives  occasion  to  many  erro- 
neous judgments. 

When  the  mind  brings  together  two  ideas,  when  it  compares 

them,  and  determines  on  their  analogy,  it  judges.  A certain 
number  of  judgments^  in  series,  form  a reasoning.  To  reason, 

then,  is  only  to  judge  of  the  relations  that  exist  among  the  ideas 
with  which  the  senses  supply  us,  or  which  are  reproduced  by 
imagination. 

It  is  with  the  faculties  of  the  soul,  as  with  those  of  the  body. 
When  called  into  full  exertion,  the  intellectual  organ  gains  vi- 
gour; it  languishes  in  too  long  repose.  If  we  exercise  certain  fa- 
culties only,  they  are  greatly  developed  to  the  prejudice  of  the 
rest.  It  is  thus  that,  by  the  study  of  mathematics,  soundness  of 
judgment  is  acquired,  and  precision  of  reasoning,  to  the  extinc- 
tion of  imagination,  which  never  rises  to  great  strength  without 
injury  to  the  judging  and  reasoning  powers.  The  descriptive 
sciences  employ  especially  the  memory,  and  it  is  seldom  that 
they  much  enlarge  the  minds  of  those  who  study  them  exclu- 
sively. 

CLV.  Condillac  has  immortalized  his  name,  by  discovering, 
the  first,  and  by  demonstrating  irrefragably,  that  signs  are  as 


398 


OP  SENSATIONS. 


necessary  to  the  formation  as  to  the  expression  of  ideas;  that 
language  is  not  less  useful  for  thinking  than  for  speaking;  that 
if  we  could  not  attach  the  notions  once  acquired  to  received 
signs,  they  would  remain  always  unconnected,  and  uncom- 
pleted, since  we  should  have  no  power  to  associate  and  com- 
pare them,  and  to  determine  their  relations.  It  is  the  imperfec- 
tion or  the  total  want  of  signs,  for  fixing  their  ideas,  that  makes 
the  infancy  of  the  lower  animals  perpetual.  It  is  this  that  makes 
it  impossible  for  them  to  transmit  to  another  generation,  or  even 
to  communicate  one  with  another,  the  acquisitions  of  individual 
experience:  which  experience  is  indeed,  bv  the  same  cause,  re- 
strained within  very  narrow  limits,  and  confined  to  a few  sim- 
ple notions,  a few  ideas  resting  merely  on  its  wants  and  on  its 
powers.  If  there  were  not  signs  to  preserve  ideas,  and  to  con- 
nect them,  memory  would  be  nothing,  all  impressions  would  be 
effaced  soon  after  they  were  felt,  all  collections  of  ideas  would 
be  dissolved  as  soon  as  formed,  (if  they  could  be  formed  at  all) 
our  ignorance  would  be  indefinitely  prolonged,  and  we  should 
reach  old  age,  with  a mind  still  in  its  infancy. 

When  we  reflect  on  a subject,  it  is  not  directly  on  the  ideas, 
but  on  the  words  expressing  them,  that  the  mind  operates;  we 
should  never  have  the  idea  of  numbers,  if  we  had  not  assigned 
distinct  names  to  numbers,  whether  single  or  collected.  Locke 
speaks  of  some  Americans,  who  had  no  idea  of  the  number 
thousand,  because  the  words  of  their  language  expressed  no- 
thing beyond  the  number  twenty.  La  Condamlne  informs  us, 
in  his  narrative,  that  there  are  some  who  count  only  to  three, 
and  the  word  they  employ  to  express  the  number  is  so  compli- 
cated, of  a pronunciation  so  long  and  difficult,  that,  as  Condillac 
observed,  it  is  not  surprising,  that  having  begun  with  a method 
so  inconvenient,  they  have  not  been  able  to  advance  any  further. 
“ Deny,  (says  this  writer),  to  a superior  mind,  the  use  of  letters, 
“how  much  of  knowledge  you  put  out  of  his  reach,  which  an 
“ ordinary  capacity  will  attain  to  without  difficulty.  Go  on,  and 
“take  from  him  the  use  of  speech,  the  lot  of  the  dumb  will 
“ show  you,  how  narrow  are  the  limits  within  which  you  con- 
“fine  him.  Finally,  take  from  him  the  use  of  all  sorts  of  signs, 
•^Met  him  be  unable  to  find  the  least  sign  for  the  most  ordinary 
“ thought,  and  you  have  an  idiot.”* 

* Essai  sur  Torigine  des  Gonnoissanc*s  humaines,  sec.  4. 


OF  SENSATIONS. 


599 


We  are  made  acquainted  by  travellers  with  certain  tribes,  so 
backward  in  the  art  of  expressing  their  ideas  by  signs,  that  they 
seem  to  serve  as  a link  between  civilized  nations  and  certain 
species  of  animals,  whose  instinct  has  been  perfected  by  educa- 
tion. One  might  even  assert,  that  there  is  less  distance,  in  re- 
spect to  intelligence,  from  man  in  that  extreme  abasement  to 
the  higher  animals,  that  there  is  to  a man  of  superior  genius, 
such  as  Bacon,  Newton  or  Voltaire. 

In  another  part  of  the  same  work,  after  having  demonstrated 
that  languages  are  real  analytic  methods,  that  the  sciences  may 
be  reduced  to  well  constructed  languages,  he  shows  how  power- 
ful is  their  influence  in  the  cultivation  of  the  mind.  But  he  shall 
speak  himself,  with  that  clearness  of  expression,  which  is  the 
characteristic  and  the  charm  of  his  writings.  “ Languages  are 
like  the  cyphers  of  the  geometricians;  they  present  new  viewsto 
the  mind,  and  expand  it  as  they  are  brought  nearer  to  perfec- 
tion. The  discoveries  of  Newton  had  been  prepared  for  him,  by 
the  signs  that  had  been  already  contrived,  and  the  methods  of 
calculation  that  had  been  invented.  If  he  had  arisen  sooner,  he 
might  have  been  a great  man  to  his  own  age,  but  he  would  not 
have  been  the  admiration  of  ours.  It  is  the  same  in  other  de- 
partments.” 

The  most  scanty  languages  have  been  formed  in  the  most 
barren  countries.  The  savage  who  strays  along  the  desert  shores 
of  New  Zealand,  needs  but  few  signs  to  distinguish  the  small 
number  of  objects  that  habitually  impress  his  senses;  the  sky, 
the  earth,  the  sea,  fire,  shells,  the  fish,  that  form  his  chief  food, 
the  quadrupeds,  and  the  vegetables,  which  are  but  few  in  num- 
ber under  this  severe  climate,  are  all  that  he  has  to  name  and  to 
know;  accordingly,  his  vocabulary  is  very  small;  it  has  been 
given  to  us  by  travellers  in  the  compass  of  a few  pages.  A co- 
pious language,  one  capable  of  expressing  a great  variety  of  ob- 
jects, of  sensations  and  of  ideas,  supposes  high  civilization  in  the 
people  among  whom  it  is  spoken.  You  hear  complaints  of  the 
perpetual  recurrence  of  the  same  expressions,  the  same  thoughts, 
the  same  images,  in  the  poetry  of  Ossian;  but  living  amidst  the 
barren  rocks  of  Scotland,  the  bards  could  not  speak  of  things 
of  which  nothing,  on  the  soil  they  inhabited,  could  supply  them 
with  the  idea.  The  monotony  of  their  languages  was  involved 


OF  SENSATIONS. 


400 

in  that  of  the  impressions,  always  produced  by  rocks,  mists, 
winds,  the  billows  of  the  ireful  ocean,  the  gloomy  heath,  and 
the  silent  pine,  &c.  The  repetition  of  the  same  expressions, 
in  the  Scriptures,  shows  chat  civilization  had  not  made  the  same 
progress  among  the  Hebrews,  as  among  the  Greeks  and  Ro- 
mans. The  connexion  there  is  between  the  genius  of  a language, 
and  the  character  of  the  people  that  speak  it;  the  influence  of 
climate,  of  government,  and  of  manners  on  language;  the  reason 
why  the  great  writers,  in  every  department,  appear  together,  at 
the  very  time  in  which  a language  reaches  its  perfection  and  ma- 
turity, &c.;  these  are  problems  that  suggest  themselves,  and 
would  well  merit  our  endeavours  to  obtain  solution,  did  not  the 
investigation  manifestly  lead  beyond  the  limits  of  our  enquiry. 

Though  Condillac  has  said,  repeatedly,  in  his  works,  that  all 
the  operations  of  the  soul  are  merely  sensation,  variously  trans- 
formed; that  all  its  faculties  are  included  in  the  single  one  of 
sense;  his  analysis  of  thought  leaves  still  much  doubt  and  un- 
certainty on  the  real  character  and  relative  importance  of  each 
of  her  faculties. 

The  merit  of  dispersing  the  mist  which  covered  this  part  of 
metaphysics,  remained  for  M.  Tracy.  His  Elements  of  Ideolo- 
gy,* leave  nothing  to  be  wished  for  on  this  subject.  I shall 
extract  some  of  its  main  results,  referring  the  reader  for  the  rest 
to  the  work. 

To  think  is  only  to  feel;  and  to  feel  is,  for  us,  the  same  as  to 
exist:  for,  it  is  by  sensation  we  know  of  our  existence.  Ideas, 
or  perceptions,  are  either  sensations,  properly  so  called,  or  re- 
collections, or  relations  which  we  perceive,  or,  lastly,  the  desire 
that  is  occasioned  in  us  by  these  relations.  The  faculty  of 
thought,  therefore,  falls  into  the  natural  subdivision  of  sensi- 
bility, properly  termed  memory,  judgment,  and  will.  To  feel, 
properly  speaking,  is  to  be  conscious  of  an  impression;  to  re- 
member, is  to  be  sensible  of  the  remembrance  of  a past  impres- 
sion; to  judge,  is  to  feel  relations  among  our  perceptions;  lastly, 
to  will,  is  to  desire  something.  Of  these  four  elements,  sensa- 
tions^ recollections,  judgments,  and  desires,  are  formed  all  com- 

* Eletnens  d’Ideolog'ie,  par  M.  Destutt  Tracy,  senateur,  Membre  d« 
ITnstitut. 


OF  SENSATIONS. 


401 


pound  ideas.  Attention  is  but  an  act  of  the  will;  comparison  can- 
ntftbe  separated  from  judgment,  since  we  cannot  compare  two 
objects  without  judging  them;  reasoning  is  only  a repetition  of 
the  act  of  judging;  to  reflect,  to  imagine,  is  to  compose  ideas, 
analyzableinto  sensations,  recollections,  judgments,  and  desires. 
This  sort  of  imagination,  which  is  only  certain  and  faithful  me- 
mory, ought  not  to  be  distinguished  from  it. 

Finally, want,  uneasiness,  inquietude, desire,  passions,  &c.  are 
either  sensations  or  desires.  There  is  room,  therefore,  to  re- 
proach Condillac  with  having  divided  the  human  mind  into 
understanding  and  will  only:  because  the  first  term  includes 
actions  too  unlike,  such  as  sensation,  memory,  judgment;  and 
with  having  run  into  the  opposite  extreme,  in  the  too  great  mul- 
tiplication of  secondary  divisions. 

CLVI.  Disorders  of  thought.  Philosophers  would  undoubt- 
edly attain  to  a much  profounder  knowledge  of  the  intellectual 
faculties  of  man,  if  they  joined  to  the  study  of  their  regular  and 
tranquil  action,  that  of  the  many  disordered  actions  to  wJiich 
they  are  liable.  It  is  not  enough,  if  we  would  understand  them 
aright,  to  watch  their  operation  when  the  soul  is  undisturbed 
and  at  ease:  we  must  follow  it  in  its  perturbations  and  wander- 
ings; we  must  see  its  powers,  now  separating  themselves  from 
those  with  which  they  ought  to  act,  now  combining  with  them 
under  false  perceptions;  sometimes  altogether  drooping,  and 
sometimes  starting  into  an  extreme  violence  of  action,  of  which 
we  can  neither  mistake  the  importance  nor  the  nature;  and,  as 
the  greater  part  of  our  ideas  are  derived  from  the  analogies  we 
are  able  to  discern  among  the  objects  that  supply  them,  amidst 
these  troubles  of  human  passion  and  human  reason,  we  learn  to 
conceive  more  profoundly  of  their  nature,  than  if  we  had  been 
satisfied  with  observing  them  in  the  calm  of  their  natural  con- 
dition. 

The  observation  of  mania  is  yet  too  imperfect  in  the  number, 
variety,  and  precision  of  its  facts,  to  fix  the  classification  of  the 
species  of  mental  alienation,  according  to  the  intellectual  faculty 
that  is  disordered  in  each.  Professor  Pinel  has,  nevertheless, 
ventured  to  ground  his  distinctions  of  the  species  of  mania,  on 
the  labours  of  modern  psychologists,  and  shown  that  all  might 
be  referred  to  five  kinds,  which  he  marks  by  the  names  of 

3 E 


402 


OF  SENSATIONS. 


melancholy,  of  mania  without  delirium,  mania  with  delirium, 
dementia,  and  idiotcy.*  In  the  first  four  kinds,  there  is  perver- 
sion of  the  mental  faculties,  which  are  in  languid  or  excessive 
action.  We  are  not  to  look  for  the  cause  of  these  derangements 
in  vice  of  original  conformation;  for,  melancholy,  mania  with  or 
Vithout  delirium,  and  madness,  scarcely  ever  appear  before  pu- 
berty. It  is  agreed,  among  observers,  that  almost  all  maniacs 
have  become  so  between  twenty  and  forty  years  old;  that  very 
few  have  lost  their  reason  either  before  or  after  this  stormy  pe- 
riod of  life,  wherein  men,  yielding,  by  turns,  to  the  torments  of 
love  and  of  ambition,  of  fear  and  of  hope,  to  the  sweet  illusions 
of  happiness,  and  the  realities  of  suffering,  consumed  with  pas- 
sions for  ever  reviving,  often  repressed,  and  rarely  satisfied,  feel 
their  intellectual  powers  impaired,  annihilated,  or  abased  by 
that  tempest  of  the  moral  nature,  which  has  well  been  compared 
to  the  storms  which,  in  their  violence,  lay  desolate  the  flourish- 
ing earth. 

We  are  compelled  to  grant,  that  our  acquaintance  with  the 
structure  of  the  brain  and  of  the  nerves  is  too  imperfect,  that 
dissections  of  the  bodies  of  maniacs  have  been  too  few,  and 
those  often  by  physicianst  too  little  familiar  with  the  minute 
structure  of  the  sensitive  organ,  to  warrant  us  in  asserting  or 
denying,  that  derangement  of  intellect  depends  constantly  on 
organic  injury;  though  it  is  highly  probable,  many  facts  at  least, 
collected  by  observers,  who,  like  Morgagni,  deserve  the  utmost 
confidence,  authorize  the  belief,  that  the  consistence  of  the  brain 
is  increased  in  some  maniacs,  who  are  distinguished  by  the 
most  obstinate  and  unvarying  adherence  to  their  ruling  ideas; 
that  it  is,  on  the  other  hand,  soft,  watery,  and  in  a kind  of  inci- 
pient dissolution  in  some  others,  whose  incoherent  ideas,  after 
their  aptitude  for  association,  and  for  transformation  into  judg- 
ments is  gone,  succeed  one  another  rapidly,  and  seem  to  pass 
away  without  a trace,  &c. 

If,  in  the  multitude  of  maniacs,  the  organ  of  the  understand- 
ing suffer  only  imperceptible  injury,  it  is  very  remarkably 

* For  more  ample  esplanation  I must  refer  to  the  work.  Traite  medico-phi- 
hsophiqiie  sur  I’-llienation  mentale  mi  la  Manie,  par  P.  Pinel.  Paris,  1800. 

■)•  This  censure  is  especially  applicable  to  the  researches  of  Dr.  Greding’. 


OF  SENSATIONS. 


403 


changed  In  Idiots.  The  almost  entire  obliteration  of  the  intel- 
lectual faculties,  which  constitutes  idiotcy,  when  it  is  not 
brought  on  by  some  strong  and  sudden  shock,  some  unex- 
pected and  overwhelming  emotion,  breaking  down  at  once 
all  the  springs  of  thought,  when  It  is  an  original  defect,  is 
always  connected  with  mal-conformatlon  of  the  skull,  with 
the  constraint  of  the  organs  it  encloses.  These  defects  of  or- 
ganization lie,  as  M.  Pinel  observes,  in  the  excessive  small- 
ness of  the  head,  to  the  whole  stature,  or  to  the  want  of  pro- 
portion among  the  different  parts  of  the  skuil.  Thus  in  the 
idiot,  whose  head  is  given  in  the  work  on  mania,  (pi.  2,  fig.  6.) 
it  is  only  the  tenth  of  the  whole  height,  whilst  it  should  be 
something  more  than  a seventh,  if  we  take  the  Apollo  of  Bel- 
vedere as  the  type  of  the  ideal  perfection  of  the  human  figure. 
An  idiot,  whom  I occasionally  see,  has  the  occipital  extremity 
of  the  head  so  much  contracted,  that  the  large  extremity  of 
the  oval  formed  by  the  upper  face,  instead  of  being  placed 
at  the  back,  as  in  other  men,  is,  on  the  contrary,  turned  for- 
wards and  answers  to  the  forehead,  which  Itself  slopes  towards 
the  sinciput.  The  vertical  diameter  of  the  skull  is  inconside- 
rable. The  head,  thus  shortened  from  above  downwards,  is 
much  flattened  on  the  sides.  The  hands  and  feet  are  very 
small,  and  often  cold;  the  genitals,  on  the  contrary,  are  ex- 
tremely large. 

In  two  other  children,  equally  idiots,  and  now  in  the  hospital 
of  St.  Louis,  the  skull,  very  large  behind,  ends  in  a very  con- 
tracted extremity,  and  the  forehead  is  very  short,  and  not  more 
than  two  inches  and  a half  wide,  measuring  from  the  semi-cir- 
cular process  which  terminates,  at  the  upper  part,  the  temporal 
fossa,  to  the  commencement  of  the  same  process  on  the  other 
side.  The  excessive  growth  of  the  genitals  is  not  less  conspi- 
cuous; they  are,  in  these  two  children,  one  ten,  the  other  twelve 
years  old,  as  well  as  in  the  first  of  whom  I spoke,  who  is  four- 
teen, of  larger  size  than  is  commonly  seen  after  the  appearance 
of  puberty.  There  is  nothing  to  indicate  that  this  season  is  at- 
tained by  these  three  idiots. 

The  same  excess  of  growth  is  found  more  conspicuously 
among  the  cretins  of  the  Valais,  idiots  who  (in  consequence 


404 


OF  SENSATIONS. 


of  a weak  and  degraded  organization)  are  prone  to  lascivious- 
ness and  the  most  frequent  onanism. 

This  sort  of  opposition  in  the  relative  energy  of  the  intellec- 
tual organ,  and  of  the  system  of  reproduction,  in  the  develop- 
ment of  the  brain,  and  that  of  the  parts  of  generation,  is  a phe- 
nomenon which  must  strongly  interest  the  curiosity  and  engage 
the  attention  of  physiologists.  Who  is  there  unacquainted  with 
that  enervation  of  the  understanding,  that  intellectual  and  phy- 
sical debility,  which  indulgence  in  the  pleasures  of  love  brings 
on,  if  we  exceed  ever  so  little  the  bounds  of  scrupulous  mode- 
ration? Castration  modifies  the  moral  character  of  men  and  ani- 
mals. at  least,  as  powerfully  as  their  physical  organization,  as 
M.  Cabanis  has  shown,  in  treating  of  the  influence  of  the  sexes 
on  the  origin  and  growth  of  the  moral  and  intellectual  powers. 

CLVII.  Our  physical,  therefore,  holds  our  moral  nature  un- 
der a strict  and  necessary  dependence;  our  vices  and  our  vir- 
tues, sometimes  produced  and  often  modified  by  social  educa- 
tion, are  frequently,  too,  results  of  organization.  To  the  conclu- 
sive proofs  which  the  philosopher  I have  just  named,  who  is  an 
honour  to  his  profession,  brings  forward  of  the  influence  of  the 
physical  on  the  moral  human  being,  I will  only  add  a single  ob- 
servation. It  is  not,  certainly,  the  first  that  has  been  made  of 
the  kind;  but  none  such,  I believe,  has  yet  been  published.  The 
reader  recollects,  I have  no  doubt,  the  old  woman  of  whom 
I have  spoken  in  treating  of  the  motions  of  the  brain,  which  an 
enormous  caries  of  the  bones  of  the  skull  gave  an  opportunity 
of  observing  in  her.  I wiped  off  the  sanious  matter  which  co- 
vered the  dura  mater,  and  I,  at  the  same  time,  q^iestioned  the 
patient  on  her  situation;  as  she  felt  no  pain  from  the  compres- 
sion of  the  cerebral  mass,  I pressed  down  lightly  the  pledget  of 
lint,  and  on  a sudden  the  patient,  who  was  answering  my  ques- 
tions rationally,  stopped  in  the  midst  of  a sentence:  but  she  went 
on  breathing  and  her  pulse  continued  to  beat:  I withdrew  the 
pledget;  she  said  nothing:  I asked  her  if  she  remembered  my 
last  question:  she  said  not.  Seeing  that  the  experiment  was 
without  pain  or  danger,  I repeated  it  three  times,  and  thrice 
I suspended  all  feeling  and  all  intellect. 

A man  trepanned  for  a fracture  of  the  skull,  with  effusion  of 
blood  and  pus  on  the  dura  mater,  perceived  his  intellectual  fa- 


OF  SENSATIONS. 


40S 

culties  going,  the  consciousness  of  existence  growing  benumbed 
and  threatening  to  cease,  in  the  interval  of  each  dressing,  in  pro- 
portion as  the  fluid  collected. 

There  arc  surgical  observations  on  wounds  of  the  head  con- 
taining several  facts  that  may  be  connected  with  the  preceding 
observations.  There  is  no  one  who  has  had  syncope  of  more  or 
less  continuance,  but  knows  that  the  state  is  without  pain  or  un- 
easiness, and  leaves  no  consciousness  of  what  passed  whilst  it 
lasted.  It  is  the  same  after  an  apoplexy,  a fit  of  epilepsy,  See. 

The  history  of  temperaments  supplies  us  with  too  many  ex- 
amples of  the  strict  connexion  which  there  is  between  the  phy- 
sical organization  and  the  intellectual  and  moral  faculties,  to 
leave  any  necessity  for  dwelling  longer  on  this  truth,  which  no 
one  questions,  but  which  no  philosopher  has  yet  followed  into 
all  its  consequences. 

CLVIII.  An  English  writer,  in  a work  on  the  history  of 
mental  alienation,*  has  traced,  better  than  had  before  been 
done,  the  physiological  history  of  the  passions,  which  he  looks 
upon  as  mere  results  of  organization,  ranking  them  among  the 
phenomena  of  the  animal  economy,  and  with  abstraction  of  any 
moral  motian  that  might  attach  to  them.  — 

All  passion  is  directed  to  the  preservation  of  the  individual 
or  the  reproduction  of  the  species.  They  may  be  distinguished, 
therefore,  like  the  functions,  into  two  classes.  In  the  second,  we 
should  find  parental  love,  and  all  the  affections  that  protect  our 
kind  through  the  helplessness  of  its  long  infancy. 

But  Crichton,  with  the  greater  part  of  metaphysicians  and 
physiologists,  appears  to  me  not  to  have  settled  correctly  the 
meaning  that  should  belong  to  the  word  passion.  When  he 
gives  this  name  to  hunger,  an  inward  painful  sensation,  the 
source  of  many  determinations  of  many  kinds,  a powerful 
mover  of  savage  and  civilized  man,-— to  the  anxiety  which 
attends  the  breathing  an  air  deficient  in  oxygen, — to  the  im- 
pressions of  excessive  heat  and  cold, — to  the  troublesome  sen- 
sation produced  by  the  accumulation  of  urine  and  fecal  mat- 
ter,— to  the  feeling  of  weariness  and  fatigue  that  is  left  by 

* An  Inquiry  into  the  Nature  and  Origin  of  Metal  Derangement— London, 
1798. 2 vols.  8vo. 


406 


OF  SENSATIONS. 


violent  exertions, — he  confounds  sensation  with  the  passions 
or  desires  which  may  spring  from  it. 

It  is  to  avoid  extreme  wants,  of  which  a vigilant  foresight 
perceives  afar  olF  the  possibility, — it  is  to  satisfy  all  the  facti- 
tious wants  which  society  and  civilization  have  created,  that 
men  condemn  themselves  to  those  agitations,  of  which  honour, 
reputation,  wealth,  and  power,  are  the  uncertain  aim.  Our  pas- 
sions have  not  yet  been  analyzed  with  the  same  care  as  our 
ideas:  no  one  has  yet  duly  stated  the  differences  there  are,  in 
respect  to  their  number  and  energy,  betwixt  savage  man,  and 
man  in  the  midst  of  civilized  and  enlightened  society. 

As  the  habitual  state  of  the  stomach,  of  the  lungs,  of  the  liver 
and  internal  organs,  is  connected  with  certain  sets  of  ideas; — as 
every  vivid  sensation  of  joy  or  distress,  of  pleasure  or  pain, 
brings  on  a feeling  of  anxiety  in  the  praecordia, — the  ancients 
placed  in  the  viscera  the  seat  of  the  passions  of  the  soul:  they 
placed  courage  in  the  heart,  anger  in  the  liver,  joy  in  the  spleen, 
&c.  Bacon  and  Van  Helmont  seated  them  in  the  stomach;  Le- 
cat  in  the  nervous  plexuses;  other  physiologists  in  the  ganglions 
of  the  great  sympathetics.  See.  But  have  they  not  confounded 
the  effect  with  the  cause?  the  appetite  with  the  passion  to  which 
it  disposes?  The  appetites,  out  of  which  the  passions  spring,  re- 
side in  the  organs,  they  suppose  only  instinctive  determinations, 
whilst  passion  carries  with  it  the  idea  of  intellectual  exertion. 
Thus,  the  accumulation  of  semen  in  the  vesiculae,  which  serve 
for  its  reservoirs,  excites  the  venereal  appetite,  quite  distinct 
from  the  passion  of  love,  though  often  its  determining  cause. 
Animals  have  scarcely  more  than  appetite,  which  differs  as 
much  from  passion  as  instinct  from  intelligence.  However, 
the  brain  is  not  to  be  considered  as  the  primitive  seat  of  the 
passions,*  as  is  done  by  the  greater  number  of  philosophers. 
Of  all  the  feelings  of  man,  the  most  lasting,  the  most  sacred, 
the  most  passionate,  the  least  susceptible  of  injur)'  from  all  the 

* If  we  analysed  the  passions  carefully,  it  would  be  right  to  distinguish 
those  which  are  comaaon  to  all  men,  which  appertain  to  our  physical  wants  and 
to  our  nature,  from  certain  caprices  of  the  mind  which  have  been  honoured 
■with  the  name  of  passions,  as  avarice,  ambition,  erroneous  calculations  which 
should  be  referred  to  mental  derangement,  and  classed  among  tlife  different 
kinds  of  iusanitv. 


OF  SENSATIONS. 


407 

prejudices  of  the  social  state,  maternal  love,  is  surely  not  the  re- 
sult of  any  intellectual  combination,  of  any  cerebral  action:  it  is 
in  the  bowels  (entrailles),  its  source  lies;  thence  it  springs,  and 
all  the  efforts  of  imagination  cannot  attain  it  for  those  who  have 
not  been  blessed  with  a mother’s  name. 

All  passion  springs  from  desire,  and  supposes  a certain  de- 
gree of  exaltation  of  the  intellectual  faculties.  The  shades  of  the 
passions  are  infinite;  they  might  be  all  arranged  by  a systematic 
scale,  of  which  indifference  would  be  the  lowest  gradation,  and 
maniacal  rage  the  highest.  A man,  without  passions,  is  as  im- 
possible to  imagine,  as  a man  without  desires;  yet  we  distin- 
guish as  passionate,  those  whose  will  rises  powerfully  towards 
one  object  earnestly  longed  for.  In  the  delirium  of  the  passions, 
we  are  for  ever  making,  unconsciously,  false  judgments,  of  which 
the  error  is  exaggeration.  A man  recovering  from  a seizure  of 
fear,  laughs  at  the  object  of  his  terror.  Look  at  the  lover  whose 
passion  is  extinct:  freed  at  last  from  the  spell  that  enthralled  him, 
all  the  perfections  with  which  his  love  had  invested  its  object 
are  vanished;  the  illusion  has  passed  away;  and  he  can  almost 
believe  that  it  is  she  who  is  no  longer  the  same,  while  himself 
alone  is  changed;  like  those  maniacs  who,  on  their  return  to  rea- 
son, wonder  at  the  excesses  of  their  delirium,  and  listen,  incre- 
dulously, to  the  relation  of  their  own  actions.  The  ambitious 
man  feeds  on  imaginations  of  wealth  and  power.  He  who  hates, 
exaggerates  the  defects  of  the  object  of  his  hatred,  and  sees 
crimes  in  his  lightest  faults. 

The  affections  of  the  soul,  or  the  passions,  whether  they  come 
by  the  senses,  or  some  disposition  of  the  vital  organs  favour 
their  birth  and  growth,  may  be  ranged  in  two  classes,  according 
to  their  effects  on  the  economy.  Some  heighten  organic  activit}^; 
such  are  joy,  courage,  hope,  and  love:  whilst  others  slacken  the 
motions  of  life;  as  fear,  grief,  and  hatred.  And  others  there  are, 
that  produce  the  two  effects  alternately  or  together.  So  ambi- 
tion, anger,  despair,  pity,  assuming,  like  the  other  passions,  an 
infinite  variety  of  shades,  according  to  the  intensity  of  their 
causes,  individual  constitution,  sex,  age,  &c.  at  times  increase, 
at  times  abate  the  vital  action,  and  depress  or  exalt  the  power  of 
the  organs. 


OF  SENSATIONS. 


408 

The  instances  which  establish  the  powerful  influence  of  the 
passions  on  the  animal  economy,  are  too  frequent  to  need  re- 
citing. Writers,  in  every  department,  furnish  such  as  show, 
that  excess  of  pleasure,  like  excess  of  pain,  joy  too  lively  or  too 
sudden,  as  grief  too  deep  and  too  unexpected,  may  bring  on  the 
most  fatal  accidents,  and  even  death.  Without  collecting,  in  this 
place,  all  the  observations  of  the  sort  with  which  books  swarm, 
I shall  content  myself  with  referring  to  those,  who  have  brought 
together  the  greatest  number  of  facts  under  one  point  of  view; 
as  Haller,  in  his  Physiology;  Tissot,  in  his  Treatise  on  Diseases 
of  the  Nerves;  Lecamus,  in  his  work  on  Diseases  of  the  Mind; 
Bonnefoy,  in  a paper  on  the  Passions  of  the  Soul,  inserted  in 
the  fifth  volume  of  the  Collection  of  Prizes,  adjudged  by  the 
Academy  of  Surgery. 

The  effects  of  the  passions  are  not,  for  their  uniformity,  the 
less  inexplicable.  How,  and  why  does  anger  give  rise  to  mad- 
ness, to  suppression  of  urine,  to  sudden  death?  How  does  fear 
determine  paralysis,  convulsions,  epilepsy,  &c.?  Why  does  ex- 
cessive joy,  a sense  of  pleasure  carried  to  extremity,  produce 
effects  as  fatal,  as  sad  and  afflicting  impressions?  In  what  way 
can  violence  of  laughter  lead  to  death?  Excess  of  laughter  killed 
the  painter  Zeuxis  and  the  philosopher  Chrysippus,  according 
to  the  relation  of  Pliny.  The  conversion  of  the  reformed  of  the 
Cevennes,  under  Louis  XIV,  was  effected  by  binding  them  on 
a bench,  and  tickling  the  soles  of  their  feet,  till,  overpowered  by 
this  torture,  they  abjured  their  creed;  many  died  in  the  convul- 
sions and  immoderate  laughter  which  the  tickling  excited.  A 
hundred  volumes  would  be  insufficient  to  detail  all  the  effects 
of  the  passions  on  physical  man;  how  many  would  it  take  to  tell 
their  history  in  moral  man,  from  their  dark  origin,  through  all 
their  stages  of  growth,  in  the  infinite  variety  of  their  characters, 
and  in  all  their  evanescent  shades! 

The  inquiries  of  physiology  are  directed  to  the  functions  that 
are  carried  on  in  physical  man,  to  the  functions  of  life;  the 
study  of  the  nobler  parts  of  ourselves,  of  those  wonderful  facul- 
ties which  place  our  kind  above  all  that  have  motion  or  life;  in 
a word,  the  knowledge  of  moral  and  intellectual  man,  belongs  to 
the  science  known  by  the  name  of  metaphysics  or  psychology, 
of  analysis  of  the  understanding,  but  better  described  by  that 


OF  SENSATIONS. 


409 


applied  to  it  by  the  writers  of  our  days,  ideology.  On  this  sci- 
ence, you  may  consult,  with  advantage,  the  philosophical  works 
of  Plato  and  Aristotle  among  the  ancients;  of  Bacon,  Hobbes, 
Locke,  Condillac,  Bonnet,  Smith,  Cabanis,  and  Tracy  among 
the  moderns. 

CL  IX.  Of  sleep  and  -waking.  The  causes  of  excitation  to 
which  our  organs  are  exposed  during  waking,  tend  to  increase 
progressively  their  action;  the  pulsations  of  the  heart,  for  in- 
stance, are  much  more  frequent  in  the  evening  than  in  the 
morning,  and  this  motion,  gradually  accelerated,  would  soon  be 
carried  to  a degree  of  activity  incompatible  with  the  continuance 
of  life,  did  not  sleep  daily  temper  this  energy,  and  bring  it 
down  to  its  due  measure.  Fever  is  occasioned  by  long  continued 
want  of  sleep,  and  in  all  acute  diseases,  the  exacerbation  comes 
on  towards  evening;  the  night’s  sleep  abates  again  the  high  ex- 
citation of  power;  but  this  state  of  the  animal  economy,  so 
salutary  and  so  desirable  in  all  sthenic  affections,  is  more  in- 
jurious than  useful  in  diseases,  consisting  chiefly  in  extreme 
debility.  Adynamy  shows  itself,  almost  always,  in  the  morning, 
in  putrid  fevers;  and  petechiae,  a symptom  of  extreme  weakness, 
break  out  during  sleep.  This  state  is,  likewise,  favourable  to  the 
coming  on  and  to  the  progress  of  gangrene,  and  this  is  a patho- 
logical fact  well  ascertained.  In  all  the  cases  I have  mentioned, 
sleep  does  not  improve  the  condition  of  the  j>atients;  a thing 
easy  ta  conceive,  since  it  only  adds  to  accidental  debility,  the 
essential  characteristic  of  the  disease,  weakness,  which  is  also 
its  principal  characteristic. 

Sleep,  that  momentary  interruption  in  the  communication  of 
the  senses  with  outward  objects,  may  be  defined  the  repose  of 
the  organs  of  sense,  and  of  voluntary  motion.  During  sleep,  the 
inward  or  assimilating  functions  are  going  on:  digestion,  ab- 
sorption, circulation,  respiration,  secretion,  nutrition,  are  carried 
on;  some,  as  absorption  and  nutrition,  with  more  energj^  than 
during  waking,  whilst  others  are  evidently  slackened.  During 
sleep,  the  pulse  is  slower  and  weaker,  inspiration  is  less  fre- 
quent, insensible  perspiration,  urine,  and  all  other  humours  de- 
rived from  the  blood,  are  separated  in  smaller  quantity.  Ab- 
sorption is,  on  the  contrary,  very  active;  hence  the  danger  of 
falling  asleep  in  the  midst  of  a noxious  air.  It  is  known.,  that  the 

3 F 


OF  SENSATIONS. 


410 

marshy  effluvia,  which  make  the  Campagna  di  Roma  so  un- 
healthy, bring  on,  almost  inevitably,  intermittent  fevers,  when 
the  night  is  passed  there;  whilst  travellers  who  go  through  with- 
out stopping,  are  not  affected  by  it. 

The  human  body  is  a tolerable  representation  of  the  centri- 
petal and  centrifugal  powers  of  ancient  physics.  The  motion  of 
many  of  the  systems  which  enter  into  its  structure,  is  directed 
from  the  centre  to  the  circumference;  it  is  a real  exhalation  that 
carries  out  the  result  of  the  perpetual  destruction  of  the  organs; 
such  is  the  action  of  the  heart,  of  the  arteries,  and  of  all  the 
secretory  glands.  Other  actions,  on  the  contrary,  take  their  di- 
rection from  the  circumference  to  the  centre;  and  it  is  by  their 
means,  that  we  are  incessantly  deriving  from  the  food  we  take 
into  the  digestive  passages,  from  the  air  which  penetrates  the 
interior  of  the  lungs,  and  covers  the  surface  of  the  body,  the 
elements  of  its  growth  and  repair.  These  two  motions,  in  oppo- 
site directions,  continually  balance  each  other,  prevailing  by 
turns,  according  to  the  age,  the  sex,  the  state  of  sleep  or  waking. 
During  sleep,  the  motions  tend  from  the  periphery  to  the  cen- 
tfe;  (Hipp.)  and  if  the  organs  that  connect  us  with  outward  ob- 
jects are  in  repose,  the  inward  parts  are  in  stronger  exertion. 
Somnus  labor  visceribus.  (^Hipp.)  A man,  aged  forty  years, 
taken  with  a kind  of  imbecility,  remained  about  a year  and  a 
half  at  the  Hospital  of  St.  Louis,  for  the  cure  of  some  scrophu- 
lous  glands;  all  that  long  time  he  remained  constantly  in  bed, 
sleeping  five  sixths  of  the  day,  tortured  with  devouring  hunger,' 
and  passing  his  short  moments  of  waking  in  eating;  his  diges- 
tion was  always  quick  and  easy;  he  kept  up  his  plumpness,  thougii 
the  muscular  action  was  extremely  languid,  the  pulse  very  weak 
and  very  slow.  In  this  man,  who,  to  use  the  expression  of  Bor- 
deu,  lived  under  the  dominion  of  the  stomach,  the  moral  affec- 
tions were  limited  to  the  desire  of  food  and  of  repose.  Oppress- 
ed with  irresistible  sloth,  it  was  never  without  great  difficulty 
that  he  could  be  brought  to  take  the  slightest  exercise. 

Waking  may  be  looked  upon  as  a state  of  effort,  and  of  consi- 
derable expenditure  of  the  sensitive  and  moving  principle,  by 
the  organs  of  sensation  and  of  motion.  This  principle  would 
have  been  soon  exhausted  by  this  uninterrupted  effusion,  if  long 
intervals  of  repose  had  not  favoured  its  restoration.  This  inter- 


OF  SENSATIONS. 


411 

ruption  in  the  exercise  of  the  senses  and  of  voluntary  motion,  is 
of  duration  corresponding  to  that  of  their  exertion.  I have  al- 
ready said,  that  there  are  functions  of  such  essential  importance 
to  life,  that  their  organs  could  be  allowed  but  short  moments  of 
repose:  but  that  these  intervals  are  brought  so  close  to  each 
other,  that  their  time  is  equally  divided  between  activity  and 
repose.  The  functions  which  keep  up  our  connexion  with  out- 
ward objects,  could  not  be  without  the  capacity  of  continuing, 
for  a certain  time,  in  a state  of  equal  activity;  for  it  is  easy  to 
see  how  imperfect  relations,  interrupted  at  every  moment,  would 
have  been;  their  repose,  which  constitutes  sleep,  is  of  equal 
duration. 

The  duration  of  sleep  is  from  a fourth  to  a third  of  the  day; 
few  sleep  less  than  six  hours,  or  more  than  eight.  Children,  how- 
ever, require  longer  sleep,  the  more,  the  nearer  they  are  to  the 
period  of  their  birth.  Old  men,  on  the  contrary,  have  short  sleep, 
light,  and  broken:  as  if,  says  Grimaud,  according  to  Stahl’s  no- 
tions, children  foresaw  that  in  the  long  career  before  them,  there 
were  time  enough  for  performing,  at  leisure,  all  the  acts  of  life, 
while  old  men  near  to  their  end,  felt  the  necessity  of  hurrying 
the  enjoyment  of  a good  already  about  to  escape. 

If  the  sleep  of  a child  is  long,  and  deep,  and  still,  it  is  the  won- 
derful activity  of  the  assimilating  functions  that  makes  it  so,  and 
perhaps  the  habit  itself  of  sleep,  in  which  he  has  passed  the  first 
nine  months  of  his  life,  or  all  the  time  before  his  birth.  In  ad- 
vanced age,  the  internal  functions  grow  languid;  their  organs  no 
longer  engage  the  action  of  the  principle  of  life;  and  the  brain  is 
moreover  so  crowded  with  ideas,  that  it  is  almost  always  kept 
awake  by  them.  Carnivorous  animals  sleep  longer  than  grami- 
nivorous animals,  because  during  waking  they  are  more  in  mo- 
tion, and  perhaps,  too,  because  the  animal  substances  on  which 
they  subsist,  yielding  them  more  nutritious  particles,  from  the 
same  bulk,  they  have  need  of  less  time  for  devouring  their  food 
and  providing  for  their  subsistence.* 

Probably  their  more  powerful  digestion  of  a more  nutritious  fiiod,  bringing 
into  the  system  a more  sudden  accession  of  blood,  oppresses  them  with 
sleep: — a sleep  and  a fulness  of  blood  required  to  recruit  the  powers  that  have 
been  exhausted  by  the  laborious  quest  of  food,  and  by  the  long  continued  en- 
durance of  hunger.  T, 


OF  SENSATIONS. 


412 

Sleep  is  a state  essentially  different  from  death,  to  which  some 
authors  have  erroneously  likened  it.*  It  merely  suspends  that 
portion  of  life,  which  serves  to  keep  up  with  outward  objects  an 
intercourse  necessary  to  our  existence.  One  may  say  that  sleep 
and  waking  call  each  other,  and  are  of  mutual  necessity.  The 
organs  of  sense  and  motion,  weary  of  acting,  rest;  but  there  are 
manv  circumstances  favouring  this  cessation  of  their  activity. 
A continual  excitation  of  the  organs  of  sense  would  keep  them 
continually  awake;  the  removal  of  the  material  causes  of  our 
sensations  tends,  therefore,  to  plunge  us  into  the  arms  of  sleep: 
wherefore  we  indulge  in  it  more  voluptuously  in  the  gloom  and 
the  stillness  of  night.f  Our  organs  fall  asleep  one  after  the  other; 
the  smell,  the  taste,  and  the  sight  are  already  at  rest,  when  the 
hearing  and  the  touch  still  send  up  faint  impressions.  The  per- 
ceptions, awhile  confused,  in  the  end  disappear;  the  internal 
senses  cease  acting,  as  well  as  the  muscles  allotted  to  voluntary 
motion,  whose  action  is  entirely  subject  to  that  of  the  brain. 

Sleep  is  a state,  if  not  altogether  passive,  in  which,  at  least, 
the  activity  of  most  of  the  organs  is  remarkably  diminished, 
and  that  of  some  of  them  completely  suspended.  It  is  erro- 
neously then,  that  some  authors  have  viewed  it  as  an  active 
phenomenon,  and  a function  of  the  living  economy:  it  is  only  a 
mode  or  manner  of  being.  It  is  to  no  purpose  they  have  main- 
tained, that  to  sleep  required  some  measure  of  strength.  Ex- 
cessive fatigue  hinders  sleep,  merely  by  a sense  of  pain  in  all 
the  muscles,  a pain  that  excites  anew  the  action  of  the  brain, 
which  it  keeps  awake,  till  it  is  itself  overpowered  by  sleep. 

Ith  as  been  attempted  to  show  the  proximate  cause  of  sleep. 
Some  have  said  that  it  depends  on  the  collapse  of  the  laminae  of 
the  cerebellum,  which,  as  the)*  conceive,  are  in  a state  of  erection 
during  waking;  and  they  argue  from  the  experiment  in  which 
by  compressing  the  cerebellum  of  a living  animal,  sleep  is  im- 

* To  say  that  sleep  is  the  image  of  death,  that  vegetables  sleep  always,  is 
to  use  an  inaccurate  and  unmeaning  expression.  How  can  plants,  without 
brain  or  nerves,  witliout  organs  of  sense,  motion,  or  voice,  sleep;  when  sleep 
is  nothing  but  the  repose  of  these  organs? 

t The  tissue  of  the  eye-lids  is  not  so  opake,  but  we  may  distinguish  through 
them  light  from  darkness:  accordingly  a lighted  torch,  in  the  room,  hinders  us 
from  sleeping.  For  the  same  reason,  day  succeeding  to  night  awakens  us. 


OF  SENSATIONS. 


413 


mediately  brought  on.«*This  sleep,  like  that  produced  by  com- 
pression  of  any  other  part  of  the  cerebral  mass,  is  really  a state 
of  disease;  and  no  more  natural  than  apoplexy.  Others,  con- 
ceiving sleep,  no  doubt,  analogous  to  this  affection,  ascribe  it  to 
the  collection  of  humours  upon  the  brain,  during  waking.  This 
organ,  sav  they,  compressed  by  the  blood  which  obstructs  its 
vessels,  falls  into  a state  of  real  stupor.  An  opinion  as  unsup- 
ported as  the  other.  As  long  as  the  humours  flow  in  abundance 
towards  the  brain,  they  keep  up  in  it  an  excitement  which  is  al- 
together unfavourable  to  sleep.  Do  we  not  know,  that  it  is 
enough  that  the  brain  be  strongly  occupied  by  its  thoughts,  or 
vividly  affected,  in  any  way,  to  repel  sleep?  Coffee,  spirituous 
liquors,  in  small  quantities,  will  produce  sleeplessness,  by  eli- 
citing the  force  of  circulation,  and  determining  towards  tlie 
brain,  a more  considerable  afflux  of  blood.  All,  on  the  other 
hand,  that  may  divert  this  fluid  towards  another  organ,  «s 
copious  bleedings,  pediluvium,  purges,  digestion,  copulation, 
severe  cold,  or  whatever  diminishes  the  force  with  which  i,t 
is  driven  towards  it,  as  inebriation,  general  debility,  tends  pov/s 
erfully  to  promote  sleep.  In  like  manner,  is  it  observed,  thtt 
while  it  lasts,  the  cerebral  mass  collapses;  a sign  that  tlie  flow 
of  blood  into  it  is  remarkably  lessened.  > 

The  organs  of  the  senses,  laid  asleep,  in  succession,  awake  in 
the  same  manner.  Sounds  and  light  produce  impressions,  con-1 
fused  at  first,  on  the  eyes  and  ears;  in  a little  time,  these  sensaj 
tions  grow  distinct;  we  smell,  we  taste,  we  judge  of  bodies  by 
the  touch.  The  organs  of  motion  prepare  for  entering  into  ac- 
tion, and  begin  to  act,  at  the  direction  of  the  will.  The  causes 
of  waking  operate  by  determining  a greater  flow  of  blood  into 
the  brain:  they  include  all  that  can  affect  the  senses,  as  the  re- 
turn of  light  and  of  noise  with  the  rising  of  the  sun;  at  times, 
they  act  within  us.  Thus,  urine,  fecal  matter,  other  fluids  accu- 
mulated in  their  reservoirs,  irritate  them,  and  send  up,  towards 
the  brain,  an  agitation  which  assists  in  dispelling  slumber.  Ha- 
bit too,  acts  upon  this  phenomenon,  as  on  all  those  of  the  ner- 
vous and  sensitive  system,  with  most  remarkable  influence. 
There  are  many  that  sleep  soundly  amidst  noises  which,  at 
first,  kept  them  painfully  awake.  Whatever  need  he  may  have 
of  longer  repose,  a man  that  has  fixed  the  daily  hour  of  his 


OF  SENSATIONS. 


414 

awaking,  will  awake  every  morning  to  his  hour.  It  is  as  much 
under  the  control  of  the  will.  It  is  enough  to  will  it  strongly, 
and  we  can  awake  at  any  hour  we  choose. 

CLX.  Of  dreams  and  somnambulism.  Although  sleep  implies 
the  perfect  repose  of  the  organs  of  sensation  and  of  motion,  some 
of  these  organs  persist  in  their  activity;  which  obliges  us  to  ac- 
knowledge intermediate  states  betwixt  sleep  and  waking,  real 
mixed  situations,  which  belong,  more  or  less,  to  one  or  to  the 
other.  Let  us  suppose,  for  instance,  that  the  imagination  repro- 
doces,  in  the  brain,  sensations  it  has  formerly  known,  the  intel- 
lect works,  associates  and  combines  ideas,  often  discordant,  and 
sometimes  natural,  brings  forth  monsters,  horrible,  or  fantastic, 
or  ridiculous;  raises  joy,  hope,  grief,  surprise,  or  terror;  and  all 
tlese  fancies,  all  these  emotions  are  recollected  moi'e  or  less  dis- 
taictly,  when  we  are  again  awake,  so  as  to  allow  no  doubt  but 
that  the  brain  has  been  really  in  action,  during  the  repose  of  the 
organs  of  sense  and  motion.  Dreams  is  the  name  given  to  these 
phenomena.  Sometimes  we  speak  in  sleep,  and  this  brings  us  a 
-ittle  nearer  to  the  state  of  waking,  since  to  the  action  of  the 
fe-ain  is  added  that  of  the  organs  of  speech.  Finally,  all  the  re- 
htive  functions  are  capable  of  action,  excepting  the  outward 
senses.  The  brain  acts,  and  determines  the  action  of  the  organs 
(Of  motion  or  speech,  only  in  consequence  of  former  impressions; 
,and  this  state,  which  differs  from  waking,  only  by  the  inaction 
of  the  senses,  is  called  somnambulism. 

On  this  head  we  meet  with  surprising  relations.  Somnambu- 
lists have  been  seen  to  get  up,  dress,  go  out  of  the  house,  open- 
ing and  shutting  carefully  all  the  doors,  dig,  draw  water,  hold 
rational  and  connected  discourse,  go  to  bed  again,  and  awake 
without  any  recollection  of  what  they  had  said  and  done  in  their 
sleep.  This  state  is  always  very  perilous.  For  as  they  proceed 
entirely  upon  former  impressions,  somnambulists  have  no  warn- 
ing from  their  senses  of  the  dangers  they  are  near.  Accord- 
ingly, they  are  often  seen  throwing  themselves  out  of  a win- 
dow, or  falling  from  roofs,  on  which  they  have  got  up,  without 
being  on  that  account  more  dexterous  in  balancing  themselves 
there,  as  the  vulgar  believe,  in  their  fondness  for  the  marvellous. 

Sometimes,  one  organ  of  sense  remains  open  to  impression' 
and  then  you  can  direct,  at  pleasure,  the  intellectual  action. 


OF  SENSATIONS. 


415 


Thus,  you  will  make  him  that  talks  in  his  sleep,  speak  on  what 
subject  you  choose,  and  steal  from  him  the  confession  of  his 
most  secret  thoughts.  This  fact  may  be  cited  in  proof  of  the 
errors  of  the  senses,  and  of  the  need  there  is  to  correct  them 
by  one  another. 

The  condition  of  the  organs  influences  the  subject  of  the 
dreams.  The  superabundance  of  the  seminal  fluid  provokes 
libidinous  dreams;  those  labouring  under  pituitary  cachexies 
will  dream  of  objects  of  a hue  like  that  of  their  humours.  The 
hydropic  dreams  of  waters  and  fountains,  whilst  he  who  is  suf- 
fering with  an  inflammatory  affection,  sees  all  things  tinged  red, 
that  is,  of  the  colour  of  blood,  the  predominant  humour. 

Difficult  digestion  disturbs  sleep.  If  the  stomach,  over-filled 
with  food,  hinders  the  falling  of  the  diaphragm,  the  chest  dilates 
with  difficulty,  the  blood,  which  cannot  flow  through  the  lungs, 
stagnates  in  the  right  cavities  of  the  heart,  and  a painful  sensa- 
tion comes  on,  as  if  an  enormous  weight  lay  upon  the  chest, 
and  were  on  the  point  of  producing  suffocation:  we  awake  with 
a start,  to  escape  from  such  urgent  danger:  this  is  what  we  call 
night-mare,  an  affection  that  may  arise  from  other  causes,  hy- 
drothorax, for  instance,  but  which  always  depends  on  the  diffi- 
cult passage  of  blood  through  the  lungs. 

The  intellectual  faculties  which  act  in  dreams,  may  lead  us 
to  certain  orders  of  ideas,  which  we  have  not  been  able  to  com- 
pass while  awake. 

Thus  mathematicians  have  accomplished  in  sleep,  the  most 
complex  calculations,  and  resolved  the  most  difficult  problems. 
It  is  easily  understood,  how,  in  the  sleep  of  the  outward  senses, 
the  sensitive  centre  must  be  given  up  altogether  to  the  combi- 
nation of  ideas  in  which  it  must  work  with  more  energy.  It  is 
seldom  that  the  action  of  imagination  on  the  genital  organs, 
during  waking,  goes  the  length  of  producing  emission:  nothing 
is  more  common  in  sleep. 

The  human  species  is  not  the  only  one,  that  in  sleep  is  subject 
to  agitations,  which  are  generally  comprehended  under  the  name 
of  dreams:  they  occur  in  animals,  and  most  in  those  whose  na- 
ture is  most  irritable  and  sensible.  Thus  the  dog  and  horse 
dream  more  than  the  ruminating  kinds;  the  one  barks,  the  other 
neighs  in  sleep.  Cows  that  are  suckling  their  calves,  utter  faint 


OF  SENSATIONS. 


416 

lowings:  bulls  and  rams  seem  goaded  by  desires,  which  they 
express  especially,  by  peculiar  motions  of  their  lips. 

After  what  has  been  said  of  sleep  and  dreams,  it  will  not  be 
difficult  to  explain,  why  there  is  so  little  refreshment  of  the 
powers,  from  sleep  that  is  harassed  by  uneasy  dreams.  We 
often  awake,  exceedingly  fatigued  with  the  distress  of  imagi- 
nary dangers,  and  the  efforts  we  have  made  to  escape  them. 

We  have  seen  the  relations  of  man,  with  the  external  world, 
established  by  means  of  peculiar  organs,  which,  through  the  in- 
tervention of  nerves,  all  centre  in  one,  the  chief  and  essential 
seat  of  the  function  of  which  this  chapter  treats.  As  the  pheno- 
mena of  the  sensations  are  brought  about  by  the  intervention  of 
an  unknown  agent,  and  as  like  those  of  electricity  and  magne- 
tism, they  appear  not  to  be  subject  to  the  ordinary  laws  of  mat- 
ter and  motion,  they  have  thown  open  the  widest  field  to  the 
conjectures  of  ignorance,  and  the  inventions  of  quackery.  It  is 
for  their  explanation,  that  the  greatest  abundance  of  theories, 
and  the  wildest,  have  been  devised. 

On  the  23d  of  December,  it  is  not  said  in  what  year,  a physi- 
cian of  Lyons,  M.  Petetin,  was  called  in  to  a young  lady  of  nine- 
teen, sanguine  and  robust.  She  was  cataleptic.  The  Doctor  em- 
ployed various  remedies;  and  among  others,  one  dav  bethought 
himself  of  pushing  over  the  patient  on  her  pillow;  he  himself 
fell  with  her,  half  stooping  upon  the  bed,  and  this  led  him  to 
the  “ discovery  of  the  transport  of  the  senses  in  the  epigastrium, 
to  the  extremity  of  the  fingers  and  of  the  toes.”  I use  his  own 
pompous  and  barbarous  expressions,  in  announcing  his  disco- 
very. Our  Doctor  goes  on  to  tell  with  all  gravity,  how  putting 
a bun  on  the  epigastrium  of  the  patient,  she  perceived  the  taste, 
which  was  followed  by  motions  of  deglutition:  if  his  word  is  to 
be  taken,  hearing,  smell,  taste,  sight  and  touch,  were  all  there: 
the  outward  senses,  being,  for  the  time,  completely  laid  asleep. 
To  give  an  air  of  credibility  to  the  matter,  he  adds,  that  she  saw 
the  inside  of  her  body,  guessed  what  was  in  the  pockets  of  by- 
standers, made  no  mistake  in  the  money  in  their  purses:  but  the 
miracle  was  over,  the  moment  they  lapped  the  objects  in  a silk 
stuff,  a coat  of  wax,  or  interposed  any  other  non-conductor. 
Finally,  to  put  to  proof  the  whole  power  of  faith  in  his  readers, 
M.  Petetin  exclaims,  “ Oh  prodigy  beyond  conception!  was  a 


ON  MOTION. 


thought  formed  in  the  brain  without  any  sign  of  it  in  words! 
the  patient  was  instantly  acquainted  with  it.”*  Further  details 
of  so  incredible  a story  would  be  altogether  superfluous. 

I should  not  have  disturbed  the  book  of  M.  Petetin  from  its 
peaceful  slumber,  among  the  innumerable  pamphlets,  which 
Mesmerism  has  brought  into  the  world,  if  a writer  on  physio- 
logy had  not  been  the  dupe  of  this  mystification,  and  had  not 
proceeded  from  it,  to  write  a long  chapter  on  the  metastases  of 
sensibility. 

If  we  should  be  so  unfortunate  as  to  be  reproached  by  the 
lovers  of  the  marvellous,  with  pushing  scepticism  too  far,  we 
must  make  answer:  that  M.  Petetin  is  the  sole  witness  of  his 
miracle:  that  it  is  impossible,  from  his  relation,  to  know  when 
or  on  whom  the  prodigy  took  place;  and  that  this  zealot  of  mag- 
netism might  have  invented  this  story  to  confound  the  unbe- 
lievers who  ventured  to  turn  into  ridicule  his  system  on  the 
electricity  of  the  human  body. 


CHAPTER  VIII. 

ON  MOTION. 

CLXI.  ^l^HIS  Chapter  will  treat  only  of  the  motion  per- 
formed by  the  muscles  under  the  influence  of  the  will;  they  are 
called  muscles  of  locomotion,  as  it  is  by  means  of  them  that  the 
body  changes  its  situation,  moves  from  one  spot  to  another, 
avoids  or  seeks  surrounding  objects,  draws  them  towards  itself, 
grasps  them,  or  repels  them.  The  internal^  involuntary^  and  or- 
ganic motions,  by  means  of  which  each  function  is  performed, 
have  already  been  investigated  separately. 

The  organs  of  motion  may  be  distinguished  into  active  and 
passive:  the  former  are  the  muscles,  the  latter  the  bones,  and  all 
the  parts  by  which  they  are  articulated.  In  fact,  when  in  con- 
sequence of  an  impression  received  by  the  organs  of  sense,  we 
wish  to  approach  towards  the  object  that  produced  it,  or  to  with- 
draw from  it,  the  muscular  organs,  called  into  action  by  the 


* Ekctrkiti  animale,  1 vol.  8vo.  Lyons,  1808^. 

3 G 


418 


ON  MOTION. 


brain,  contract;  while  the  bones,  which  obey  this  action,  per- 
form only  a secondary  part,  are  passive  and  may  be  looked 
upon  as  levers  absolutely  inert. 

The  muscles  consist  of  bundles  of  fibres,  always,  to  a certain 
degree,  red  in  man:  this  colour,  however,  is  not  essential  to 
them,  since  it  may  be  removed  and  the  muscular  tissue  blanch- 
ed by  maceration  or  by  repeated  washing. 

Whatever  may  be  the  situation,  the  length,  the  breadth,  the 
thickness,  the  form  or  the  direction  of  a muscle,  it  is  formed  of 
a collection  of  several  fasciculi  of  fibres,  enveloped  in  a cellular 
sheath  similar  to  that  which  covers  the  muscle  itself,  and  sepa- 
rates it  from  the  surrounding  parts.  Each  fasciculus  is  formed 
of  the  union  of  a multitude  of  fibres,  so  delicate,  that  anatomy 
cannot  reduce  them  to  their  ultimate  division,  and  that  the 
smallest  distinguishable  fibre  is  still  formed  by  the  juxta  posi- 
tion of  numerous  fibrillse  of  incalculable  minuteness.  As  the  last 
divisions  of  the  muscular  fibre  completely  elude  our  means  of 
investigation,  it  would  be  very  absurd  to  attempt  to  explain  their 
minute  structure;  and  after  the  example  of  Muys  to  write  a 
voluminous  work  on  this  obscure  part  of  physiology.  Shall  we 
say  with  the  above  author,  that  each  distinguishable  fibre  is 
composed  of  three  fibrillse  progressively  decreasing  in  size; 
with  Leeuwenhoek,  that  the  diameter  of  this  elementary  fibre 
is  only  the  hundred  thousandth  part  of  a grain  of  sand;  with 
Swammerdam,  de  Heyde,  Cowper,  Ruysch,  and  Borelli,  that 
this  primitive  fibre  consists  of  a series  of  globular,  rhomboidal 
molecules;  with  Lecat,  that  it  is  nervous;  with  Vieussens  and 
Willis,  that  it  is  formed  by  the  extreme  ramifications  of  arte- 
ries; with  others,  that  it  is  cellular,  tomentous,  &c.  How  is  it 
possible  to  speak,  with  any  degree  of  certainty,  of  the  nature  of 
the  parts  of  a whole  which,  from  its  extreme  minuteness,  eludes 
our  most  accurate  investigations.  To  explain  the  phenomena  of 
muscular  action,  it  is  sufficient  to  conceive  each  fibre  as  formed 
of  a series  of  molecules  of  a peculiar  nature,  united  together  by 
some  unknown  medium,  whether  that  be  oil,  gluten,  or  anj' 
other  substance,  but  whose  cohesion  is  manifestly  kept  up  by^ 
the  vital  power,  since  the  muscles  yield,  after  death,  to  efforts 
by  which,  during  life,  they  would  not  have  been  torn;  and  such 
is  their  tenacity,  that  they  are  very  seldom  ruptured. 


ON  MOTION. 


419 


These  fibres,  which,  when  irritated,  possess,  in  the  highest 
degree,  the  power  of  shortening  themselves,  of  contracting, 
however  minute  one  may  suppose  them,  are  supplied  with  ves- 
sels and  nerves.  In  fact,  though  they  are  neither  vascular  nor 
nervous,  as  may  be  readily  ascertained  by  comparing  the  bulk 
of  the  vessels  and  nerves  which  enter  into  the  structure  of  the 
muscles,  with  that  of  these  organs,  and  by  attending  to  the  dif- 
ference of  their  properties;  each  fibre  receives  the  power  ot  con- 
tracting, from  the  blood  brought  to  It  by  the  arteries,  and  from 
the  fluid  transmitted  from  the  brain  along  the  nerves.  A cellu- 
lar sheath  surrounds  these  fibrillse  (and  the  nerves  and  vessels 
perhaps  terminate  within  it),  others  unite  them  together;  the 
fasciculi  of  fibres  are  inclosed  in  common  sheaths,  and  these 
unite,  in  the  same  manner,  into  masses  varying  in  size,  and  the 
union  of  which  forms  the  muscles;  fat  seldom  accumulates  in 
the  cellular  tissue  which  connects  together  the  smallest  fasci- 
culi; it  collects,  in  small  quantity,  in  the  interstices  of  the  more 
considerable  fasciculi;  lastly,  it  is  in  rather  greater  quantity 
around  the  muscle  itself.  A lymphatic  and  aqueous  vapour 
fills  these  cells,  maintains  the  suppleness  of  the  tissue  and  pro- 
motes the  action  of  the  organ,  which  a fluid  of  more  consistence 
would  have  impeded. 

The  greater  number  of  muscles  terminate  in  bodies,  in  gene- 
ral round,  of  a brilliant  white  colour,  that  forms  a striking  con- 
trast with  the  red  colour  of  the  muscular  flesh,  into  which  one 
of  their  extremities  is  imbedded,  while  the  other  extremity  is 
attached  to  the  bone  and  is  lost  in  the  periosteum,  though  the 
tendons  are  quite  distinct  from  it.  The  tendons  are  formed  by 
a collection  of  longitudinal  and  parallel  fibres;  their  structure  is 
more  compact  than  that  of  the  muscles;  they  are  harder  and  ap- 
parently receive  neither  nerves  nor  vessels;  they  consequently 
possess  but  a very  inferior  degree  of  vitality;  hence  they  are  fre- 
quently ruptured  by  the  action  of  the  muscles.  The  muscular 
fibres  are  implanted  on  the  surface  of  the  tendinous  cords, 
without  being  continuous  with  the  filaments  forming  the  lat- 
ter; they  join  them  in  a different  manner,  and  at  angles  more 
or  less  obtuse. 

The  tendons,  in  penetrating  Into  the  fleshy  part  of  the  mus- 
cles, expand,  become  thinner,  and  form  thus  the  internal  apo= 


ON  MOTION. 


420 

neuroses.  The  external  aponeuroses,  independent  of  the  ten- 
dons, though  the  same  in  structure,  differ  from  them  only  in 
the  thinness  and  greater  surface  of  the  planes  formed  by  their 
fibres.  At  one  time  they  cover  a portion  of  the  muscle  to  which 
they  belong;  at  another,  they  surround  the  whole  limb,  furnish- 
ing points  of  insertion  to  the  muscles;  they  prevent  the  muscles 
and  their  tendinous  cords  from  being  displaced;  in  a manner, 
direct  their  action  and  increase  their  power,  in  the  same  way  as 
a moderately  tight  girdle  adds  to  the  power  of  an  athlete. 

We  cannot  admit,  with  Pouteau,  that  the  muscles  of  the  limbs, 
though  applied  to  the  bones  by  aponeurotic  coverings,  can  be- 
come displaced,  so  as  to  form  herniae.  When  they  contract  in  a 
wrong  position,  some  fibrillae  are  torn,  and  this  gives  rise  to 
most  of  those  momentary  and  very  sharp  pains  called  cramp.  I 
have  at  present  before  me,  the  case  of  a young  girl,  in  whom 
the  aponeurosis  of  the  leg,  exposed  in  consequence  of  an  exten- 
sive ulceration,  exfoliated  from  the  middle  and  fore  part  of  the 
limb  to  the  instep.  This  exfoliation  was  accompanied  by  a dis- 
placement of  the  tibialis  anticus,  and  of  the  extensors  of  the  toes; 
the  leg  is  become  deformed,  the  motions  of  extension  of  the  foot 
and  toes,  are  performed  with  difficulty,  and  will  soon  become 
impossible,  when  the  exfoliation  of  the  tendons  follows  that  of 
the  aponeurosis  which  protected  them  from  the  air.  « 

CLXII.  When  a muscle  contracts,  its  fibres  are  corrugated 
transversely,  its  extremities  are  brought  nearer  to  each  other, 
then  recede,  and  again  approach  towards  one  another.  These 
undulatory  oscillations,  which  are  very  rapid,  are  followed  by  a 
slighter  degree  of  agitation;  the  body  of  the  muscle,  swollen  and 
hardened  in  its  decurtation,  has  acted  on  the  tendon  in  which  it 
terminates;  the  bone  to  which  the  latter  is  connected,  is  set  in 
morion,  unless  other  agents,  more  powerful  than  the  muscle 
which  is  in  action,  prevent  its  yielding  to  that  impulse.  Such 
are  the  phenomena  exhibited  by  the  muscles  exposed  in  a living 
animal  or  in  man,  when  their  contractions  are  brought  on  by  the 
application  of  a stimulus.  But  these  contractions,  determined  by 
external  causes,  are  never  so  strong  or  instantaneous,  as  those 
which  are  determined  by  the  will,  in  a powerful  and  sudden 
manner.  When  an  athletic  man,  reduced  by  illness,  powerfully 
contracts  the  biceps  muscle  of  the  arm,  this  muscle  is  seen  to 


ON  MOTION. 


421 

swell  suddenly,  to  stilFen,  and  to  continue  motionless  in  that 
state  of  contraction,  as  long  as  the  cerebral  influence,  or  the  act 
of  the  will,  which  determines  it,  lasts. 

Though  the  muscles  manifestly  swell  in  contracting,  and 
though  the  limbs  are  confined  by  the  ligatures  applied  round 
them,  the  whole  bulk  of  the  contractile  organ  diminishes;  it 
loses  in  length,  more  than  it  gains  in  thickness.  This  is  proved 
by  Glisson’s  experiment,  which  consists  in  immersing  the  arm 
in  a vessel  filled  with  a fluid,  which  sinks  when  the  muscles  act. 
We  cannot,  however,  estimate  the  diminution  of  bulk,  by  the 
degree  in  which  the  fluid  sinks,  since  that  effect  is,  in  part, 
owing  to  the  collapse  of  the  layers  of  the  adipose  tissue,  which 
is  compressed  in  the  muscular  interstices. 

A sound  state  of  the  vessels  and  nerves,  distributed  to  mus- 
cles, is  indispensable  to  their  contraction.  If  the  free  circulation 
of  the  blood  or  of  the  nervous  fluid  is  prevented,  by  tying  the 
arteries  or  nerves;  if  the  return  of  the  blood,  along  the  veins,  is 
prevented,  by  applying  a ligature  to  these  vessels,  the  muscles 
will  be  completely  palsied.  By  dividing  or  tying  the  nerves,  the 
action  of  the  muscles  to  which  they  are  distributed,  is  suddenly 
interrupted.  The  same  effect  may  be  produced  by  intercepting 
the  course  of  the  arterial  blood,  though  in  a less  rapid  and  in- 
stantaneous manner;  and  it  is  very  remarkable,  that  it  is  equal- 
ly necessary  that  the  veins  should  be  as  sound  as  the  arteries,  to 
enable  muscular  action  to  take  place.  Kaaw  Boerhaave  ascer- 
tained, by  actual  experiment,  that  when  a ligature  is  applied  to 
the  vena  cava,  above  the  iliacs,  paral3^sis  of  the  lower  extremi- 
ties is  brought  on,  as  when  the  aorta  is  tied,  as  was  done  by 
Steno  in  the  same  situation.  And  this  is  a further  proof  of  what 
we  have  said  elsewhere,  of  the  stupefying  qualities  of  the  blood 
which  flows  in  the  veins. 

The  irritability  of  the  muscles  destined  to  voluntary  motions, 
is  proportioned  to  the  size  and  number  of  the  nerves  and  arte- 
ries which  are  distributed  to  their  tissue.  The  tongue,  which,  of 
all  the  contractile  organs,  receives  the  greatest  number  of  cere- 
bral nerves,  is,  likewise,  that  which,  of  all  those  under  the  con- 
trol of  the  will,  has  most  extent,  most  freedom,  and  most  varie- 


422 


ON  MOTION. 


ty  of  motions.*  The  muscles  of  the  larynx,  and  the  intercostals, 
receive  nearly  as  many,  considering  the  smallness  of  these  parts. 

CLXIII.  Of  all  the  hypotheses  applied  to  the  explanation  of 
the  phenomena  of  muscular  contraction,  that  appears  to  me  the 
most  ingenious  and  the  most  probable,  which  makes  it  to  de- 
pend on  the  combinations  of  hydrogen,  of  carbon,  of  azote,  and 
other  combustible  substances  in  the  fleshy  part  of  the  muscle, 
with  the  oxygen  conveyed  with  the  blood  by  the  arteries. 

To  eflfect  this  combination,  it  is  necessary  not  only  that  the 
muscle  be  supplied  with  arterial  blood,  and  that  oxygen  come 
in  contact  with  the  substances  which  it  is'  to  oxydize,  but  it  is 
required  that  a stream  of  nervous  fluid  should  penetrate  through 
the  tissue  of  the  muscle,  and  determine  the  decompositions 
which  take  place;  as  the  electrical  spark  gives  rise  to  the  forma- 
tion of  water,  by  the  combination  of  the  two  gases  of  which  it 
consists.  According  to  this  theory,  first  proposed  by  Girtanner, 
all  the  changes  which  take  place,  during  the  contraction  of  a 
muscle,  the  turgescence,  the  decurtation,  and  the  induration  of 
its  tissue,  its  change  of  temperature,  depend  on  the  reciprocal 
action  of  the  elements  of  the  muscular  fibre,  and  of  the  oxygen 
of  arterial  blood. 

Muscular  flesh  is  harder,  firmer,  and  more  oxydized,  accord- 
ing as  the  animal  takes  much  exercise.  We  well  know  what  a 
diflFerence  there  is,  between  the  flesh  of  wild  and  of  the  domes- 
tic animals;  between  the  flesh  of  our  common  fowl,  and  that  of 
birds  accustomed  to  remain  long  on  the  wing:  in  the  former  it 
is  white,  tender,  and  delicate;  while,  in  the  latter,  it  is  tough, 
stringjf,  dark-coloured,  carbonaceous,  and  of  a very  strong  smell. 
Respiration,  of  which  the  principal  use  is  to  impregnate  arterial 
blood  with  the  oxygen  necessary  to  the  contractions  of  the  mus- 
cular fibre,  is  more  complete,  decomposes  the  greater  quantity 
of  atmospherical  air,  in  those  animals  that  are  naturally  destined 

*It  is  scarcely  necessary  to  repeat,  that  I am  not  speaking  of  those  motions, 
more  or  less  involuntary,  performed  by  muscles  which  receive  their  nerves,  in 
part  or  wholly,  from  the  great  sympathetics.  Though  the  particular  nature  of 
these  nerves  has  a remarkable  influence  on  the  organs  to  which  they  are  dis- 
tributed, we  find  that  the  general  rule  is  almost  without  exceptions;  for  the 
heart  and  diaphragm,  which  hold  the  first  rank  among  the  parts  endowed  with, 
irritability,  receive  a considerable  number  of  vessels  and  nerves. 


ON  MOTION. 


423 


to  most  exertion.  Those  birds  which  support  themselves  in  the 
air  by  powerful  and  frequent  motions,  have  likewise,  the  most 
active  respiration.  Athletes,  who  astonish  us  by  the  develop- 
ment of  their  muscular  organs,  and  by  the  powerful  efforts 
of  which  they  are  capable,  all  have  a very  ample  chest,  a power- 
ful voice,  and  very  capacious  lungs.*  In  running,  as  there  is  a 
considerable  consumption  of  the  principle  of  motion,  we  pant; 
that  is,  we  breathe  in  a hurried  manner,  that  there  may  be  the 
greatest  possible  quantity  of  blood  oxydized,  to  perform  the 
contractions  necessary  to  the  exercise  of  running. 

CLXIV.  Of  the  preponderance  of  the  flexors  over  the  exten- 
sors.] The  extensor  muscles  are,  generally,  weaker  than  the 
flexors;  hence  the  most  natural  position,  that  in  which  all  the 
powers  are  naturally  in  equilibrio,  that  which  our  limbs  assume 
during  sleep,  when  the  will  ceases  to  determine  the  vital  in- 
flux to  the  parts  under  its  control,  that  in  which  we  can  continue 
longest  without  fatigue,  is  a medium  between  flexion  and  exten- 
sion, a real  state  of  semi-flexion. 

Attempts  have  been  made  to  discover  the  cause  of  this  pre- 
ponderance of  the  flexor  muscles  over  their  antagonists.  Accord- 
ing to  Borelli,  the  flexors  being  shorter  than  the  extensors  of 
the  same  articulation,  and  contracting  equally,:):  the  former  must 
occasion  a more  extensive  motion  of  the  limbs,  and  determine 
them  towards  a state  of  flexion.  But  it  is,  in  the  first  place,  in- 
correct to  say,  that  the  flexors  are  shorter  than  the  extensors; 
and,  in  the  next  place,  if  we  are  to  estimate,  by  the  length  of  a 
muscle,  the  extent  of  motion  that  maybe  produced  by  its  action, 
we  ought  not  to  measure  the  whole  of  the  fleshy  part,  nor  to  in- 

• I nevei’  saw  a very  strong  man  that  had  not  broad  shoulders,  which  indi- 
cates a considerable  development  of  the  cavity  of  respiration.  If  there  be 
individuals  that  seem  to  be  exceptions  to  this  general  law,  it  is  that  by  fre- 
quent exercise,  and  by  a laborious  life,  they  have  increased  the  natural  power 
of  their  muscles.  This  increase  is  seldom  universal,  but  almost  always  limited 
to  certain  parts  which  have  been  most  employed;  as  the  arms,  the  legs,  or  the 
shoulders. 

f The  theory  of  the  preponderance  of  the  flexors  is  intirely  my  own,  and 
was  first  proposed  by  me,  in  the  collection  of  memoirs  of  the  Medical  Society 
of  Paris,  for  the  year  VII.  of  the  Republic  (1799). 

+ MuscuU  flexores  ejusdem  articuli  breviores  sunt  extensoribus,  et  utfique 
jeque  contrahunter.  Prop.  130,  de  motu  anitnalium. 


ONT  MOTION. 


424 

dude  in  the  calculation,  the  tendinous  cord  which  terminates  iti 
but  to  consider  the  length  of  its  fibres,  on  which  depends  entire- 
ly the  extent  of  motion  produced  by  its  contractions. 

The  degree  of  decurtation  of  which  a muscle  is  capable,  is 
always  proportioned  to  the  length  of  its  fleshy  fibres,  as  is  the 
power  of  contraction  to  the  number  of  the  fibres.  Nuw,  if  the 
fibres  of  the  flexors  are  in  greater  number  than  those  of  the  ex- 
tensors, it  follows  as  a necessary  consequence,  that  the  limbs 
will  be  brought  into  a state  of  flexion,  when  the  principle  of  mo- 
tion shall  be  distributed  to  them  in  an  equal  quantity;  and  even 
though  the  number  of  fibres  should  be  the  same  in  the  flexors 
and  extensors,  the  limbs  would  still  be  in  a state  of  flexion,  if  the 
fibres  of  the  former  being  longer,  they  made  the  parts  move 
through  a greater  space. 

If  we  examine  the  different  parts  of  the  body,  the  articula- 
tions of  the  limbs,  and  especially  of  the  knee,  the  knowledge  of 
which  is  of  the  highest  importance  in  understanding  the  theory 
of  standing,  it  will  be  seen  that  the  flexor  muscles  exceed  the 
extensors,  in  the  number  and  length  of  their  fleshy  fibres.  If  we 
compare  the  biceps  cruris,  the  semi-tendinosus,  the  semi-raem- 
branosus,  the  rectus  internus,  the  sartorius,  the  gemelli,  the 
plantaris,  and  the  popliteus,  which  all  concur  in  the  flexion  of 
the  legs,  to  the  triceps  cruris  and  to  the  rectus,  which  extend  the 
leg,  we  shall  readily  understand  that  the  fibres  of  these  last  are 
much  shorter,  and  in  smaller  number.  Those  of  the  sartorius 
and  rectus  internus,  are  the  longest  of  all  the  muscles  employed 
in  voluntary  motion;  the  fibres  of  the  posterior  muscles  of  the 
limb,  are  not  inferior  in  length  to  the  fibres  of  the  muscles  at  the 
fore  part. 

Besides,  the  flexor  muscles  are  inserted  into  the  bones  which 
they  are  to  move,  farther  from  their  centre  of  motion.  In  fact, 
if  the  insertion  of  the  semi-membranosus  is  situated  nearly  at 
the  same  height,  the  sartorius,  the  rectus  internus,  the  semi-ten- 
dinosus, the  biceps,  and  the  popliteus,  are  inserted  lower  than 
the  extensors  of  the  leg.  But  this  difference  is  particularly  ob- 
servable in  the  plantaris  and  gemelli,  which  terminate  at  the 
greatest  possible  distance  from  the  centre  of  motion,  and  which 


ON  MOTION. 


425 


act  with  a very  long  lever*;  lastly,  most  of  these  muscles  de- 
part much  more  than  the  extensors,  from  a parallel  direction  to 
the  bones  of  the  leg.  We  all  know  the  curved  line  of  the  course 
of  the  sartorius,  of  the  rectus  internus,  and  semi-tendi  nosus,  by 
which  the  angle  of  their  insertion  becomes  more  favourable. 

The  flexor  muscles,  which,  on  their  being  first  called  into 
action,  are  nearly  parallel  to  the  levers  which  they  are  to  move, 
tend  to  become  perpendicular  to  them,  in  proportion  as  the  mo- 
tion of  flexion  is  carried  on.  Thus,  the  brachialis,  the  biceps 
brachii,  and  the  supipator  longus,  the  mean  line  of  direction  of 
which  is  nearly  parallel  to  that  of  the  bones  of  the  fore  arm, 
when  the  flexion  of  this  limb  commences,  become  oblique,  then 
perpendicular  to  this  bone,  and  at  last  form  with  it  the  angle 
most  favourable  to  their  action.  The  same  applies  to  the  flexors 
of  the  leg;  the  angle  of  their  insertion  becomes  greater,  the  more 
it  bends  on  the  thigh.  The  extensors,  on  the  contrary,  are  in  the 
most  favourable  state  for  action,  at  the  moment  when  their  con- 
traction begins;  in  proportion  as  the  extension  goes  <'n,  they 
have  a tendency  to  become  parallel  to  the  levers  which  they  set 
in  motion;  their  action  even  ceases  before  the  parallelism  is 
complete  at  the  elbow,  by  the  resistance  of  the  olecranon,  and 
at  the  knee,  by  the  numerous  ligaments,  and  by  the  tendons 
situated  towards  thd  posterior  part  of  the  articulation. 

The  flexor  muscles  have,  therefore,  fibres  of  greater  length 
and  more  numerous  than  those  of  the  extensors.  They  are  in- 
serted into  the  bones,  at  a greater  distance  from  the  centre  of 
their  motion,  at  an  angle  less  acute,  and  which  increases  in  size 
as  the  limbs  bend.  The  union  of  these  causes  gives  to  the  limbs 
their  superior  power,  and  the  greater  range  of  motion  in  these 
muscles,  is  a consequence  of  the  arrangement  of  the  articulating 
surfaces,  which  almost  all  incline  towards  the  side  of  flexion. 

This  preponderance  of  the  flexor  muscles,  varies  according 
to  the  different  periods  of  life;  in  the  foetus,  the  parts  are  all  bent 
very  considerably;  this  convolution  of  the  young  animal,  may 

• We  maj',  in  this  respect,  compare  the  gemelli  to  the  supinator  longus,  the 
use  of  which  is  not  limited,  as  was  shown  by  Heister,  to  the  supination  of  the 
hand,  but  which  is,  likewise,  a flexor  of  the  fore  arm,  and  acts  the  more 
powerfully,  as  its  inferior  insertion  is  at  a greater  distance  from  the  elbow 
joint,  and  as  its  fibres  are  the  longest  of  all  those  of  the  muscles  of  the  upper 
extremity. 

3 H 


426 


ON  MOnON, 


be  perceived  from  the  earliest  period  of  gestation,  when  the  eni 
bryo,  of  the  size  of  a French  bean,  and  suspended  by  the  um- 
bilical cord,  floats  in  the  midst  of  the  liquor  amnii,  in  a cavity 
in  which  it  is  more  and  more  confined,  as  it  approaches  to  the 
period  of  its  birth.  This  excessive  flexion  of  the  parts,  which 
was  required  to  enable  the  produce  of  conception  to  accommodate 
itself  to  the  elliptical  shape  of  the  uterus,  concurs  in  giving  to 
the  muscles  which  produce  it,  the  superiority  which  they  retain 
during  the  remainder  of  life.  The  new-born  child  preserves,  in 
a very  remarkable  manner,  the  habits  of  gestation;  but,  in  pro- 
portion as  it  grows,  it  straightens  its  body,  and,  by  frequent 
attempts  to  stretch  itself,  shows  that  a just  proportion  is  about 
to  take  place  between  the  muscular  powers.  When  the  child 
becomes  capable  of  standing  erect,  abandoned  to  its  own  powers, 
all  its  parts  are  in  a state  of  semi-flexion;  it  staggers,  and  is  un- 
steady on  its  feet.  Towards  the  middle  of  life,  the  preponder- 
ance of  the  flexors  over  the  extensors  becomes  less  apparent;  a 
man  enjoys  fully  and  completely  his  power  of  locomotion;  but, 
as  he  advances  in  years,  this  power  forsakes  him;  the  extensor 
muscles  gradually  return  to  the  state  of  comparative  debility  of 
infancy,  and  become  incapable  of  supporting  the  body  in  a fixed 
and  permanent  manner. 

CLXV.  The  state  of  our  limbs,  during  sleep,  approaches  to 
that  of  the  foetus,  which,  according  to  Buffon,  may  be  consider- 
ed to  be  in  a profound  slumber.  The  cessation  of  sleep  is  at- 
tended in  man,  as  well  as  in  most  animals,  by  frequent  stretch- 
ings. We  extend  our  limbs  forcibly,  to  give  to  the  extensors 
the  tone  which  they  require  during  the  state  of  waking*.  Bar- 
thez  accounts,  in  the  same  way,  for  the  manner  in  which  the 
cock  announces  his  waking,  by  crowing  and  flapping  his  wings. 

It  may  happen,  in  consequence  of  a morbid  determination  of 
the  vital  principle,  that  our  limbs  may  remain  in  a state  of  ex- 
tension during  sleep.  Hence  Hippocrates  recommends,  that  the 
state  of  the  limbs  be  carefully  attended  to  while  the  patient 
sleeps;  for,  as  he  observes,  the  further  that  condition  is  from 

* Haller  thinks  that  these  extensions  are  intended  to  relieve  the  uneasy  sen- 
sations occasioned  by  a long’  continued  flexion.  .Aunc  quidein  hornines  et  ani- 
malia  extendimt  nrtus,  quod  iis  fere  confexis  donniant,  et  ex  eo  fterpetuo  situ,in 
musciilis  sensus  incommodus  oriatur,  quern,  extemione  tollunt,  {phenomena  exper- 
ghcentium.)  JElemetua  Physiologic,  \om.  V.  p.  621. 


ON  MOTION. 


427 

the  natural  state,  the  greater  the  danger  to  be  apprehended  of 
the  patient’s  life.  In  certain  nervous  diseases,  characterized  by 
a manifest  aberration  in  the  distribution  of  the  vital  power,  a 
continued  state  of  extension  must  be  considered  a symptom 
highly  dangerous;  I have  had  several  times  occasion  to  observe, 
that  in  cases  of  wounds  attended  with  convulsions  and  tetanus, 
these  alarming  affections  were  announced  by  the  permanent  ex- 
tension of  the  limbs  during  sleep,  before  a difficulty  of  moving 
the  jaw  could  give  rise  to  any  apprehension  of  their  approach. 

Disease  and  excesses  of  all  kinds,  occasion  in  the  extensor 
muscles,  a relative  weakness  that  is  very  remarkable;  hence  we 
see  convalescents,  and  those  who  have  been  addicted  to  volup- 
tuousness, walk  with  bending  knees;  the  more  so  as  their  de- 
bility is  greater,  and  as  the  force  of  the  extensors  is  more  com- 
pletely exhausted.  The  flexion  of  the  knees  is  then  limited  by 
that  condition,  in  which  the  tendons  of  the  extensors  of  the  leg 
act  on  the  tibia,  at  an  angle  sufficiently  great  to  make  up  for  their 
diminished  energy.  There  exists  a condition  of  the  animal  eco- 
nomy, in  which  all  the  muscular  organs  appear  wearied  with 
exertion,  and  the  limbs  assume  indifferently  any  position.  In 
this  state,  which  is  always  a very  serious  one,  as  it  indicates  an 
almost  complete  want  of  action  in  a system  of  organs  whose 
functions  are  absolutely  essential  to  life,  a state  to  which  physi- 
cians have  given  the  name  of  prostration^*  the  limbs,  if  unsup- 
* It  is  from  a knowledge  of  the  strength  of  his  patient,  that  the  physician, 
in  the  treatment  of  disease,  deduces  the  most  instructive  indications.  It  seems 
to  me  that  we  ought  to  endeavour  to  characterize,  by  specific  terms,  the  diffe- 
rent states  of  animal  adynamia  in  different  diseases.  Our  language,  less  fruit- 
ful in  imagery  than  the  ancient  languages,willnot  easily  furnish  these  charac- 
teristic denominations,  so  useful  in  a science  which  should  paint  objects  in 
their  truest  colours,  in  terms  most  approaching  to  nature.  It  will,  therefore, 
be  necessary  to  have  recourse  to  the  Greek  and  Latin  languages,  and,  perhaps, 
to  give  the  preference  to  the  latter,  which  is  generally  understood  by  those 
who  practice  the  art  of  healing.  The  application  of  this  principle  to  the  diffe- 
rent kinds  of  fever,  will  prove  its  utility,  and  will,  doubtless,  be  an  inducement 
to  extend  it  to  all  the  classes  of  morbid  derangements. 

In  febre  inflammatoria  seu  synocho  simplici  (angeio-")  _ 

tenica)  ^ n i. 

In  febre  biliosa  seu  ardente  (raeningo-gastrica)  Fractura  virium- 

In  febre  pituitosa,  seu  morbo  mucoso  (adenomeningea)  Languor  virium. 

In  febre  putrida  (adynamica)  Prosiratio  virium. 

In  febribus  malignis  seu  atactis  Ataxia  virium. 

In  febre  pestilentiall  (adeno-nervosa)  Sideratio  virium. 

TLs 


ON  MOTION. 


428 

ported,  fall  of  their  own  weight,  as  if  they  were  palsied;  the 
trunk  is  motionless  and  supine.  The  patient  is  incapable  of 
changing  his  attitude,  and  yielding  to  the  weight  of  his  body, 
sinks  on  the  inclined  plane  formed  by  the  bed,  and  seems  very 
heavy  to  those  who  may  attempt  to  raise  him,  because  from  his 
helplessness,  he  requires  to  be  moved  as  an  inert  substance. 

CLXVI.  Of  the  power  of  the  muscles;  of  the  mode  of  estimating 
that  power.  The  actual  power  of  the  muscles  is  immensely 
great,  seems  to  grow  in  proportion  to  the  resistance  which  it 
meets  with,  and  can  never  be  estimated  with  precision.  Borelli 
was  guilty  of  a serious  mistake,  in  estimating  the  force  of  a 
muscle  by  its  weight,  compared  to  that  of  another  muscle;  for, 
muscles  may  contain  cellular  tissue,  fat,  tendinous  parts,  and 
aponeuroses,  without  being  the  more  powerful.  Their  strength 
is  always  proportioned  to  the  number  of  their  fleshy  fibres; 
hence,  nature  has  multiplied  those  fibres  in  the  muscles  which 
are  intended  for  powerful  action.  And  in  order  that  this  great 
number  of  muscular  fibres  might  not  add  too  much  to  the  bulk 
of  the  limbs,  they  are  made  shorter,  by  bringing  near  to  each 
other  their  insertions,  which  occupy  extensive  surfaces,  whether 

Tlip  first  term,  which  is  easily  turned  into  French,  expresses,  with  much 
precision,  that  condition  in  which  the  living’  system,  far  from  being  deficient 
in  strength,  is  encumbered  by  its  excess,  and  is  oppressed  by  its  own  powers. 
It  might,  with  slight  modifications,  be  applied  to  all  the  kinds  of  phlegmasias 
and  active  hemorrhages. 

The  second  denomination,  not  so  easily  translated,  expresses  the  sense  of 
general  contusion  and  bruise,  of  which  patients,  labouring  under  bilious  fever, 
{meiiingo  gastricu')  com[ilain  all  over  their  limbs. 

T liis  sensation  is,  likewise,  it  is  true,  experienced  in  pituitary  fever;  but  this 
is  more  particularly  characterized  by  languor  and  loss  of  strength.  The  same 
is  to  be  observed  in  many  patiems  of  a phlegmatic  temperament. 

The  prostration,  which  is  so  remarkable  a character  of  putrid  fevers,  and  in 
consequence  of  which  they  are  called  adynamic,  is  easily  recognized  by  the 
total  cessation,  or  by  an  impaired  condition  of  all  the  functions  performed  by 
muscular  organs;  as  voluntary  motion,  respiration,  circulation,  digestion,  the 
excretion  of  urine,  &.c. 

The  disordered  condition  ofthe  vital  powers  characterizes  the  ataxis;  there 
is  considerable  irregularity  in  these  fevers,  with  a very  anomalous  course  of 
symptoms.  In  this  point  of  view,  one  might  compare,  it  to  several  kinds  of  ner- 
vous disorders. 

Lastly,  the  word  sideration  appears  to  me  to  express,  very  forcibly,  that 
sudden  and  deep  stupor  which  overwhelms  patients  seized  with  the  plague  of 
the  East. 


ON  MOTION. 


429 


aponeurotic  or  osseous.  We  may,  in  general,  judge  of  the  power 
of  a muscle  bv  the  extent  of  the  surfaces  to  which  its  fleshy 
fibres  are  attached;  thus,  the  gemelli  and  the  soleus  have  short 
compressed  fibres,  and  lying  obliquely  between  two  large  apo- 
neuroses. 

If  the  force  with  which  a muscle  contracts,  is  proportioned  to 
the  number  of  its  fibres,  the  degree  of  decurtation  of  which  it  is 
capable,  and  consequently,  the  range  of  motions  which  it  can 
communicate  to  the  limbs,  are  proportioned  to  the  length  of  the 
same  fibres.  Thus,  the  sariorius,  whose  fibres  are  longer  than 
any  in  the  human  body,  is  also  capable  of  most  contraction,  and 
performs  the  most  considerable  motions  of  the  leg.  It  is  impos- 
sible to  fix  any  precise  limits  to  the  decurtation  of  every  parti- 
cular muscular  fibre;  for,  if  the  greater  part  of  the  long  muscles 
of  limbs  lose  little  more  than  a third  of  their  length  in  con- 
tracting, the  circular  fibres  of  the  stomach,  which  in  its  greatest 
dilatation  form  circles  nearly  a foot  in  diameter,  may  contract 
to  such  a degree,  when  this  organ  has  been  long  empty,  as  to 
form  rings  of  scarcely  an  inch  in  circumference.  In  cases  of  ex- 
treme elongation  or  constriction,  does  the  change  that  takes 
place,  affect  the  molecules  that  form  the  muscular  fibre,  or  the 
substances  which  connect  them  together;  or  does  it  affect,  at 
once,  both  the  fibre  and  the  parts  by  which  these  fibres  are 
united  together? 

However  great  the  power  of  the  muscles  maybe,  a great  part 
of  this  power  is  lost,  from  the  unfavourable  disposition  of  our 
organs  of  motion;  the  muscular  powers,  almost  always  parallel 
to  the  bones  which  they  are  to  move,  act  with  the  more  disad- 
vantage on  these  levers,  as  the  mean  line  of  their  direction  is 
further  from  the  perpendicular,  and  is  nearly  parallel  to  them. 

The  greater  part  of  muscles  are,  besides,  inserted  in  the  bones, 
very  near  their  articulations,  or  the  centre  of  motion,  and  move 
them  as  levers  of  the  third  kind,  that  is,  are  always  placed  be- 
tween the  fulcrum  and  the  resistance;  by  multiplying  thus,  in 
the  animal  machine,  the  levers  of  the  third  kind,  nature  has  lost 
in  power,  but  has  gained  in  strength;  for,  in  this  kind  of  lever, 
the  power  moves  through  a very  small  space,  but  makes  the  re- 
sistance move  through  a very  considerable  one.  Besides,  the 
fleshy  fibres  in  shortening  themselves,  do  not  act  directly  on 


430 


ON  MOTION. 


the  tendon  in  which  the  muscle  terminates;  these  fibres  gene- 
rally join,  in  an  oblique  direction,  the  aponeurotic  expansion 
formed  by  the  tendinous  cord,  as  it  penetrates  into  the  muscu- 
lar mass;  now  their  action  being  exerted  in  a direction  more  or 
less  oblique,  is  decomposed,  and  none  is  advantageously  em- 
ployed, but  that  which  takes  place  in  the  direction  of  the  ten- 
don. The  muscles  frequently  pass  over  several  articulations,  in 
their  way  to  the  bone  which  they  are  to  move;  a part  of  their 
power  is  lost  in  the  different  degrees  of  motion  on  each  other, 
of  the  parts  on  which  the  bone  rests,  into  which  the  muscles  are 
inserted.  All  these  organic  imperfections  are  attended  with  an 
enormous  misapplication  of  power,  and  with  a waste  of  the 
greater  part  of  it.  It  has  been  reckoned,  that  the  deltoid  mus- 
cle employs  a power  equal  to  2568  pounds  to  overcome  a re- 
sistance of  50.  We  are  not  to  imagine,  however,  that  there  is  a 
loss  of  2518  pounds;  for  the  deltoid  muscle  acting  both  on  the 
shoulder  and  on  the  arm,  about  one  half  of  its  power  is  employ- 
ed on  each  of  these  parts;  hence  it  is  said,  that  in  estimating  the 
whole  power  of  a muscle,  one  should  double  the  effect  produced 
by  its  contraction,  its  action  being  applied,  at  the  same  time, 
both  on  the  weight  which  it  raises,  or  on  the  resistance  which  it 
overcomes,  and  on  the  fixed  point  to  which  its  other  extremity 
is  inserted. 

If  the  muscles  were  quite  parallel  to  the  bones,  they  would 
be  incapable  of  moving  them  in  any  direction.  On  this  account, 
nature,  has,  as  much  as  possible,  corrected  the  parallelism,  by 
removing,  as  we  shall  see,  in  speaking  of  the  osseous  system, 
the  tendons  from  the  middle  line  of  direction  of  the  bones,  and 
by  augmenting  the  angles  at  which  they  are  inserted  into  them, 
either  by  placing,  along  their  course,  bones  which  alter  their  di- 
rection, as  the  patella  and  the  sesamoid  bones;  by  increasing  the 
size  of  the  articular  extremities  of  the  bones,  or  by  pullies,  over 
which  the  tendons  or  the  muscles  themselves  are  reflected,  more 
or  less  completely,  as  is  the  case  with  the  circumflexus  palati 
and  the  obturator  internus. 

Nature  has  not,  therefore,  neglected  mechanical  advantages 
as  much  as  one  might  be  led  to  imagine,  on  a slight  examina- 
tion of  the  organs  of  motion.  And  if  it  be  considered,  that  in 
the  different  conditions  of  life,  we  do  not  require  strength  sa 


ON  MOTION. 


431 


much  as  rapidity  of  motion,  that  the  power  might  be  gained  by 
increasing  the  number  of  fibres,  while  it  was  impossible  to  ob- 
tain velocity,  by  any  other  means  than  by  employing  a particu- 
lar kind  of  lever,  and  that,  in  short,  to  give  our  limbs  the  most 
advantageous  form,  it  was  necessary  that  the  muscles  should  be 
applied  to  the  bones,  it  will  be  confessed,  that  in  the  arrange- 
ment of  these  organs,  nature,  in  frequently  sacrificing  power  to 
quickness  of  motion,  has  conciliated,  as  much  as  possible,  these 
two  almost  irreconcileable  elements. 

Though  the  lever  of  the  third  kind  is  that  most  frequently 
employed  in  the  animal  economy,  the  two  other  kinds  of  levers 
are  not  altogether  excluded  from  it;  there  are  even  limbs  which 
represent  different  levers,  according  to  the  muscles  which  set 
them  in  motion;  thus,  if  we  take  the  foot  as  an  instance,  it  will 
present  us  with  levers  of  every  kind.  The  foot,  when  raised 
from  the  ground  and  held  up  and  raised  towards  the  leg,  forms 
a lever  of  the  first  kind;  the  fulcrum  is  in  the  articulation  and 
separates  the  power,  which  is  at  the  heel,  from  the  resistance 
which  is  at  the  tip  of  the  foot  that  points  downwards;  if  this 
end  of  the  foot  rest  on  the  ground,  and  if  we  stand  on  tip-toe, 
they  are  changed  into  levers  of  the  second  kind;  the  power  con- 
tinues at  the  heel,  but  the  fulcrum  is  removed  to  the  other  ex- 
tremity of  the  lever,  and  the  resistance  to  the  middle;  and  this 
resistance  is  very  considerable,  since  the  whole  weight  of  the 
body  rests  on  the  articulation  of  the  foot  with  the  leg.  In  stand- 
ing on  tip-toe,  the  muscles  of  the  calf  of  the  leg  become  prodi- 
giously fatigued,  though  their  action  is  assisted  by  the  most  fa- 
vourable lever,*  adapted  to  the  greatest  resistance  which  nature 
can  oppose  to  herself.  Lastly,  the  foot  moves  as  a lever  of  the 
third  kind,  when  we  bend  it  on  the  leg. 

CLXVII.  What  is  called  the  fixed  point  in  the  action  of  mus- 
cular organs,  does  not  always  deserve  that  name.  Thus,  though 
it  may  be  said  very  correctly,  that  the  greater  part  of  the  mus- 
cles of  the  thigh  have  their  fixed  point  in  the  bones  of  the  pelvis, 
to  which  their  upper  extremity  is  attached,  and  though  they 
move  the  femur  on  the  ilia,  which  are  less  moveable;  when  the 

* Of  levers  with  arms  of  unequal  length,  that  of  the  second  kind  is  the  most 
favourable,  since  the  arm  of  the  power  is  uniformly  longer  than  tljat  of  the 
resistance. 


4S2 


ON  MOTION. 


thigh  is  fixed  by  the  action  of  other  muscles,  these  move  the 
pelvis  on  the  thigh,  and  that  which  was  the  fixed  point,  be- 
comes moveable.  The  same  applies  to  the  other  muscles  of  the 
body,  so  that  the  fixed  point  is  merely  that  which,  generally,  is 
a fulcrum  to  the  muscular  action.  This  necessary  fixed  state  of 
one  of  the  bones,  to  which  is  attached  one  of  the  extremities  of 
a muscle  which  we  wish  to  contract,  renders  it  necessary,  in  per- 
forming the  slightest  motion,  that  several  muscles  should  be 
called  into  action,  which  implies  a very  complicated  mechanism. 
Nothing  is  easier  to  prove.  Suppose  a man  stretched  on  the 
ground  or  lying  on  his  back;  if  we  wish  to  raise  his  head,  it  will 
be  necessary  that  his  chest  become  the  fixed  point  of  action  of 
the  sterno  cleido  mastoidei,  whose  office  it  is  to  perform  this 
motidfi.  Now,  in  order  that  the  pieces  forming  this  osseous 
structure  may  remain  motionless,  it  will  be  required,  that  the 
chest  should  be  fixed  b>  the  action  of  the  abdominal  muscles, 
which,  on  the  other  hand,  have  their  fixed  point  in  the  pelvis, 
that  is  itself  fixed  in  its  place  by  the  contraction  of  the  gluiaei 
muscles.  It  was  on  this  principle  that  Winslow  first  suggested, 
that  in  reducing  a hernia,  the  patient  should  be  laid  in  an  hori- 
zontal posture,  with  injunctions  not  to  raise  his  head,  that  the 
abdominal  muscles  being  relaxed,  their  different  openings  might 
yield  more  easily  to  the  reduction  of  the  parts. 

In  case  the  two  opposite  points  to  which  the  extremities  of  a 
muscle  are  attached,  are  equally  moveable,  they  approach  to- 
wards each  other,  during  the  contraction  of  the  muscle,  by 
making  them  move  through  equal  spaces.  These  spaces  would 
not  be  equal,  if  the  mobility  were  different.  Each  muscle  has 
its  antagonist,  that  is,  another  muscle  whose  action  is  directly 
opposed  to  it.  Thus,  the  flexors  balance  the  action  of  the  exten- 
sors, the  adductors  perform  motions  different  from  those  of  the 
abductors.  When  two  antagonizing  muscles  of  equal  power  act 
at  the  same  time,  on  a part  equally  moveable,  in  every  direc- 
tion, the  opposite  powers  neutralize  each  other,  and  the  part  re- 
mains motionless.  If  there  is  a difference  in  the  degree  of  con- 
traction, the  part  is  directed  towards  the  muscle  whose  contrac- 
tion is  the  most  powerful:  if  the  opposition  is  not  direct,  the 
part  follows  a middle  direction,  between  the  two  powers  which 
move  it.  Thus,  the  rectus  externus  muscle  of  the  eye  is  not  an- 


ON  MOTION. 


433 


tagonized  by  the  rectus  inferior;  hence  when  these  two  muscles 
come  to  contract,  at  the  same  time,  the  eye  is  not  carried  down- 
ward or  outward,  but  at  once  downward  and  outward;  it  is  then 
said  to  move  in  the  diagonal  of  a parallelogram,  of  which  the 
sides  are  represented  by  the  muscles  in  action. 

CLX  VIII.  Of  the  nature  of  muscular  fesh.  I shall  not  speak, 
at  present,  of  the  manner  in  which  the  muscles  receive  nourish- 
ment, by  retaining  within  the  meshes  of  their  tissue,  the  fibrina 
which  the  blood  conveys  to  them  in  such  quantity,  that  several 
among  the  ancients  and  moderns  have  called  the  blood,  “ liquid 
flesh;”  an  expression  at  once  forcible  and  correct,  since  all  the 
organs  are  repaired  and  grow,  by  the  solidification  of  its  diffe- 
rent parts.  Haller  first  observed  that  most  of  the  muscular  arte- 
ries were  very  tortuous  in  their  course  to  the  muscles.  This  dis- 
position, w'hich  cannot  fail  to  slacken,  very  considerably,  the 
course  of  the  blood,  favours  the  formation  and  the  secretion  of 
the  fibrous  element  which  the  muscles  appropriate  to  their  own 
substance,  and  to  which  it  bears  so  strong  an  affinity.  Motion 
influences,  in  a very  remarkable  manner,  this  nutritive  secre- 
tion. The  muscles  that  are  most  in  action,  uniformly  acquire 
the  greatest  size  and  strength;  if  left  in  a state  of  complete  in- 
action, they  become  exceedingly  reduced  in  size,  from  the  sus- 
pended secretion  of  the  fibrinous  principle.  Muscular  motion 
promotes,  very  remarkably,  the  circulation  and  the  distribution 
of  all  the  fluids.  The  flow  of  venous  blood,  after  bleeding,  is 
never  copious,  unless  the  muscles  of  the  fore  arm  are  made  to 
contract,  by  making  the  patient  hold  the  lancet  case,  and  de- 
siring him  to  move  it  round  in  his  hand. 

The  chemical  nature  of  the  muscular  fibre  is  nearly  the  same 
as  that  of  the  fibrina  obtained  from  the  blood.*  Like  the  latter, 
it  contains  a great  quantity  of  azote,  and  is,  consequently,  very 
much  animalized  and  exceedingly  putrescent.  It  is  from  mus- 
cular flesh,  that  M.  Berthollet  obtained,  in  considerable  quan- 

* Nothing  can  prove,  in  a more  complete  manner,  the  essential  difference 
between  the  fleshy  part  of  muscles  and  their  tendinous  and  aponeurotic  parts, 
than  the  chemical  analysis  of  these  organs.  The  tendons  and  aponeuroses  may 
be  completely  resolved  into  gelatine,  by  long  boiling,  which,  on  the  contrary, 
parches  the  muscular  flesh,  by  exposing  the  fibrina,  in  consequence  of  the  melt- 
ing of  the  fat  of  the  cellular  tissue,  and  of  the  albuminous  juices  in  which  it  is 
enveloped. 

3 I 


434 


ON  MOTION, 


tity,  the  peculiar  animal  acid,  called  bv  that  chemist,  the  zoonic 
acid.  Lastly,  the  element  of  the  blood,  b)’  means  of  which  the 
muscular  flesh  is  repaired,  fibrina  is  already  imbued  with  vital 
properties,  even  while  it  yet  flows  in  a state  of  combination 
with  the  other  parts  of  the  fluid.  This  fibrina,  extracted  from 
the  blood  and  subjected  to  the  galvanic  influence,  is  distinctly 
seen  to  quiver  and  contract  under  that  influence.  At  what 
period  docs  this  substance  acquire  the  power  of  contracting?  It 
is,  doubtless,  at  the  moment  when  it  becomes  organized,  in 
passing  from  the  liquid  to  the  solid  state.  What  relation  does 
there  exist  between  the  organization  of  matter  and  the  vital 
properties  with  which  it  is  endowed?  This  question  cannot  be 
answered,  in  the  present  state  of  our  physiological  knowledge. 

CLXIX.  A professor  of  anatomy  in  the  University  of  Bo- 
logna, Galvani,  was  one  day  making  experiments  on  electricity. 
In  the  laboratory,  not  far  from  the  machine,  lay  some  skinned 
frogs,  of  which  the  limijs  were  convulsed  every  time  a spark 
was  taken.  Galvani,  struck  with  the  phenomenon,  made  it  a 
subject  of  inquiry,  and  found  that  metals,  applied  to  the  nerves 
and  to  the  muscles  of  these  animals,  determined  quick  and 
strong  contractions,  when  they  were  disposed  in  a certain  man- 
ner. He  gave  the  name  of  Animal  Electricity  to  this  set  of  new 
phenomena,  from  the  analogy  he  thought  he  perceived  between 
its  effects  and  those  of  electricity.  The  discovery  was  made 
public:  many  scientific  men,  chiefly  those  of  Italy,  and  Volta 
among  others,  were  eager  to  make  additions  to  the  labours  of 
the  inventor.  Th^  IMedical  Society  of  Edinburgh  thought  it 
right  to  take  this  point  o'  physiology  as  the  subject  of  one  of  its 
annual  prizes,  which  was  adjudged  to  the  work  of  Professor 
Cret  e of  Mentz,  in  which  the  term  metallic  irritation  {irrita- 
mentum  metallonim)  is  substituted  to  that  of  animal  electricity. 
This  new  expression  is  essentially  bad,  since  it  implies  that 
irritation  by  metals  can  alone  determine  the  galvanic  pheno- 
mena, when  charcoal,  water,  and  many  other  substances  pro- 
duce them  as  well.  The  term  of  animal  electricity  has  been  also 
laid  aside,  notwithstanding  the  great  analogy  between  the  ef- 
fects of  electricity  and  those  of  galvanism,  and  this  last  name 
has  been  preferred,  which  applying  equally  to  the  whole  of 
the  phenomena,  immortalizes  the  name  of  the  first  observer. 


N 


ON  MOTION. 


435 

To  produce  the  galvanic  phenomena,  it  is  necessary  to  esta- 
blish a communication  between  two  points  of  a series  of  ner- 
vous and  muscular  organs.  In  this  way,  there  is  formed  a cir- 
cle, of  which  one  arc  is  composed  of  the  animal  parts  that  are 
subjected  to  the  experiment,  while  the  other  arc  is  represented 
by  the  instruments  of  excitation,  which  consist  commonly  of 
several  pieces,  some  of  them  placed  under  the  animal  parts, 
and  called  supports,  and  the  others,  by  which  the  communica- 
tion with  these  is  established,  called  communicators. 

To  form  a complete  galvanic  circle,  take  the  thigh  of  a frog 
stripped  of  its  skin,  detach  the  crural  nerve  down  to  the  knee, 
and  apply  it  on  a plate  of  zinc;  let  the  muscles  of  the  leg  lie  on 
a plate  of  silver,  then  complete  the  arc  of  excitation  and  the 
galvanic  circle,  b}'  establishing  a communication  between  the 
two  supports  with  an  iron  wire,  or  copper,  tin,  or  lead:  at  the 
moment  of  touching  the  two  supports  with  the  conductor,  a 
part  of  the  animal  arc  formed  by  the  muscles  of  the  leg  will  be 
convulsed.  Although  this  arrangement  of  the  animal  parts,  and 
of  the  galvanic  instruments,  is  the  one  most  favourable  to  the 
production  of  these  phenomena,  there  is  room  for  varying  a good 
deal  the  composition  of  the  animal  arc  and  the  arc  of  excitation. 
Thus,  you  obtain  contractions,  by  placing  the  two  supports  under 
the  nerve,  and  leaving  the  muscles  without  the  galvanic  circle; 
which  proves,  that  the  nerves  essentially  constitute  the  animal 
arc.  To  conclude,  the  galvanic  circle  may  be  entirely  animal: 
for  this  purpose  take  a very  lively  frog,  that  it  is  to  say,  one  en- 
joying strong  contractility:  after  insulating  the  lumbar  nerves, 
present  these  nerves  to  the  thigh  of  the  frog;  at  the  moment  of 
contact,  the  limb  will  be  convulsed.  Professor  Aldini  is  the 
first  author  of  this  experiment,  which  is  really  one  of  the  most 
curious,  as  it  leads  more  directly  to  the  explanation  of  the  in- 
fluence of  nerves  on  muscular  organs. 

There  is  no  need  that  the  nerves  be  untouched  to  allow  the 
contractions,  they  are  observed  when  these  organs  are  tied,  or 
cut,  provided  there  be  simple  contiguity  between  the  two  ends 
made  by  the  section.  This  shows  that  no  rigorous  conclusion 
must  be  drawn  from  what  happens  in  galvanic  phenomena,  to 
what  takes  place  in  muscular  action,  since  it  is  enough  that  a 
nerve  in  man  be  cut  or  compressed  by  a ligature,  to  take  from 


436 


ON  MOTION. 


the  muscles  to  which  it  is  sent,  the  faculty  of  moving.  I have, 
however,  observed  that  disorganizing,  by  a strong  contusion, 
the  nerve  which  forms  the  whole  or  merely  a part  of  the  animal 
arc,  interrupts,  or  at  least  greatly  impedes  the  galvanic  current. 

The  epidermis  obstructs  galvanic  action,  which  always  is 
faint  in  parts  so  covered.  When  it  is  moist,  thin,  and  delicate, 
the  interruption  is  not  complete,  and  hence  the  possibility  is 
inferred  of  making  on  oneself  the  following  experiments; — 

Lay  upon  the  tongue  a plate  of  silver,  and  a plate  of  zinc  be- 
neath; let  their  edges  touch,  and  you  will  feel  a sharp  taste  with 
a slight  quivering.  Apply  upon  the  eyes  two  pieces  of  different 
metals;  make  them  communicate  and  you  will  perceive  sparks. 
Put  a piece  of  silver  in  your  mouth,  and  a piece  of  tin  into  your 
anus,  or  copper  or  any  other  metal;  connect  them  with  an  iron 
wire;  the  long  hollow  muscle  which,  reaching  from  the  mouth 
to  the  anus,  forms  the  base  of  the  digestive  canal,  feels  a consi- 
derable shock;  this  has  been  carried  the  length  of  exciting  a 
gentle  purging,  accompanied  with  slight  colic.  Humboldt,  af- 
ter detaching  the  epidermis  from  the  nape  of  the  neck  and  the 
back,  by  two  blisters,  had  metals  applied  to  the  parts  laid  bare, 
and  felt  in  each  sharp  prickings,  accompanied  with  a sero-san- 
guineous  excretion,  at  the  moment  of  communication. 

You  may  construct  the  arch  of  excitation  with  three  kinds  of 
metal,  or  two,  or  even  one;  with  alloys,  amalgams  or  other  me- 
tallic and  mineral  combinations;  with  carbonaceous  substances,* 
See.,  and  it  is  observed,  that  metals  which  are,  in  general,  the 
most  powerful  exciters,  provoke  contractions  with  the  greater 
success  the  larger  surface  they  present.  The  metals  have  more 
or  less  power  of  excitation:  thus  it  is  found  that  zinc,  gold, 
silver,  and  tin,  hold  the  first  rank;  then  copper,  lead,  nickel, 
antimony,  &c.  without  any  apparent  relation  between  their  diffe- 
rent degrees  of  exciting  power  and  their  physical  properties,  as 
their  weight,  malleability,  &c. 

CLXX.  Galvanic  susceptibility  is  like  muscular  irritability: 
it  is  exhausted  by  too  long  exertion;  and  returns  when  the  parts 
are  left  for  a time  in  repose.  Dipping  the  nerves  and  muscles 

• I employed  successfully,  in  the  winter  of  the  year  VIII,  pieces  of  ice  both 
as  supports,  and  as  communicators. 


ON  MOTION. 


437 

in  alcohol  or  opiate  solutions,  weakens  and  even  will  extinguish 
this  susceptibility,  in  the  same  manner,  no  doubt,  as  in  the 
living  man,  the  immoderate  use  of  the  same  substances,  be- 
numbs and  paralyzes  the  muscular  action.  Immersion  in  oxy- 
genated muriatic  acid  restores  to  the  exhausted  parts  the  power 
of  being  affected  by  the  stimulus.  Humboldt  has  observed  that 
the  season  of  spring,  as  well  as  the  youth  of  the  frog,  was  fa- 
vourable to  the  production  of  the  phenomena,  and  that  the  fore- 
feet of  these  creatures  with  which  the  male  fixes  himself  on  the 
back  of  the  female,  by  pressing  her  sides,  are  more  excitable 
than  the  hind  feet;  whilst  in  the  other  sex,  it  is  the  hind  feet 
that  are  the  most  susceptible.  M.  Halle  ascertained,  by  experi- 
ments made  at  the  School  of  Medicine  in  Paris,  that  the  mus- 
cles of  animals  killed  by  repeated  shocks  of  an  electrical  bat- 
tery, receive  an  increase  of  galvanic  susceptibility;  that  this 
property  subsists,  without  , alteration,  in  animals  dead  of  as- 
phyxia or  killed  by  immersion  in  mercury,  pure  hydrogen  gas, 
carbonated  hydrogen,  oxygenated  muriatic  acid,  and  sulphu- 
reous acid  gases,  by  strangulation,  by  privation  of  air  in  an  ex- 
hausted receiver;  that  it  is  weakened  after  suffocation  by  drown- 
ing, by  sulphureted  hydrogen,  azote,  and  ammoniacal  gas,  and 
absolutely  destroyed  by  suffocation  in  the  vapour  of  charcoal. 
Spring  is  the  season  in  which  galvanic  experiments  succeed 
best;  an  excess  of  life  seems,  at  that  time,  to  animate  all  beings: 
it  is  accordingly  at  this  epoch,  that  the  greater  part  of  them  are 
employed  in  the  reproduction  of  their  kind. 

CLXXI.  Galvanic  susceptibility  disappears  in  the  muscles 
of  warm-blooded  animals,  as  the  vital  warmth  goes  off.  Some- 
times even,  when  their  life  has  ended  in  convulsions,  their  con- 
tractility is  gone,  though  there  be  still  warmth,  as  if  this  vital 
property  were  exhausted  by  the  convulsions  of  death.  In  the 
cold-blooded,  susceptibility  is  more  permanent:  long  after  se- 
paration from  the  body,  and  even  to  the  moment  when  putre- 
faction begins,  the  thighs  of  frogs  are  affected  by  galvanic  exci- 
tation; no  doubt,  because,  in  these  animals,  irritability  is  less  in- 
timately connected  with  respiration,  because  life  is  less  one,  is 
more  divided  among  different  organs  which  have  less  need  of 
action  on  each  other  to  produce  its  phenomena. 

Contractility  is  then,  as  I have  shown  in  another  work,  tao 


438 


ON  MOTION. 


fleeting  in  the  human  body,  to  enable  us  to  derive  from  galva- 
nic experiments  on  it,  after  death,  any  light  on  the  greater  or 
less  weakening  of  this  vital  property  in  diflFerent  diseases.  Those 
authors  who  have  maintained  that  galvanic  susceptibility  is 
sooner  extinct  on  the  bodies  of  those  that  die  of  scorbutic  af- 
fections, than  of  those  that  die  of  inflammatory  diseases,  have 
suggested  a probable  conjecture,  which  cannot,  however,  be 
established  on  experiment. 

Dr.  Pfaflf,  Professor  in  the  University  of  Kiel,  who,  next  to 
Humboldt,  is  of  all  the  scientific  men  of  Germany,  he  who  has 
attended  most  successfully  to  experiments  on  galvanism,  has 
had  the  goodness  to  communicate  to  me  the  following  facts: 

The  galvanic  chain  produces  sensible  actions,  that  js  to  say, 
contractions,  only  at  the  moment  in  which  it  is  completed,  by 
establishing  a communication  among  its  parts.  After  it  is  made, 
that  is,  during  the  time  that  the  communication  remains,  all  ap- 
pears tranquil;  yet  the  galvanic  action  is  not  suspended.  In  fagt, 
excitability  appears  singularly  increased  or  diminished  in  the 
muscles  that  have  been  left  long  in  the  galvanic  chain,  accord- 
ing to  the  variations  of  the  reciprocal  situation  of  the  associated 
metals.  If  the  silver  have  been  applied  to  the  nerves  and  the 
zinc  to  the  muscles,  the  irritability  of  these  is  increased  in  pro- 
portion to  the  time  they  have  remained  in  the  chain.  Bv  this 
means,  you  may  revivify,  in  some  sort,  frogs’  thighs,  which  will 
aftervvards  obey  an  influence  that  was  no  longer  sufficient  to  ex- 
cite them.  By  allotting  the  metals  differently,  applying  the  zinc 
to  the  nerves,  and  the  silver  to  the  muscles,  the  opposite  effect 
takes  place;  the  muscles  which  were  introduced  into  the  chain 
with  the  liveliest  irritability,  seem  entirely  paralyzed,  if  they 
have  remained  long  in  that  situation. 

This  difference  depends,  very  evidently,  on  the  direction  of 
the  galvanic  fluid,  determined  towards  the  nerves  or  towards 
the  muscles,  according  to  the  arrangement  of  the  metals.  It  is 
of  importance  to  be  known  , for  the  application  of  galvanism  to 
the  treatment  of  disease.  Where  the  object  is  to  revive  enfee- 
bled irritability,  it  is  better  to  employ  the  tranquil  and  perma- 
nent influence  of  the  closed  galvanic  chain,  by  distributing  the 
silver  and  zinc,  so  that  the  silver  shall  be  nearest  to  the  origin 
of  the  nerves,  and  the  zinc  upon  the  muscles  of  which  it  is  wish- 


ON  MOTION. 


439 


ed  to  re-excite  the  torpid  or  suspended  action,  than  to  employ 
that  sudden  influence,  which,  in  an  instant,  excites  and  is  gone. 
Professor  PfalF  told  me,  he  had  treated  successfully  a hemi- 
phlegia,  by  placing  silver  within  the  mouth,  and  a plate  of  zinc 
on  the  paralyzed  arm;  at  the  end  of  24  hours  of  uninterrupted 
communication,  the  limb  could  already  exert  some  slight  mo- 
tions. To  diminish,  on  the  other  hand,  the  irritable  energy  in 
many  spasmodic  affections,  you  must  invert  the  applications  of 
the  metals,  place  the  zinc  as  near  as  possible  to  the  central  ex- 
tremity of  the  nerves,  and  the  silver  on  their  superficial  termi- 
nations. 

CLXXII.  Apparatus  of  Volta^  or  galvanic  pile.  Curious  to 
ascertain  the  relation  apprehended  by  several  natural  philoso- 
phers, between  electricity  and  galvanism,  M.  Volta  invented 
the  following  apparatus,  which  is  described,  as  well  as  the  ef- 
fects it  produces,  in  a memoir  presented  by  him  to  the  Royal 
Society  of  London.  These  effects  show  the  most  striking  ana- 
log)' between  these  two  orders  of  phenomena,  as  will  be  seen  by 
a succinct  view  of  them.  Raise  a pile,  by  laying  successively,  one 
above  another,  a plate  of  zinc,  a piece  of  moistened  paste-board, 
a plate  of  silver;  then  a second  plate  of  zinc,  Stc.  till  the  pile  is 
several  feet  high;  for,  the  effects  are  stronger  the  higher  it  is; 
then,  touch,  at  once,  the  two  extremities  of  the  pile  with  the 
same  iron  wire;  at  the  instant  of  contact,  a spark  is  seen  at  the 
extremities  of  the  pile,  and  often,  at  the  same  time,  luminous 
points,  at  different  heights,  in  places  where  the  zinc  and  silver 
touch.  Tried  by  the  electrometer  of  M.  Coulomb,  the  extremity 
of  the  pile,  which  answers  to  the  zinc,  appears  positively  elec- 
trified; that  which  is  formed  by  the  silver,  gives,  on  the  con- 
trary, indications  of  negative  electricity. 

If  after  wetting  both  hands,  by  dipping  them  in  water,  or  still 
better,  in  a saline  solution,  you  touch  the  two  extremities  of  the 
pile,  you  feel,  in  the  joints  of  the  fingers  and  elbow,  a shock  fol- 
lowed by  an  unpleasant  pricking. 

This  effect  may  be  felt  by  several  persons  holding  hands,  as 
in  the  Leyden  experiment;  it  is  the  more  sensible,  the  composi- 
tion of  the  chain  being  in  other  respects  the  same,  as  the  chain 
consists  of  fewer  people,  and  as  they  are  better  insulated. 

Notwithstanding  this  great  resemblance  of  the  effects  of  gal- 


ON  MOTION. 


440 

vanism  to  those  of  electricity,  it  differs  from  it  essentially  in 
this,  that  the  voltaic  pile  is  constantly  electrifying  itself  sponta- 
neously; that  its  effects  seem  increased,  the  more  they  are  ex- 
cited, and  are  speedily  renewed  in  greater  strength;  whilst  the 
Leyden  phial,  once  discharged,  requires  to  be  electrified  anew. 
This  loses,  moreover,  by  damp,  its  electrical  properties,  whilst 
those  of  the  pile  remain  the  same,  though  water  is  running  on 
all  sides,  and  are  quenched  only  by  entire  immersion  in  that 
fluid. 

If  you  introduce  into  a tube  filled  with  water,  and  hermeti- 
cally closed  with  two  corks,  the  extremities  of  two  wires  of  the 
same  metal,  which  at  the  other  extremity  are  in  contact,  one 
with  the  summit,  and  one  with  the  base  of  the  galvanic  pile,  these 
two  ends,  when  brought  within  the  distance  of  a few  lines,  un- 
dergo manifest  changes,  at  the  moment  of  touching  the  extre- 
mities of  the  pile.  The  wire  in  contact  with  the  extremity  which 
answers  to  the  zinc,  becomes  covered  with  bubbles  of  hydrogen 
gas;  that  which  touches  the  extremity  formed  by  the  silver,  be- 
comes oxydized.  If  the  ends  of  the  wire  dipping  into  the  water, 
are  brought  into  contact,  all  effect  ceases:  there  is  no  disen- 
gaging of  bubbles  on  one  side,  no  oxydizement  on  the  other.  The 
plates  of  zinc  and  silver  become  alike  oxydized  in  the  pile,  but 
only  on  the  surfaces  which  touch  the  moistened  paste-board, 
and  very  little,  or  not  at  all,  on  the  opposite  surfaces,  &c. 

Facts  so  singular  could  not  but  awaken  the  attention  of  all 
natural  philosophers.  Accordingly,  there  was  great  eagerness, 
every  where,  to  repeat  and  verify  these  first  experiments,  to 
vary  and  to  extend  them,  and  to  rectify  the  errors  into  which 
their  authors  might  have  fallen.  Lastly,  it  has  been  attempted 
to  explain  the  manner  in  which  the  apparatus  acts  in  the  pro- 
duction of  hydrogen  gas  and  in  oxydizement. 

M.  Fourcroy  ascribes  this  phenomenon  to  the  decomposition 
of  water  by  the  galv’anic  fluid,  which  abandons  the  oxygen  to 
the  wire  that  touches  the  positive  extremity  of  the  apparatus, 
then  conducts  the  other  gas,  in  an  invisible  manner,  to  the  ex- 
tremity of  the  other  wire,  where  it  allows  it  to  escape:  and  this 
opinion,  supported  by  many  experiments  detailed  in  a IMemoir 
presented  to  the  National  Institute,  is  the  most  probable  of  all 
that  have  hitherto  been  suggested. 


ON  MOTION. 


The  galvanic  pile  has  been  employed,  with  effect,  to  produce 
with  more  energy,  muscular  contraction.  If  you  place  in  the 
mouth  of  an  animal,  fresh  killed,  a conductor  attached  to  one 
of  the  poles  or  extremities  of  the  pile,  and  insert  into  the  rec- 
tum the  conductor  connected  with  the  other  extremity,  you 
observe  contractions  so  strong,  that  the  whole  body  of  the  ani= 
mal  quivers  and  is  agitated,  the  eyes  roll  in  their  sockets,  the 
jaws  strike  against  each  other,  and  the  tongue  is  thrust  out. 
The  same  effects  take  place  after  decapitation  of  the  animal. 
These  experiments  have  been  repeated  on  the  bodies  of  persons 
executed  by  the  guillotine:  by  applying  to  the  neck,  the  head 
that  had  been  separated  from  it,  and  applying  to  both,  conduc- 
tors connected  with  the  pile,  effects  have  been  produced,  which 
seemed  at  first  miraculous.  There  are  few  muscles  that  retain, 
longer  than  the  diaphragm,  their  sensibility  to  the  galvanic  ac- 
tion; in  the  heart  and  the  intestines  it  is  the  same.  I know  not 
why  the  internal  muscles  have  been  held  by  many  authors  to  be 
insensible  to  this  kind  of  excitation.  I have  seen  them  con- 
stantlv  obey  it,  and  many  experiments  made  publicly  in  my 
lectures,  have  always  afforded  me  this  result. 

CLXXIII.  In  the  first  edition  of  this  work  the  article  gal- 
vanism ended  here.  Since  its  publication,  there  has  been  an 
accession  of  new  facts  to  those  already  known.  Volta  came  to 
Paris:  he  gave  an  exposition  of  his  doctrine,  in  several  me- 
moirs read  before  the  National  Institute  of  France,  and  he 
repeated  before  a committee,  the  principal  experiments  on 
which  it  is  founded.  They  have  appeared  so  conclusive,  that 
the  theory  of  this  illustrious  philosopher  has  been  unanimously 
adopted;  and  at  this  day,  all  men  of  science  admit  the  entire 
identity  of  the  phenomena  of  galvanism,  and  those  of  electri- 
city. Certain  bodies,  therefore,  in  nature,  and  especially  metals, 
possess  the  property  of  electrifying  themselves,  that  is  to  say, 
of  producing  the  greater  part  of  the  phenomena  which  denote 
the  accumulation  of  electricity  in  a body,  such  as  shocks,  sparks, 
irritations,  &c.  merely  by  contact. 

It  may  be  thought  that  galvanism,  being  only  a new  form  of 
electrical  action,  ought  to  be  confined  to  ‘books  of  natural  phi- 
losophy: and  in  fact,  in  the  present  state  of  things,  it  belongs 
rather  to  the  physico-chemical  sciences,  than  to  those  of  the 

3 K 


442 


ON  MOTION. 


animal  economy.  However,  the  galvano-electric  irritation  pro- 
duces on  our  organs,  effects  more  decided  than  the  ordinary 
effects  of  electricity.  It  seems  to  have  more  intimate  relations 
with  them:  accordingly,  it  has  been  endeavoured  to  bring  it 
into  use  in  the  treatment  of  disease.  The  experiments  made  by 
MM.  Halle  and  Thillaye,  prove  that  the  effects  of  the  pile 
penetrate,  and  affect  the  nervous  and  muscular  organs,  more 
deeply  than  the  common  electrical  apparatus;  that  they  provoke 
lively  contractions,  strong  sensations  of  pricking  and  burning, 
in  parts  which  disease  renders  insensible  to  electrical  sparks, 
or  even  shocks.  A man  whose  muscles  of  the  left  side  of  his 
face  were  all  paralysed,  found  no  effect  from  the  electrical  shock. 
He  was  exposed  to  the  action  of  a pile  of  fifty  plates,  by  com- 
munications, through  chains  and  metallic  exciters,  of  the  two  ex- 
tremities of  the  pile,  with  different  points  of  the  cheek  affected. 
At  the  moment  of  contact,  all  the  muscles  of  the  face  became 
convulsed,  with  heat,  pain.  See.  These  endeavours  repeated, 
during  more  than  six  months,  have,  by  degrees,  brought  back 
the  parts  to  their  natural  state. 

Dr.  Alibert  has  applied  galvanism  with  still  more  decided 
success,  to  a priest  attacked  with  hemiplegia.  This  patient, 
who  lay  in  the  wards  of  the  Hospital  of  St.  Lewis,  has  reco- 
vered the  use  of  the  palsied  side,  sufficiently  to  walk,  almost 
without  assistance,  and  to  use  his  right  arm  as  he  wants  it. 
The  treatment  has  gone  on  for  several  months:  the  pile  em- 
ployed consisted  of  fifty  plates  of  zinc  and  copper.  I am  trying 
the  same  apparatus  upon  a Swedish  officer,  for  incomplete  deaf- 
ness, which  has  hitherto  resisted  all  known  applications,  ad- 
ministered in  different  parts  of  Germany.  Strong  electrical 
shocks,  recommended  by  Hufeland,  had  dispelled,  in  great 
measure,  the  hardness  of  hearing:  but  this  amendment  was  only 
temporary:  it  ceased  with  the  application  of  the  remedy.  The 
first  trial  of  galvanism  was  attempted  with  the  same  effect.  The 
extremity  of  a conductor  being  placed  in  the  exterior  auditory 
duct  of  the  right  side  (moistened  with  a solution  of  muriate  of 
ammonia,  as  well  as  the  pieces  of  cloth  which  made  part  of  the 
pile)  the  left  hand,  dipped  in  the  same  liquid,  touched  a con- 
ductor placed  at  the  copper  pole:  immediately  an  irritation,  fol- 
lowed by  painful  prickings,  was  felt  in  the  ear,  the  outer  part  of 


ON  MOTION. 


443 


which  became  very  red.  The  brain  partook  in  the  excitement;  • 
the  eyes  flashed,  and  the  effect  was  such,  that  after  remaining  a 
few  minutes  in  the  closed  galvanic  circle,  the  patient  was  taken 
with  a sort  of  inebriation.  I propose  to  direct,  as  has  been  done 
at  Berlin,  a more  immediate  irritation  on  the  right  ear,  which 
is  the  deafest,  by  introducing  behind  the  velum  palati,  on  the 
guttural  orifice  of  the  Eustachian  tube,  the  button  which  Is  at 
the  end  of  the  conductor  of  the  zinc  pole;  or  else  to  make  this 
extremity  correspond  with  a denuded  surface,  by  a blister  be- 
hind the  diseased  ear. 

To  use  galvanism,  in  paralysis  of  the  bladder,  it  would  be 
necessary  to  place  the  conductor  of  the  zinc  pole  in  the  rectum, 
that  of  the  other  pole  answering  to  a blister  applied  above  the 
pubis,  or  else  to  the  upper  part  of  the  thigh.  In  women,  the 
vagina  would  be  preferable  to  the  rectum;  the  soft  parts  which 
perform  the  part  of  moist  conductors  fulfilling  that  office  the 
better,  the  thinner  they  are.  Galvanism  is  therefore  an  ener- 
getic stimulant  of  the  vital  powers;  it  may  be  employed,  with 
great  advantage,  In  all  palsy  both  of  sensation  and  of  motion. 
It  acts  as  a stimulant,  reddening  the  skin  where  It  is  applied, 
by  determining  thither  the  flow  of  blood,  with  heat.  Monro 
could  make  his  nose  bleed  at  pleasure,  by  applying  it  to  the 
pituitary  membrane.  I have  made  various  experiments  having 
in  view  to  establish  the  efficacy  of  galvanism,  in  white  swelling 
of  the  joints,  and  in  ulcers  which  require  excitement;  such  as 
those  which  are  attended  with  a scorbutic  affection,  &c.  In  all 
these  cases,  it  acts  as  a resolvent  and  as  a tonic.  I shall  com- 
municate, in  my  Surgical  Nosography,  the  results  of  these 
attempts.  Cases  of  asphyxia  are  those  in  which  the  greatest 
good  may  be  hoped  for  from  galvanism,  provided  the  applica- 
tion be  made  before  all  the  vital  heat  be  extinct. 

Those  who  would  wish  fuller  details  on  galvanism,  and  on 
its  possible  application  to  the  treatment  of  disease,  will  do  well 
to  consult  the  complete  History  of  Galvanism,  by  Professor 
Sue,  theeulogium  of  Galvani,  by  Dr.  Alibert,  in  the  beginning 
of  the  fourth  volume  of  the  Memoirs  of  the  Medical  Society  of 
Emulation,  and  the  works  of  Dr.  Aldini,  nephew  to  the  cele- 
brated author  of  the  discovery. 


444 


ON  MOTION. 


CLXXIV.  General  view  of  the  osseous  system,  Man,  as 
well  as  the  other  red-blooded  animals  (the  mammiferse,  birds, 
reptiles,  and  fishes)  has  an  internal  skeleton,  formed  of  a great 
number  of  bones  articulated  together,  and  set  in  motion  by  the 
muscles  with  which  they  are  covered.  The  white-blooded  ani- 
mals have  no  internal  skeleton,  and  are  enveloped  in  hard, 
scaly,  or  stony  parts,  forming  what  is  called  their  outer  skeleton. 
Some  animals  are  entirely  destitute  of  hard  parts;  this  is  the 
case  with  the  zoophytes,  some  worms  and  insects.  The  inter- 
nal structure  of  bones  is  composed  of  nearly  the  same  materials 
in  all  animals:  viz.  gelatine  and  salts  containing  a calcareous 
basis.  The  external  skeleton  of  white-blooded  animals  bears  a 
much  greater  resemblance  to  the  epidermis  than  to  the  osseous 
system  of  the  red  blooded  animals.  Like  the  epidermis,  it  un- 
dergoes changes  of  decomposition  and  renovation.  Thus,  the 
lobster  parts  with  its  shell,  every  year,  when  the  body  of  this 
crustaceous  animal  increases  in  size,  and  it  is  replaced  by  a new 
envelope,  which  is  at  first  very  soft,  and  which  gradually  ac- 
quires the  same  consistence  as  the  former.  Lastly,  the  skeleton 
of  birds  differs  from  that  of  all  other  animals,  in  having  its 
principal  bones  pierced  by  openings  communicating  with  the 
lungs,  and  always  filled  with  an  air  rarefied  by  the  vital  heat, 
which  greatly  assists  in  giving  to  them  that  specific  lightness  so 
essential  to  their  peculiar  mode  of  existence. 

The  osseous  system  serves  as  a foundation  to  the  animal 
machine,  yields  a firm  support  to  all  its  parts,  determines  the 
size  of  the  body,  its  proportion,  its  form  and  attitude.  Without 
the  bones,  the  body  would  have  no  permanent  form,  and  could 
not  easily  move  from  one  place  to  another.  When,  from  the 
loss  of  the  calcareous  earth  to  which  they'  owe  their  hardness, 
these  organs  become  soft,  the  limbs  deformed,  standing,  and 
the  different  motions  of  progression,  become  after  a time  im- 
possilile.  Such  are  the  effects  of  rachitis,  a disease  of  which 
the  nature  is  well  understood,  though  we  are  not  the  better  in- 
formed with  r.  gard  to  the  manner  in  which  its  causes  operate, 
or  the  medicines  which  it  requires. 

The  vertebral  column  forms  the  truly  essential  and  funda- 
mental part  of  the  skeleton;  it  may  be  considered  as  the  base 
of  the  osseous  edifice,  as  the  point  in  which  all  their  efforts  ter- 


ON  MOTION. 


445 

miiiatei  as  the  centre  on  which  all  the  bones  rest  in  their  va- 
rious motions,  since  every  eflPort  or  shock,  in  any  way  conside- 
rable, is  felt  there.  Moreover,  it  contains  in  the  canal  with 
which  it  is  perforated,  the  cerebral  prolongation,  which  furnishes 
most  of  the  nerves  in  the  body. 

In  ordev  that  it  may  support  all  the  different  parts,  and,  at  the 
same  time,  protect  the  delicate  organ  which  it  contains,*  and 
adapt  itself  to  the  various  attitudes  required  by  the  wants  of  life, 
it  was  necessary  that  the  vertebral  column  should  possess,  be- 
sides great  solidity,  a sufficient  degree  of  mobility;  it  possesses 
both  these  advantages,  and  owes  the  former  to  the  breadth  of 
the  surfaces  by  which  its  bones  are  articulated  together,  to  the 
size,  the  length,  the  direction  and  the  strength  of  their  pro- 
cesses, and  to  the  great  number  of  muscles  and  ligaments  con- 
nected with  it:  it  Owes  its  freedom  of  motion  to  the  great  num- 
ber of  bones  of  which  it  is  formed.  Each  single  vertebra  has 
but  a slight  degree  of  motion,  but  as  they  all  have  the  power  of 
moving  at  once,  the  sum  of  their  individual  motion  added  to- 
gether, gives  as  the  result  a general  motion  which  is  considera- 
ble, and  which  is  estimated  by  multiplying  the  single  motion  by 
the  number  of  vertebrae. 

The  centre  of  the  motions,  by  which  the  spine  is  extended  or 
bends  forward  or  backward,  is  not  situated  in  the  articulation 
of  the  oblique  processes,  as  is  maintained  by  Winslow,  in  the 
Memoirs  of  the  Academy  of  Sciences  for  the  year  1730,  nor  in 
the  intervertebral  substance.  The  extension  and  flexion  of  the 
vertebrae  are  not  performed  on  two  centres  of  motion,  the  one 
in  the  intervertebral  substance,  the  other'  in  the  articulations  of 
the  articulating  processes,  as  was  imagined  by  Cheselden  and 
Barthez,  but  on  an  axis  crossing  the  bone  between  its  body  and 
its  great  aperture.  The  anterior  part  of  the  bone  and  its  spinous 

* The  peculiaMnanner  in  which  the  vei’tebrje  grow,  is  itself  accommodated 
to  the  delicacy  of  the  spinal  marrow;  consisting,  for  a considerable  length  of 
time,  of  several  pieces  divided  by  cartilages,  the  circumference  of  the  opening 
in  these  bones,  becomes  enlarged,  with  the  enlargement  of  the  spinal  marrow, 
as  we  grow  older.  The  circumference  of  the  foramen  of  the  occipital  bone 
and  that  of  the  first  vertebra,  which  correspond  to  the  thickest  part  of  the 
spinal  marrow,  is,  on  that  account,  formed  of  four  distinct  pieces  separated  by 
c artilages  in  the  first  of  these  bones,  and  of  five  pieces  in  the  other. 


446 


ON  MOTION. 


process  perform,  around  this  imaginary  axis,  motions  forming 
part  of  a circle,  and  which  though  limited  are  not  the  less 
marked;  and  in  these  motions  the  articulating  surfaces  separated 
by  the  intervertebral  substance  are  brought  into  close  contact, 
and  this  substance  is  compressed,  while  the  oblique  processes 
move  on  one  another,  and  tend  to  part  from  one  another;  this  is 
what  happens  in  bending  the  trunk,  while,  in  straightening  it, 
the  anterior  surfaces  are  removed  from  each  other,  the  poste- 
rior surfaces  approach,  come  closer  and  closer  together,  and 
finally  touch  throughout  the  whole  of  their  extent,  when  the 
extension  of  the  trunk  is  carried  as  far  as  the  spinous  processes 
will  allow. 

The  use  of  the  ridge  of  projections  which  arise  from  the  pos- 
terior part  of  the  vertebrae,  is  to  limit  the  bending  of  the  trunk 
backwards,  and  to  enable  the  muscles  which  straighten  it,  to  act 
with  a more  powerful  lever.  When,  from  the  habit  of  an  habi- 
tually erect  posture,  these  processes  have  been  prevented  from 
growing  in  their  natural  direction,  the  trunk  may  be  bent  back- 
ward to  such  a degree,  that  the  body  forms,  in  that  direction,  an 
arc  of  a circle.  It  is  thus  that  they  train,  from  the  earliest  in- 
fancy, the  tumblers  who  astonish  us  by  the  prodigious  supple- 
ness of  their  loins,  in  bending  backward  so  as  to  change  the  na- 
tural direction  of  their  spinal  processes. 

It  was  of  consequence,  that  the  motions  of  the  vertebral  co- 
lumn should  take  place,  at  once,  in  a great  number  of  articula- 
tions, as  the  curvatures  are  thus  less  sharp,  and  thus  the  organi- 
zation of  the  spinal  marrow,  which  is  very  delicate,  is  not  injur- 
ed. The  fibro-cartilaginous  substances  which  connect  together 
the  bodies  of  the  vertebra,  between  which  they  lie,  possess  a re- 
markable degree  of  elasticity,  like  all  bodies  of  the  same  kind, 
and  support,  in  a favourable  manner,  the  weight  of  the  body. 
When  the  pressure  which  they  experience  is  long  continued, 
they  somewhat  yield,  and  diminish  in  thickness;  and  this  effect 
taking  place,  at  the  same  time,  in  all  the  intervertebral  sub- 
stances, our  stature  is  sensibly  lowered.  The  body  is,  on  that 
aecount,  always  shorter  in  the  evening  than  in  the  morning,  and 
this  difference  may  be  considerable,  as  is  mentioned  by  Buffon 
to  have  been  the  case  in  several  instances.  The  son  of  one  of 
his  most  zealous  coadjutors  (M.  Gueneau  de  Montbeillard,  to 


ON  MOTION*. 


447 

whom  is  due  the  greatest  part  of  the  natural  history  of  birds), 
a young  man  of  tall  stature,  five  feet  nine  inches  when  he  had 
reached  his  complete  growth,  once  lost  an  inch  and  an  half, 
after  spending  a whole  night  at  a ball.  This  difference  in  the 
stature  depends,  likewise,  on  the  condensation  of  the  cellular 
adipose  tissue  at  the  heel,  which  forms,  along  the  whole  of  the 
sole  of  the  foot,  a pretty  thick  layer. 

The  thigh  bone  is  longer  in  man  than  in  quadrupeds,  and 
this  relative  length  of  the  thigh  gives  him  exclusively  the 
power  of  resting  his  body  by  sitting. 

The  tibia  is  the  only  one  of  the  bones  of  the  leg  which  affords 
a support  to  the  body.  The  fibula,  situated  at  its  outer  part,  too 
thin  and  slender  to  support  the  weight  of  the  body,  is  of  use 
merely  with  regard  to  the  articulation  of  the  foot,  on  the  out- 
side of  which  it  lies.  It  supports  the  foot,  and  prevents  its  start- 
ing outward  by  too  powerful  an  abduction.  The  foot,  in  this 
motion,  is  forced  against  the  fibula  which  is  bent  outwardly,  the 
more  so  when  the  person  is  advanced  in  years,  and  has,  there- 
fore, called  into  frequent  action  this  force  of  resistance.  Ani- 
mals that  climb,  as  the  squirrels,  whose  feet  are  in  a continual 
state  of  abduction,  have  a very  large  and  strongly  curved 
fibula.* 

The  number  of  the  parts  which  form  the  feet,  besides  giving 
to  these  parts  a greater  solidity,  is  further  useful  in  preventing 
the  foot  from  being  too  violently  shaken  by  striking  the  ground, 
in  our  various  motions  of  progression.  In  leaping  from  a height, 
we  endeavour  to  fall  on  our  toes,  that  the  force  of  the  fall  may 
be  broken,  by  being  communicated  to  the  numerous  articula- 
tions of  the  tarsus  and  metatarsus,  and  may  not  affect  the  trunk 

* This  curvature  is  well  marked  in  the  chefs-d’oeuvre  of  antique  sculpture, 
and  gives  to  the  lo-wer  part  of  the  leg,  in  our  most  beautiful  statues,  a thick- 
ness which  does  not  at  all  agree  with  our  present  notions  of  elegance  of  form. 
This  seems  to  me  to  prove,  that  the  beautiful  is  not  invariable,  as  has  been  as- 
serted by  many  philosophers;  and  that  ideal  perfection  is  not  precisely  the  same 
in  all  ages,  in  nations  equally  civilized.  The  truth  of  this  observation  may  be 
proved  by  the  Apollo  Belvedere;  his  knees  are  rather  large  and  close  together, 
and  this  form  is  the  most  beautiful  representation  of  nature,  which  gives  to 
the  femur  an  obliquity  inwards,  the  knees  not  being  perfectly  straight,  and 
without  any  disproportion  between  the  calf  and  the  thin  part  of  the  leg. 


448 


ON  MOTION. 


and  head  with  a painful  and  even  dangerous  concussion.  It  is 
well  known,  that  when,  in  falls,  the  whole  sole  of  the  foot 
strikes  against  the  ground,  fracture  of  the  neck,  of  the  thigh 
bones,  and  concussion  of  the  brain  and  other  organs,  is  not  an 
unlikelv  consequence. 

CLXXV.  Structure  of  the  hones.  Whatever  difference  there 
may,  at  first  sight,  seem  to  exist,  between  a bone  and  another 
organ,  their  composition  is  the  same.  Its  structure  consists  of 
parts  that  are  perfectly  similar,  with  the  exception  of  the  saline 
inorganic  matter  which  is  deposited  in  the  cells  of  its  tissue, 
which  gives  it  hardness  and  that  solidity  which  constitutes  the 
most  striking  difference  that  distinguishes  it  from  the  soft  parts. 
This  earthy  substance  may  be  separated  by  immersing  the  bone 
in  nitric  acid  diluted  in  a sufficient  quantity  of  water.  It  is  then 
found,  that  it  is  a phosphate  of  lime  which  is  decomposed,  by 
yielding  to  the  nitric  acid  its  calcareous  base.  The  bone,  thus 
deprived  of  die  principle  to  which  it  owes  its  consistence,  be- 
comes soft,  flexible,  and  resembles  a cartilage,  which  is  re- 
solvable, by  long  maceration,  into  a cellular  tissue,  similar  to 
that  of  the  other  parts.  This  tissue  contains  a pretty  considera- 
ble number  of  ^arteries,  veins,  and  lymphatics.  The  bones  are, 
therefore,  mere  cellular  parenchymas,  whose  areolae  contain  a 
crystallized  saline  substance,  which  they  separate  from  the 
blood,  and  with  which  they  become  incrusted,  by  a power  inhe- 
rent in  their  tissue  and  peculiar  to  it.  The  same  result  may  be 
obtained  by  inverting  the  analysis.  If  a bone  is  exposed  to  boil- 
ing heat,  for  a few  hours,  in  Papin’s  digester,  all  its  organized 
parts  become  dissolved,  melt,  and  furnish  a quantity  of  gelatine, 
after  which  there  remains  only  an  inorganic  saline  concretion; 
which  may,  likewise,  be  obtained  in  a separate  state  by  calcin- 
ing the  osseous  part.  The  different  proportions  of  the  saline  to 
the  organized  part,  vary  considerably  at  different  periods  of  life; 
the  bones  of  the  embryo  are,  at  first,  quite  gelatinous.  At  the 
period  of  birth,  and  during  the  first  years  of  life,  the  organic 
part  of  the  bone  is  in  greater  proportion;  the  bones  are  less  apt 
to  break,  more  flexible,  possessed  of  more  vitality,  and,  when 
fractured,  are  more  speedily'  and  more  easily  consolidated.  In 
youth,  the  two  constituent  parts  are  nearly  in  equal  quantities; 


ON  MOTION. 


449 

m adults,  the  calcareous  earth*  alone  forms  two  thirds  of  the 
osseous  substance.  At  last,  gradually  increasing  in  quantity,  it 
displaces,  in  old  people,  the  part  that  is  organized;  hence  their 
bones  are  weaker,  more  liable  to  fracture,  and  unite  less  readily. 
One  may  therefore  say,  that  the  quantity  of  phosphate  of  lime 
deposited  in  the  bones,  is  in  the  direct  ratio  of  the  age;  and  that, 
on  the  contrary,  the  energy  of  the  vital  faculties  of  these  organs, 
their  flexibility,  their  elasticity,  their  aptitude  to  become  conso- 
lidated, when  their  continuity  is  destroyed  by  accidents,  are  in 
an  inverse  ratio. 

Anatomists  distinguish  in  bones  three  substances,  which  they 
term  compact,  spungy,  and  reticular.  The  first,  which  is  the 
hardest,  collected  in  the  centre  of  the  long  bones,  where  the 
greatest  stress  of  the  efforts  applied  to  their  extremities  rests, 
gives  to  the  bone  the  strength  which  it  required.  Its  formation 
has  been  explained,  in  various  ways;  some  have  maintained  that 
it  owed  its  hardness  to  the  pressure  applied  to  its  middle  part 
by  the  two  extremities  of  the  bone;  in  the  same  manner  as  the 
stalk  and  the  roots  press  against  the  collet\  of  a plant.  Haller 
thinks  it  is  caused  by  the  pulsations  of  the  nutritious  arteries 
which  penetrate  into  the  long  bones,  at  their  middle  part;  why 
then  is  their  structure  different  at  their  extremities,  where  they 
receive  arteries  equally  large  and  more  numerous?  In  the  pro- 
cess of  ossification,  this  substance  appears  first  in  the  centre  of 
the  long  bones;  and  this  confirms  the  assertion  of  Kerkringius, 
who  says,  that  our  long  bones  begin  to  ossify  in  those  points 
where  they  have  to  resist  the  greatest  pressure. 

The  spungy  substance  is  found  within  the  short  bones,  and 
at  the  extremities  of  the  long  ones,  where  its  accumulation  is 
attended  with  two  advantages,  that  of  giving  to  the  bone,  with- 
out increasing  its  weight,  a considerable  size,  by  which  it  may 
be  articulated  with  the  neighbouring  bones,  by  wide  surfaces, 

* By  chemical  analysis  of  the  bones,  there  have  been  discovered  several 
other  saline  substances  mixed  with  the  phosphate  of  lime;  but  as  tliis  salt 
alone  constitutes  the  greatest  part  of  the  substance  which  gives  to  the  bones 
their  hardness,  I thought  that  it  would  be  useless  to  enter  into  minute  details, 
in  a work  of  this  kind,  by  giving  an  account  of  the  more  reoent  chemidal 
analyses. 

f The  part  where  the  stem  joins  the  root.— T. 

3 L 


450 


ON  MOTION. 


SO  as  to  give  firmness  to  their  connexions;  this  conformation  Is 
attended  with  another  advantage,  that  of  avoiding  the  paral- 
lelism of  the  tendons  which  pass  over  the  joints,  in  order  to 
enlarge  the  angle  of  their  insertion  in  the  bones,  and  to  give 
more  efficacy  to  muscular  action.  The  mechanical  hypotheses 
proposed  by  Haller  and  Duhamel,  to  explain  the  formation  of 
this  spungy  substance,  are  very  unsatisfactory,  especially  if  it 
be  considered,  that  in  the  gelatinous  bones  of  the  embryo,  the 
place  that  is  to  be  occupied  by  the  spungy  substance,  viz.  the  ex- 
tremities of  the  long  bones,  of  which  the  rudiments  begin  to  ap- 
pear, are  larger  than  any  other  part.  All  the  cells  of  this  spungy 
substance  communicate  with  one  another,  they  are  lined  by  a 
very  fine  membrane,  and  contain  the  medullary  fluid.  The 
laminae  which  cross  each  other,  in  various  directions,  and  which 
form  the  parietes  of  the  cells,  become  fewer  in  number  and 
thinner;  the  spungy  tissue  expands  in  approaching  the  middle 
part  of  the  bones,  and  forms  (within  the  medullary  canal,  of  the 
compact  substance)  a reticular  tissue,  the  use  of  which  is  to 
support  the  membranous  tube  containing  the  marrow. 

These  three  substances,  notwithstanding  their  unequal  den- 
sity, are,  in  reality,  but  one  and  the  same  substance  differently 
modified.  The  reticular  and  spungy  differ  from  the  compact, 
in  containing  less  phosphate  of  lime,  and  in  having  a rarer  and 
more  expanded  tissue.  In  other  respects,  those  changes  in  the 
osseous  tissue  which  constitute  the  laminated  exostoses,  the 
conversion  of  the  bones,  by  acids,  into  a flexible  cartilage, 
which,  by  maceration,  may  be  reduced  into  cellular  tissue, 
prove  that  these  three  substances  are  truly  identical,  and  differ 
from  each  other,  only  by  the  degrees  of  closeness  of  their  tex- 
ture and  the  quantity  of  calcareous  phosphate  deposited  in  the 
meshes  of  their  tissue. 

The  compact  substance  appears  to  consist  of  concentric  lami- 
nse  strongly  united  together,  and  to  be  formed  of  fibres,  arranged 
longitudinally,  and  in  juxta  position.  In  proof  of  this  arrange- 
ment, it  is  usual  to  mention  the  exfoliation  of  bones  exposed  to 
the  air;  but  these  laminae  detached  from  an  exfoliating  bone, 
merely  prove  that  the  action  of  the  disease,  the  air,  heat,  or 
any  other  agent,  by  applying  itself  successively  to  the  different 
layers  of  bone,  produces  between  them  a separation  which  did 


ON  MOTION. 


451 


not  exist  in  health,  and  determines  their  falling  olF  in  succes- 
sion. Certain  parts,  in  which  this  lamellated  structure  does  not 
exist,  may,  in  like  manner,  undergo  the  same  kind  of  decompo- 
sition. Thus,  Lassone  saw  a piece  of  human  skin  that  had  been 
preserved,  for  a considerable  length  of  time,  in  a vault,  separate 
into  layers  of  extreme  minuteness. 

The  vital  principle  which  exists,  in  a smaller  degree,  in  the 
bones  than  in  other  parts,  seems  to  animate,  to  a certain  degree, 
their  different  substances.  Proportioned  to  the  number  of  ves- 
sels which  are  distributed  to  it,  life  is  more  active  in  the  spungy 
tissue;  hence,  in  fracture  of  this  part,  fleshy  granulations  and 
callus  form  more  quickly.  Caries,  likewise,  advances  more 
rapidly,  and  it  is  more  difficult  to  interrupt  its  progress. 

CLXXVI.  Of  the  uses  of  the  periosteum  and  of  the  medullary 
juices.  Whatever  be  the  situation,  the  size,  the  shape,  and  the 
composition  of  bones,  they  are  all  enveloped  by  the  periosteum, 
a whitish,  fibrous,  dense  and  compact  membrane,  to  which  are 
distributed  the  vessels  which  penetrate  into  their  substance. 
The  periosteum  is  a membrane  perfectly  distinct  from  the 
other  soft  parts,  and  from  the  bone  itself,  to  which  it  adheres 
by  means  of  vessels  and  of  cellular  tissue  which  pass  from  the 
one  to  the  other,  the  more  closely,  as  we  are  more  advanced  in 
years.  The  cellular  and  vascular  fibres  which  penetrate  into 
the  substance  of  the  bone,  establish  a very  close  sympathetic 
connection  between  its  periosteum  and  the  very  delicate  mem- 
brane that  lines  its  internal  cavity,  which  secretes  the  marrow, 
and  is  called  the  internal  periosteum.  On  destroying  the  inter- 
nal medullary  membrane,  by  introducing  a stylet  within  the 
cavity  of  the  bone,  its  external  layers  swell,  are  detached  from 
the  inner  ones,  and  form,  as  it  were,  a new  bone  around  the 
sequestra.  The  new  bone  is  not  formed  by  the  ossification  of 
the  periosteum,  as  was  maintained  by  Troja.  This  membrane 
has  no  more  to  do  with  the  formation  of  the  new  bone,  in  ne- 
crosis, than  with  that  of  the  callus  in  fracture.  The  periosteum, 
covering  a bone  affected  with  necrosis,  does  not  become  thicker, 
and  does  not  acquire  more  consistence;  nor  is  there  formed 
around  the  ends  of  a fractured  bone,  a ring  fb  keep  them  ce- 
mented, as  was  the  opinion  of  Duhamel;  an  opinion  recently 
brought  forward  in  a work  in  which  the  author  seems  to  delight 


ON  MOTION. 


452 

in  reviving  errors  that  have  been  abandoned  for  ages.  Desti- 
tute of  nourishment,  dead  and  dried  up  in  this  artificial  necro- 
sis, the  sequestra  moves  in  the  centre  of  the  new  osseous  pro- 
duction, from  which  it  may  be  extracted  by  a perforation  made 
for  that  purpose.  It  is  owing  to  the  same  sympathy,  that  the 
dull  nocturnal  pains  which  are  occasioned  by  the  warmth  of  the 
bed,  in  patients  in  the  last  stages  of  the  veneral  affection,  and 
which  appear  to  have  their  seat  in  the  centre  of  the  long  bones, 
occasion  a swelling  of  these  bones  and  of  the  periosteum. 

The  use  of  the  periosteum  is  to  regulate  the  distribution  of 
the  nutritious  juices  of  bones,  since,  whenever  it  is  removed, 
granulations  arise,  in  an  irregular  manner,  on  the  spot  that  is 
bared.  This  quality  is,  besides,  common  to  all  fibrous  mem- 
branes whose  destruction  is  followed  by  excrescences  from  the 
organs  which  they  cover.  The  same  takes  place,  whenever  trees 
are  partially  stripped  of  their  bark.  It  has  been  erroneously 
believed,  that  the  periosteum,  in  the  same  way  as  the  bark  of 
plants,  contributes  to  the  growth  of  the  bones,  by  the  succes- 
sive induration  of  its  internal  laminae. 

The  marrow  which  fills  the  central  cavity  of  the  long  bones, 
and  the  medullary  fluid  contained  in  the  cells  of  the  spungy 
substance,  bear  the  greatest  analogy  to  adeps,  both  in  their 
chemical  composition  and  in  their  uses  (CVI).  The  propor- 
tion of  these  two  fluids  is  uniformly  relative.  In  very  thin  peo- 
ple, the  bones  contain  a marrow  that  is  thin  and  watery,  and 
though  this  fluid  alwa)  s fills  the  internal  cavities  of  these  or- 
gans, whose  solid  parietes  cannot  collapse,  it  contains  much 
fewer  particles  in  the  same  bulk:  and  its  quantity,  like  that  of 
the  fat,  is  in  fact  diminished.  It  is  the  product  of  arterial  exha- 
lation, and  does  not  serve  to  the  immediate  nutrition  of  the 
bone,  as  was  thought  by  the  ancients;  at  least,  it  does  not 
answer  that  purpose  solely;  for,  in  the  numerous  class  of  birds, 
the  bones  contain  cavities  for  air,  and  are  destitute  of  this  fluid. 
It  is  difficult  to  determine  the  use  of  the  marrow  and  of  the 
medullary  fluid;  may  they  not  answer  the  purpose  of  filling  the 
cavities  which  nature  has  formed  in  the  bones,  so  as  to  render 
them  lighter?  Does  a part  of  these  fluids  exude  through  the 
cartilages  of  the  Joints,  and  mix  with  the  synovia  to  increase  its 
quantity,  and  to  lessen  the  friction  of  the  articulating  surfaces? 


0N  MOTION. 


453 


If  this  transudation  may  take  place  after  death,  why  might 
it  not  take  place,  when  all  the  parts  are  in  a state  of  vital  warmth 
and  expansion.^ 

CLXXVII.  Of  the  articulations^  the  articulating  cartilages 
and  ligaments^  and  the  synovial  fiuid.  The  articulations  of  the 
different  parts  of  the  skeleton  are  not  all  intended  to  allow  of 
motion;  several,  as  the  serrated  and  squamous  sutures,  and  the 
gomphosis,  are  entirely  without  motion,  and  are,  on  that  ac- 
count, termed  synarthrosis.  All  the  other  articulations,  whether 
the  bones  are  in  immediate  contact  (diarthrosis  of  contiguity), 
whether  they  are  united  by  a substance  interposed  between  them 
(diarthrosis  of  continuity  or  amphiarthrosis),  are  endowed  with 
a certain  degree  of  mobility.  I shall  speak  merely  of  the  move- 
able  articulations;  whether  they  allow  of  extensive  motions  and 
in  every  direction  (diarthrosis  orbicularis)  or  whether  the  bones 
move  only  in  two  opposite  directions  (alternate  diarthrosis  or 
ginglymus)  by  forming  an  angle,  (angular  ginglymus),  or  by 
executing,  on  each  other,  motions  of  rotation  (lateral  gin- 
glymus). 

In  all  the  articulations,  the  osseous  surfaces  are  covered  by 
laminae  of  a substance  less  hard  than  that  of  the  bone.  These 
are  the  articulating  cartilages,  which  answer  the  two  purposes 
of  giving  to  the  ends  of  the  bones  the  degree  of  polish  rieces- 
sary  to  their  slipping  freely,  and  to  facilitate  motion,  by  the 
considerable  degree  of  elasticity  which  they  possess.  Morgagni 
has  shown,  that  of  all  animal  substances,  cartilages  possess  most 
elasticity;  their  structure  is  very  different  from  that  of  the  bones, 
even  when  these  are  yet  cartilaginous;  for,  these  articulating 
cartilages  do  not  become  ossified,  even  in  persons  greatly  ad- 
vanced in  years.*  They  are  formed  of  very  short  fibres  dis- 
posed according  to  the  length  of  the  bone,  strongly  compressed 
against  each  other,  and  united  by  other  fibres.  This  vertical 
direction  of  the  greatest  part  of  the  cartilaginous  fibres,  demon- 
strated by  Lassone,  is  very  favourable  to  their  elastic  re-action. 
The  capsular  ligament  is  reflected  over  them,  becomes  very 

* Sometimes,  however,  these  cartilages  are  destroyed;  the  denuded  hone 
then  becomes  polished  by  friction,  and  as  hard  as  ivory. 


454 


ON  MOTION. 


thin,  and  is  lost  in  their  perichondrium,  according  to  Bonn, 
Nesbith,  and  other  anatomists. 

Besides  the  cartilages  which  surround  the  extremities  of 
bones,  there  are  found,  in  certain  articulations,  fibro-cartilagi- 
nous  laminae  lying  between  the  articulating  surfaces.  These 
connecting  ligaments  may  be  observed  in  the  articulation  of  the 
lower  jaw  to  the  temporal  bones,  of  the  femur  with  the  tibia, 
and  of  the  sternum  with  the  clavicle;  and  all  such  articulations 
perform  a great  number  of  motions,  as  is  the  case  with  the  jaw, 
or  suffer  considerable  pressure,  as  the  joints  of  the  knee  and 
sternum.  The  latter,  which  has  a very  slight  degree  of  motion, 
being  the  point  in  which  terminate  all  the  efforts  of  the  upper 
extremity,  required  this  apparatus  to  lessen  the  effect  on  the 
trunk,  the  motion  that  is  given  being,  in  part,  lost  in  the  action 
of  the  articulating  cartilage. 

I shall  not  repeat  what  has  been  already  said  of  the  secretion 
of  the  fluid  that  lubricates  the  articulating  surfaces,  that  facili- 
tates their  motion  and  keeps  them  in  contact.  Its  quantity  is  in 
direct  ratio  of  the  extent  of  these  surfaces  and  of  the  membra- 
nous capsule  in  which  they  are  contained;  it  is,  likewise,  pro- 
portioned to  the  frequency  of  motion  which  each  articulation 
allows. 

Synovia  is  the  name  that  is  given  to  the  fluid  prepared  by  the 
glandulo-cellular  bodies  in  the  vicinity  of  the  articulations,  and 
secreted  by  the  membranous  capsules  which  surround  them, 
and  are  reflected  over  the  articulating  extremities  of  the  bones 
whose  cartilages  they  cover;  so  that,  as  was  shown  by  Bonn, 
about  the  middle  of  the  last  century,  these  extremities  cannot 
be  said  to  be  contained  within  the  cavity  of  the  capsule,  which 
is  closed,  in  every  direction,  any  more  than  the  abdominal  vis- 
cera within  that  of  the  peritoneum.  The  synovia  is  heavier  than 
common  water,  quite  colourless,  and  more  viscid  than  any  other 
animal  fluid.  It  contains  a considerable  quantity  of  albumine 
which,  according  to  Margueron,  who  first  gave  a tolerably  ac- 
curate analysis  of  synovia,  is  found  in  a particular  state,  and 
much  disposed  to  concrete  into  filaments,  on  the  addition  of 
acids.  Besides,  it  contains  muriate  and  carbonate  of  soda  and 
phosphate  of  lime,  the  whole  dissolved  in  water,  which  forms 
about  three  fourths  of  its  weight. 


ON  MOTION. 


455 


CLXXVIII-  Theory  of  Anchylosis.  Motion  may  be  con- 
sidered as  the  proper  stimulus  of  the  synovial  secretion;  and  a 
moveable  joint,  as  is  justly  observed  by  Grimaud,  is  as  a centre 
of  fluxion  towards  which  the  fluids  rush,  in  every  direction,  in 
consequence  of  the  irritation  which  friction  determines.  If  the 
joint  remains  long  without  motion,  the  synovia  is  secreted  in 
smaller  quantity,  and  this  lessens  gradually;  it  may  even  hap- 
pen that  the  articulating  surfaces,  remaining  long  absolutely 
motionless,  lose  their  moisture,  and  from  the  want  of  the  fluid 
which  should  lubricate  them,  bring  on  irritation  and  adhesive 
inflammation  in  each  other,  either  from  increased  action  of  the 
vessels  of  the  perichondrium,  or  as  is  believed  by  Nesbith, 
Bonn,  and  others,  from  an  inflammatory  state  of  the  fold,  which 
is  reflected  from  the  capsule  of  the  joint  over  the  ligament. 

This  is  the  manner  in  which  the  disease,  termed  anchylosis, 
comes  on;  a disease  improperly  ascribed  to  the  congestion  of 
the  soft  parts,  and  especially  of  the  ligaments  surrounding  the 
articulations.  In  fact,  when  in  a fracture  of  the  thigh,  or  leg, 
about  the  middle  of  the  length  of  one  of  these  bones,  and  con- 
sequently, at  the  greatest  possible  distance  from  the  knee  joint, 
the  circumstances  of  the  case  require  that  the  bandages  should 
be  kept  on  the  limb  a considerable  time,  the  joint  loses  its 
power  of  motion,  recovers  it  with  difficulty,  and  sometimes 
not  at  all.  I have  at  present  before  me,  the  case  of  a man  in 
whom  a scorbutic  affection  has  delayed,  to  such  a degree,  union 
of  the  bone,  after  a simple  fracture  of  the  femur,  about  the  mid- 
dle of  the  bone,  that  it  has  been  found  necessary  to  continue, 
for  seven  months,  the  use  of  splints.  In  the  course  of  so  long  a 
state  of  inaction,  the  soft  parts  have  lost  the  habit  of  moving, 
and  the  knee  is,  almost  completely,  anchylosed. 

Whenever  on  account  of  any  complaint,  one  has  been  confined 
to  bed,  the  first  attempts  to  walk  are  painful,  difficult,  and  at- 
tended by  a marked  crepitus  in  the  knee,  denoting  clearly  the 
want  of  synovia.  On  the  other  hand,  if  the  joint  is  examined 
in  a person  who  befoi'e  death  has  been  long  without  motion, 
the  articulating  surfaces  will  be  found  rough  and  dry,  with  evi- 
dent marks  of  inflammation.  Flajani  mentions  the  case  of  a 
patient  who  died  after  having  been  three  months  in  bed,  in  an 
almost  motionless  state.  Externally,  the  knees  did  not  appear 


456 


ON  MOTION. 


to  have  been  injured,  and  yet  he  could  not  bend  his  knee  joint. 
On  opening  the  joint,  it  was  found  that  the  articulating  surfaces 
has  grown  together;  the  posterior  part  of  the  patella  adhered  to 
the  condyles  of  the  femur,  and  it  was  necessary  to  use  a scalpel 
to  detach  these  parts  from  each  other.  I have  frequently  ob* 
served  the  same  appearance,  in  dissecting  the  knee  joint  of  per- 
sons who  died  while  labouring  under  white  swelling,  with  or 
without  ulceration.  The  anchylosis  which  invariably  attends 
this  affection,  evidently  arises  from  the  absolute  rest  of  the 
diseased  joint. 

Anchylosis  from  want  of  motion,  and  consequently  from  want 
of  synovia,  is  not  always  a partial  affection  limited  to  one  or 
two  joints;  sometimes  it  affects  several  at  once,  as  in  the  case 
of  the  patient  whose  skeleton  was  presented  by  M.  Larrey  to 
the  museum  of  the  School  of  Medicine  at  Paris.  One  of  the 
most  remarkable  cases  of  universal  anchtlosis  of  the  joints,  is 
that  lately  communicated  to  the  National  Institute  by  M.  Percy; 
the  patient  was  an  old  cavalry  officer,  who  was  subject  to  fits 
of  the  gout,  and  whose  articulations,  even  that  of  the  lower  jaw, 
became  stiff,  and  completely  lost  all  power  of  motion,  so  that, 
towards  the  latter  end  of  his  wretched  existence,  he  could  not 
be  moved  without  feeling  severe  pain  in  his  anchylosed  joints. 

From  this  explanation  may  be  conceived  the  advantage  of 
moving  the  lower  extremity,  when,  after  a fracture  of  the  leg, 
the  ends  of  the  bone  have  become  sufficiently’  united  to  prevent 
their  being  displaced.  These  motions,  which  are  of  indispen- 
sable necessity  in  all  fractures  of  the  femur,  of  the  tibia,  and 
especially  of  the  patella,  are  much  better  calculated  to  prevent 
alchylosis,  than  the  various  resolvent  remedies  which  are  com- 
monly employed,  as  plasters  of  soap,  vigo,  cicuta,  diabotanum, 
diachylon,  pumping,  bathing  and  fumigations,  which,  however, 
should  be  used  in  combination  with  a moderate  exercise  of  the 
limb,  in  order  to  obtain  the  most  complete  success. 

The  gout  affects  those  joints  which  are  most  subject  to  mo- 
tion, and  on  which  there  is  the  greatest  pressure.  The  first 
attacks,  as  Sydenham  observes,  come  on  in  the  joint  of  the 
great  toe  with  the  first  metatarsal  bone;  an  articulation  which 
bears  the  weight  of  the  whole  body,  and  which  is  most  called 
into  action,  in  the  various  motions  of  progression. 


ON  MOTION. 


457 


The  muscles  which  pass  over  the  joints  give  them  much 
greater  security  than  the  lateral  ligaments.  In  fact,  if  the  mus- 
cles become  palsied,  the  mere  weight  of  the  limb  stretches  the 
ligaments,  which  give  way,  become  elongated,  and  allow  the 
head  of  the  bone  to  escape  from  its  glenoid  cavity.  It  is,  in  this 
manner,  that  a loss  of  motion,  and  atrophy  of  the  deltoid  mus- 
cle, are  attended  with  a luxation  of  the  humerus;  the  orbicular 
ligament  of  the  articulation  of  this  bone  with  the  scapula,  being 
incapable  of  retaining  its  head  within  the  glenoid  cavity.  The 
spinal  column,  when  dissected  and  deprived  of  all  but  its  liga- 
mentous attachments,  gives  way  under  a weight  much  smaller 
than  that  which  it  would  have  supported,  before  being  stripped 
of  the  muscles  which  are  connected  with  it. 

CLXXIX.  Of  standing.  This  is  the  name  given  to  the 
action  by  which  man  holds  himself  upright  on  a solid  plane. 
In  this  erect  position  of  all  our  parts,  the  perpendicular  line, 
passing  through  the  centre  of  gravity*  of  the  body,  must  fall 
on  some  point  of  the  space  measured  by  the  soles  of  the  feet. 
Standing  is  most  firm,  when,  on  prolonging  the  line  of  the 
centre  of  gravity  of  the  body,  it  falls  on  the  base  of  sustenta- 
tion  (I  call  thus  the  space  defined  by  the  feet,  whether  close 
or  apart);  but  this  line  may  tend  to  exceed  it,  without  our 
necessarily  falling,  the  muscular  action  soon  restoring  the  equi- 
librium which  is  deranged  by  the  altered  direction  of  this  line. 
But  if  the  lower  extremity  of  the  line,  by  being  prolonged, 
should  fall  without  the  limits  of  the  base  of  sustentation,  a fall 
is  unavoidable  on  the  side  towards  which  this  line  inclinesf. 

If  the  body  is  inclined  backwards,  so  that  there  is  a danger 
of  a fall  on  the  occiput,  the  extensor  muscles  of  the  leg  contract 

* The  centre  of  gravity,  in  the  adult,  is  situated  between  the  sacrum  and 
pubis. 

■{■  “ ^uotiescunque  linea  propensionis  corporis  Iwmavi,  cadit  extra  uniits  pedis 
innixi  plantam  avt  extra  qnadrilaterum,  compreher.sum  d dnabus  plantis  pedum, 
impediri  ruina,  d quocumqiie  musculorum  conatu  non  potest.”  Borelli,  Prop.  140. 

The  firmness  of  the  attitude,  in  standing,  depends,  therefore,  in  part,  on  the 
breadth  of  the  feet  and  on  their  distance;  hence,  it  is  much  more  tottering 
when  we  stand  on  one  foot,  and  we  are,  under  such  circumstances,  obliged  to 
be  perpetually  struggling,  to  prevent  the  centre  of  gravity  from  falling  out  of 
the  narrow  limits  of  the  base  of  sustentation. 

3 M 


458 


ON  MOTION. 


powerfully,  to  prevent  the  thigh  from  bending,  while  other 
powers  bring  forward  the  upper  parts,  and  give  to  the  pro- 
longed line  of  the  centre  of  gravity  a different  direction;  and 
if,  in  proportion  as  the  extensors  of  the  leg  are  brought  into  ac- 
tion, its  inclination  be  increased  to  such  a degree,  that  nothing 
is  capable  of  keeping  up  the  body,  which  its  own  weight  tends 
to  bring  to  the  ground,  these  muscles,  by  amotion  proportioned 
to  the  quickness  of  the  fall,  will  increase  their  efforts  to  prevent 
it,  and  may  be  able,  in  that  violent  contraction,  to  snap  asunder 
the  patella,  as  I have  explained  in  a memoir  on  the  fractures  of 
that  bone. 

I think  it  useful  to  insist,  more  than  has  been  done  hitherto, 
on  the  mechanism  by  which  the  human  body  is  supported  in  the 
erect  posture;  for  a knowledge  of  that  mechanism  facilitates  the 
explanation  of  the  motions  of  progression.  To  walk,  or  to  run, 
the  body  must  be  upright;  now,  when  it  is  known  by  what  power 
the  centre  of  gravity  of  the  body  is  maintained  perpendicular 
on  the  plane  which  supports  it,  it  will  be  easy  to  understand  the 
different  ways  in  which  it  changes  its  place,  in  the  course  of 
locomotion. 

Let  us  first  inquire  into  the  question  so  long  agitated,  whether 
man  is  intended  to  support  himself  and  to  walk  on  his  four 
limbs,  in  the  early  period  of  his  existence  after  birth? 

CLXXX.  An  upright  position  would  be  to  man  a state  of 
rest,  if  his  head  were  in  a perfect  equilibrium  on  the  vertebral 
column,  and  if  the  laiter,  forming  the  axis  of  the  body  and  sup- 
porting equal!}',  in  every  direction,  the  weight  of  the  abdominal 
and  thoracic  viscera,  fell  perpendicularly  on  the  pelvis  placed 
horizontally;  and,  in  short,  if  the  bones  of  the  lower  extremities 
formed  columns  set  perpendicularly  under  their  superincum- 
bent w'eight;  but  not  one  of  these  circumstances  is  to  be  observed 
in  the  human  body:  the  articulation  of  the  head  does  not  corres- 
pond to  its  centre  of  gravity;  the  weight  of  the  thoracic  and  ab- 
dominal viscera,  and  of  the  parietes  of  the  cavities  in  w'hich 
they  are  contained,  rests,  almost  entirely,  on  the  anterior  part 
of  the  vertebral  column.  The  vertebral  column  is  supported  on 
an  inclined  base,  and  the  bones  of  the  inferior  extremities, 
which  are  connected  to  each  other  by  convex  and  slippery  sur- 
faces, are,  more  or  less,  inclined  towards  one  another.  It  is 


ON  MOTION. 


459 


therefore  necessary,  that  an  active  power*  watch  incessantly, 
to  prevent  the  fall  which  would  be  the  natural  consequence  of 
their  weight  and  direction. 

This  power  resides  in  the  extensor  muscles  which  keep  the 
parts  of  our  body  in  a state  of  extension,  the  more  perfect,  and 
which  render  our  erect  posture  the  firmer,  as  they  are  endowed 
with  a more  considerable  power  of  antagonism,  and  as  our  pafts 
are  naturally  less  disposed  to  flexion;  and,  besides,  as  we  have 
seen  (CLXVI.)  these  powers  are  not  sufficient  to  balance  those 
whose  action  is  directly  opposed  to  theirs. 

The  relative  weakness  of  the  extensor  muscles  is  not  the  only 
obstacle  which  renders  impossible  an  erect  posture,  at  an  early 
period  of  life.  Other  causes,  into  which  we  are  about  to  enter, 
concur  in  unfitting  the  new  born  child  for  the  exercise  of  that 
faculty. 

The  articulation  of  the  head  to  the  vertebral  column  being 
nearer  the  occiput  than  the  chin,  and  not  corresponding  to  its 
centre  of  gravity,  its  own  weight  is  sufficient  to  make  it  fall  on 
the  upper  part  of  the  chest.  It  is  the  more  disposed  to  fall  for- 
ward, from  its  greater  bulk,  and,  as  in  a new  born  child  the  head 
is  much  larger  in  proportion  than  the  other  parts  of  the  body, 
and  as  its  extensor  muscles  partake  of  the  greater  weakness  of 
that  set  of  muscles,  it  falls  on  the  fore  part  of  the  chest,  and  in 
its  fall  draws  the  body  after  it.  The  weight  of  the  thoracic  and 
abdominal  viscera  tends  to  produce  the  same  effect. 

* An  upright  posture  is  not,  in  all  animals,  as  it  is  in  man,  the  consequence 
of  an  effort.  This  is  proved  by  the  following  fact  observed  by  M.  Dumeril. 
The  sea  fowl,  and  especially  the  waders,  (Grallae,  Linn.)  as  herohs  and  storks, 
forced  to  live  in  the  midst  of  marshes  and  muddy  waters,  in  which  they  find 
the  fisnes  and  reptiles  on  which  they  feed,  have  long  since  afforded  matter  of 
surprize  to  naturalists,  by  the  length  of  time  they  can  remain  motionless  in  an 
erect  posture.  This  singular  power,  so  necessary  to  animals  obliged  to  exjtect 
their  prey,  more  from  chance  than  from  industry,  they  owe  to  a peculiar  con- 
formation of  the  articulation  between  the  leg  and  thigh.  The  articulating  sur- 
face of  the  thigh  bone,  as  M.  D imeril  had  an  opportunity  of  observing  in  a 
stork,  {Ardea  ciconia,  Linn.)  contains,  in  its  centre,  a depression,  into  which 
there  is  received  a projection  of  the  tibia.  To  enable  the  animal  to  bend  its  leg, 
that  projection  must  be  disengaged  from  the  depression  into  which  it  is  lodg- 
ed, and  this  is  resisted  by  several  ligaments  which  keep  the  leg  extended  in 
standing,  in  flying,  and  other  progressive  motions,  without  the  assistance  of 
the  extensor  muscles. 


46© 


1>N  MOTION. 


Growth  always  proceeds  from  the  upper  to  the  lower  parts, 
and  this  law,  which  operates  uniformly,  completely  eludes  every 
kind  of  mechanical  explanation.  It  is  otherwise,  with  regard  to 
the  effects  which  result  from  this  unequal  growth  in  respect  to 
the  erect  posture.  The  inferior  limbs,  which  serve  as  a base  to 
the  whole  edifice,  being  imperfectly  evolved  at  the  period  of 
birth,  the  upper  parts  placed  on  these  unsteady  foundations, 
must  necessarily  fall  and  bring  them  down  with  them. 

The  relative  weight  of  the  head,  of  the  thoracic  and  abdomi- 
nal viscera,  tends,  therefore,  to  bring  forwards  the  line  in  the 
direction  of  which  all  the  parts  of  the  body  press  on  the  plane 
which  supports  it,  and  this  line  should  be  exactly  perpendicular 
to  that  plane  to  enable  the  body  to  be  perfectly  erect:  the  fol- 
lowing fact  proves  this  assertion:  I have  observed,  that  children, 
whose  head  is  very  large,  whose  belly  projects,  and  whose  vis- 
cera are  loaded  with  fat,  have  much  difficulty  in  learning  to 
stand;  it  is  only  about  the  end  of  their  second  year,  that  they 
dare  trust  to  their  own  strength,  and  then  they  meet  with  fre- 
quent falls,  and  have  a continual  tendency  to  go  on  all  fours. 

The  vertebral  column,  in  the  child,  does  not  describe,  as  ia 
the  adult,  three  curves  alternately  placed  in  opposite  directions. 
It  is  almost  straight,  and  yet  presents  in  the  direction  of  its 
length  a slight  curvature,  the  concavity  of  which  looks  for- 
wards. This  incurvation,  which  depends  solely  on  the  flexion 
of  the  trunk  while  in  the  womb,  is  accordingly  more  marked, 
the  nearer  the  child  is  to  the  time  of  his  birth. 

It  is  well  knov/n  that  the  curvatures,  in  opposite  directions  to 
the  vertebral  column,  add  to  the  firmness  of  th,e  erect  posture, 
by  increasing  the  extent  of  the  space  within  which  the  centre  of 
gravity  may  move,  without  being  carried  beyond  its  limits. 
With  regard  to  that  use,  the  vertebral  column  may  be  consider- 
ed as  defined  by  tv/o  lines  drawn  from  the  anterior  and  poste- 
rior part  of  the  first  cervical  vertebra,  to  the  sacro  lumbari  sym- 
physis. These  two  lines,  very  near  to  each  other  at  their  upper 
part,  and  below,  at  a distance  from  each  other,  would  be  the 
chords  of  arcs  and  the  tangents  of  the  curves,  formed  by  the 
vertebral  column.  So  that  this  column  may  be  considered  as 
having  a fictitious  thickness  greatly  exceeding  its  real  bulk. 

In  the  new  born  child  the  want  of  alternate  curvatures  not 


ON  MOTION. 


461 

only  contracts  the  boundaries  within  which  the  centre  of  gravity 
may  be  varied,  but  the  direction  of  the  only  curvature  which 
exists,  favours  the  flexion  of  the  trunk,  and  consequently  the  in- 
clination forward  of  the  centre  of  gravity,  and  the  tendency  to 
fall  in  that  direction.  This  inflexion  of  the  vertebral  column  in 
the  foetus  and  in  the  young  child  resembles  that  observed  in 
several  quadrupeds.* 

The  disadvantage  resulting  from  the  want  of  alternate  curva- 
tures in  the  vertebral  column  of  the  child  is  further  increased  by 
the  total  absence  of  spinous  processes.  It  is  well  known,  that 
the  principal  use  of  these  projections,  is  to  place  the  power  at  a 
distance  from  the  centre  of  motion  of  the  vertebrae,  to  increase 
the  length  of  the  lever  by  which  it  acts  in  straightening  the 
trunk,  and  thereby  to  render  its  action  more  efficacious.  At  the 
period  of  birth,  the  vertebrae  have  no  spinous  processes;  they 
afterwards  grow  from  the  place  at  which  the  laminae  of  those 
bones  are  united,  by  means  of  a cartilaginous  substance,  which 
completes  the  posterior  part  of  the  vertebral  canal.  The  mus- 
cles destined  to  keep  the  trunk  erect,  weakened  by  its  constant 
flexion  during  gestation,  lose,  besides,  a great  deal  of  their 
power,  from  the  unfavourable  manner  in  which  they  are  applied 
to  the  part  on  which  they  are  to  act. 

The  flexion  of  the  head  does  not  depend  merely  on  its  very 
considerable  weight,  but,  likewise,  on  the  want  of  spinous  pro- 
cesses in  the  cervical  vertebrae;  since  the  principal  motions  of 
the  neck  are  performed,  not  so  much  by  articulation  with  the 
atlas,  as  by  the  union  of  the  other  cervical  vertebrae. 

The  pelvis  of  the  child  is  but  imperfectly  evolved,  and  its 
upper  outlet  very  oblique.  The  viscera,  which  are  afterwards  to 
be  contained  within  its  cavity,  are,  for  the  greater  part,  situated 
above  it.  This  obliquity  of  the  pelvis  would  require  a perpetual 
straightening  of  the  vertebral  column,  to  prevent  the  direction  of 

* This  curvature  is  very  distinctly  marked  in  swine.  The  back  of  these  ani- 
mals  is  remarkably  prominent,  and  this  form,  necessary  to  enable  the  vertebral 
column  to  support  the  immense  weight  of  their  abdominal  viscera,  has  a con- 
siderable influence  on  tlie  mechanism  of  their  motions  of  progression.  When 
frightened  by  any  noise,  they  spring  in  bounds,  and  it  is  easy  to  perceive  that, 
at  each  spring,  the  spine  becomes  arched  and  then  straightens  itself,  and  that 
their  motion  when  rapid  is  effected  by  the  alternate  tension  and  relaxation  of 
their  spinal  arch. 


462 


ON  MOTION. 


the  centre  of  gravity  from  obeying  its  natural  tendency  fonvard. 
On  the  other  hand,  the  vertebral  column,  resting  on  a narrow 
pelvis,  is  less  firmly  fixed,  and  may  more  readily  be  drawn 
beyond  the  limits  of  the  base  of  sustentation.  Lastly,  the  limited 
extent  of  the  pelvis,  together  with  its  obliquity,  causes  the  ill 
supported  abdominal  viscera  to  fall  on  the  anterior  and  inferior 
part  of  the  parietes  of  the  abdomen,  and  favours  the  fall  of  the 
body  in  the  same  direction. 

The  patella,  which  answers  the  double  purpose  of  giving 
firmness  to  the  knee  joint,  in  front  of  which  it  is  placed,  and  of 
increasing  the  power  of  the  muscles  of  the  leg,  by  placing  them 
at  a distance  from  the'  centre  of  motion  in  that  articulation,  and 
by  increasing  the  angle  at  which  they  are  inserted  into  the  tibia, 
as  yet  does  not  exist  in  new  boro  children.  The  tendinous  por- 
tion of  the  extensors  of  the  leg,  where  the  patella  is  hereafter  to 
be  formed,  is  merely  of  a more  condensed  tissue,  and  of  a car- 
tilaginous hardness. 

The  want  of  a fulcrum  is  attended  with  a continual  disposi- 
tion in  the  leg  to  bend  upon  the  thigh;  and  the  parallel  direc- 
tion of  its  extensor  muscles,  occasions  a complete  loss  of  their 
effective  power.  Then  their  antagonizing  muscles  induce  a 
flexion  of  that  limb,  which  is  the  more  considerable,  as  it  is  but 
imperfectly  limited  by  the  tendon  which  is  situated  at  the  fore 
part  of  the  knee. 

The  length  of  the  os  calcis,  the  extent  of  its  projection  beyond 
the  inferior  extremity  of  the  bones  of  the  leg,  tend  to  give  firm- 
ness to  the  erect  posture,  by  increasing  the  length  of  the  lever 
by  which  the  extensors  of  the  foot  act  on  the  heel;  and,  as  in 
the  new  born  child,  this  bone  is  shorter  and  less  projecting,  the 
power  of  these  muscles,  whose  insertion  is  very  near  the  centre 
of  motion  of  the  articulation  of  the  foot,  is  greatly  diminished. 

The  feet,  in  man,  are  broader  than  those  of  any  other  animal; 
and  to  this  breadth  of  the  surface  of  the  base  on  which  he  rests, 
he,  in  great  measure,  owes  the  advantage  of  being  able  to  sup- 
port, on  one  leg  or  on  both,  the  weight  of  his  body,  in  standing 
and  in  the  different  motions  of  progression;  while  the  other 
mammalia  cannot  support  themselves,  at  least  only  for  a very 
limited  time,  without  resting  on  three  of  their  extremities. 
When  I say  that  from  the  extent  of  his  feet,  the  body  of  man 


ON  MOTION. 


463 


does,  of  all  animals,  rest  on  the  broadest  surface,  I do  not  take 
into  account  the  space  which  those  parts  include  between  them 
when  apart  from  each  other.  In  fact,  the  space  which  is  measured 
by  the  feet,  is  much  greater  in  quadrupeds  than  in  man.  Nature" 
has  made  up  for  the  disadvantage  arising  out  of  the  smallness 
of  their  feet,  by  the  distance  at  which  they  are  placed;  and  if 
that  form  disables  them  from  standing  on  two  feet,  it  gives  firm- 
ness to  their  peculiar  mode  of  standing. 

The  feet  of  the  ourang  outang,  which,  in  the  general  struc- 
ture of  his  organs,  bears  so  striking  an  analogy  to  the  human 
species,  resemble  a coarsely  formed  hand,  better  fitted  to  clim|) 
the  trees  on  which  that  animal  seeks  his  food,  than  to  the  pur- 
poses to  which  man  applies  his  hands.  Thus  the  erect  posture 
which  he,  at  times,  assumes,  is  neither  the  most  convenient  nor 
the  most  natural  to  him.  And,  according  to  a philosopher,  who 
speaks  on  the  authority  of  several  travellers,  if  a sudden  danger 
obliges  him  to  make  his  escape,  or  to  leap,  he  drops  on  all  fours, 
and  discovers  his  real  origin;  he  is  reduced  to  his  own  condi- 
tion when  he  quits  that  unnatural  attitude,  and  discovers  in  him- 
self an  animal,  which,  like  many  a man,  has  no  better  quality  to 
recommend  him  than  a specious  disguise. 

The  feet  are  the  parts  least  developed  in  the  new-born  child; 
his  body  is  insecure  on  that  narrow  basis;  the  prolongation  of 
the  line  of  his  centre  of  gravity,  which  so  many  other  causes 
tend  to  carry  beyond  that  base,  will  be  the  more  inclined  to  fall 
beyond  it,  from  its  small  extent.  The  greater  number  of  the 
differences  which  have  just  been  examined,  depend  on  the  mode 
of  nutrition  in  the  foetus.  The  umbilical  arteries  bring  to  the 
mother  the  blood  which  the  aorta  carries  towards  the  lower  parts, 
and  only  a few  small  branches  are  sent  to  the  pelvis,  and  to  the 
lower  extremities.  Thus,  the  developement,  which  almost  uni- 
formly bears  a proportion  to  the  quantity  of  blood  sent  into 
organs,  is  but  imperfect  in  those  parts  at  the  time  of  birth, 
while  the  head  of  the  trunk  and  upper  extremities  are  evolved 
much  more  considerably. 

The  new  born  child,  therefore  resembles  quadrupeds  in  the 
physical  arrangement  of  his  organs.  This  analogy  is  the  more 
marked,  the  nearer  the  foetus  is  to  the  period  of  his  formation; 
and  it  might  be  laid  down  as  a general  proposition,  that  orga- 


464 


ON  MOTION. 


nized  beings  resemble  one  another  more  closely,  the  nearer  to 
the  period  of  incipient  existence  they  are  examined.  The  dif- 
ferences which  characterize  them  become  apparent,  in  propor- 
tion to  the  progress  of  evolution;  and  they  are  more  and  more 
distinct,  as  the  acts  of  life  are  repeated  in  the  organs  which  it 
animates. 

The  unequal  distribution  of  power  in  the  muscles,  and  the 
unfavourable  disposition  of  the  parts  to  which  these  powers  are 
applied,  render  it  impossible  for  the  infant  to  stand  upright;  that 
is,  to  keep  the  mean  line  of  direction  of  its  body  nearly  perpen- 
dicular to  the  plane  which  supports  it.  But  in  proportion  as  he 
advances  in  age,  the  preponderance  of  the  flexors  over  the  ex- 
tensors ceases  to  be  in  excess.  The  proportionate  size  of  the 
head,  and  of  the  thoracic  and  abdominal  viscera,  diminishes. 
The  curvatures  of  the  vertebral  column  begin  to  be  distinguish- 
able; the  spinous  processes  of  the  vertebrae  are  evolved;  the 
breadth  of  the  pelvis  is  increased,  and  its  obliquity  lessened;  the 
patella  becomes  ossified,  the  os  calcis  juts  out  backwards,  the 
relative  smallness  of  the  feet  ceases.  By  degrees  the  child  learns 
to  stand,  resting  on  both  or  only  on  one  of  his  feet;  his  eyes 
naturally  directed  towards  heaven,  a noble  prerogative,  which, 
if  one  might  believe  Ovid,*  is  possessed  by  man  alone  of  all  the 
animals. 

Man  is,  of  all  animals,  the  only  one  that  can  stand  upright, 
and  walk  in  that  attitude,  when  his  organs  are  suflBciently 
evolved.  Let  us  now  point  out  some  of  the  principal  causes  to 
which  that  privilege  is  to  be  ascribed. 

CLXXXI.  Though  the  articulation  of  the  head  to  the  cervi- 
cal column,  does  not  correspond  either  to  its  centre  of  magni- 
tude, or  to  its  centre  of  gravity;  and  though  it  is  nearer  to  the 
occiput  than  to  the  chin,  its  distance  from  the  latter  is  much 
smaller  in  man,  than  in  the  monkey  and  other  animals,  whose 
foramen  magnum  is,  according  to  Daubenton,  placed  nearest  to 
the  posterior  extremity  of  the  head,  when  they  resemble  man 

* Os  liomini  sublime  deJit,  calumqne  tueri 

Jusslt,  et  erectos  ad  sidera  tollere  vuUus. 

These  verses  may  be  much  more  justly  applied  to  the  fish,  called  by  natu- 
ralists Uranoscopus.  Its  eyes  are  turned  upwards,  and  constantly  look  towards 
the  heavens. 


ON  MOTION. 


465 


the  least.  The  head,  therefore,  is  very  nearly  in  equilibrio  on  the 
column  which  supports  it;  at  least  to  keep  it  in  that  position,  a 
very  slight  power  is  required;  while  the  head  of  a quadruped, 
which  has  a constant  tendency  towards  the  ground,  requires  to 
be  supported  by  a part  capable  of  a great  and  continued  resist- 
ance. This  purpose  is  answered  by  the  posterior  cervical  liga- 
ment, so  remarkable  in  those  animals,  attached  to  the  spinous 
processes  of  the  vertebrae,  and  to  the  protuberance  qf  the  occi- 
pital bone,  which  projects  much  more  in  them  than  in  the  human 
species,  in  whom  instead  of  a posterior  cervical  ligament,  there 
is  found  a mere  line  of  cellular  substance,  dividing  the  nape  of 
the  neck  into  two  equal  parts. 

The  alternate  curvatures  of  the  vertebral  column,  the  breadth 
of  the  pelvis  and  of  the  feet,  the  great  power  of  the  extensors  of 
the  foot  and  thigh,*  all  these  favourable  conditions  observable 
in  man,  are  wanting  in  animals;  but,  as  in  the  latter,  every 
thing  concurs  to  prevent  their  being  capable  of  standing  on  two 
feet,  in  man  every  thing  is  so  disposed,  as  to  render  it  very  diffi- 
cult for  him  to  rest  on  his  four  extremities.  In  fact,  indepen- 
dently of  the  great  inequality  which  there  is  between  his  upper 
and  lower  limbs,  a difference  of  length,  which,  being  less  sensi- 
ble in  early  life,  makes  it  less  uneasy  for  a child  to  walk  on  its 
hands  and  feet,  these  four  limbs  are  far  from  affording  the  body 
an  equally  solid  support.  The  eyes  being  naturally  forwards, 
are,  in  that  attitude,  directed  towards  the  earth,  and  do  not  em- 
brace a sufficient  space. 

We  cannot,  therefore,  agree  with  Barthez,  that  man,  during 
infancy,  is  naturally  a quadruped,  since  he  is  then  but  an  imper- 
fect biped  (CLXXX);  nor  can  we  admit  that  man  might  walk 
on  all  fours  all  his  life,  if  he  were  not  broken  of  the  bad  habit 
which  he  learns  in  infancy. 

CLXXXII.  Very  little  has  been  added  to  what  Galen  has 
said  in  his  admirable  work  on  the  structure  of  parts,  relative  to 
the  respective  advantages  attending  the  peculiar  conformation 
and  structure  of  the  upper  and  lower  limbs.  It  is  easy  to  see, 
that  in  combining,  as  much  as  possible,  strength  and  facility 

* These  muscles  form  the  calf  of  the  leg  and  the  buttocks;  in  no  animal  are 
these  masses  of  flesh  more  prominent  than  in  man. 

3 N 


ON  MOTION. 


466 

of  motion,  Nature  has  made  the  former  predominate  in  the 
structure  of  the  inferior  extremities;  while  she  has  sacrificed 
strength  to  facility,  to  precision,  to  extent,  and  rapidity  of  mo- 
tion, in  the  upper  extremities. 

To  convince  oneself  of  the  truth  of  what  has  been  stated,  it  is 
sufficient  to  compare,  under  the  two  relations*  of  the  resistance 
of  which  they  are  capable,  and  of  the  motions  which  they  allow, 
the  pelvis  to  the  shoulder,  the  thigh  to  the  humerus,  the  leg  to 
the  fore  arm,  and  the  foot  to  the  hand. 

The  inferior  extremities,  if  examined  when  the  bones  are 
covered  with  the  soft  parts,  will  present  the  appearance  of  an 
inverted  cone  or  pyramid,  which,  at  first  sight,  appears  con- 
trary to  the  object  which  nature  had  in  view;  but  if  the  bones 
be  stripped  of  their  fleshy  coverings,  these  solid  supports  will 
be  seen  to  represent  a pyramid,  whose  base  is  at  the  lowest 
part  and  formed  by  the  foot,  and  which  decreases  in  breadth 
upward  from  the  leg,  formed  by  the  union  of  two  bones, 
towards  the  thigh,  consisting  of  only  one  bone. 

If  it  be  asked  why  the  inferior  extremities  are  formed  of 
several  pieces,  detached  and  placed  one  above  the  other,  it  will 
be  found  that  they  are  thereby  much  more  solid,  than  if  formed 
of  one  bone;  since,  according  to  a theorem,  demonstrated  by 
Euler,f  two  columns  containing  the  same  quantity  of  matter 
and  of  equal  diameter,  have  each  a solidity  in  inverse  ratio  of 
the  squares  of  their  height:  in  other  words,  of  two  columns, 

* See  the  anatomical  observations  on  the  neck  of  the  Uiigh  bone,  which  1 
have  prefixed  to  a memoir  which  bears  the  title  of  Dissertation  anatomico-chi- 
rurgicale  sur  !es  fractures  <lu  col  du  femur.  Paris,  an  VII. 

f JHethodus  inveniendi  lineas  curvas. 

Nature  has,  therefore,  increased  the  number  of  these  columns  in  the  ex- 
tremities of  quadrupeds,  by  raising  their  heel  and  the  different  parts  of  the 
foot,  whose  bones  she  has  lengthened,  to  make  of  them  so  many  secondary 
legs.  These  numerous  columns  placed  above  one  another,  are  alternately 
inclined,  and  in  a state  of  habitual  flexion,  in  the  quadrupeds  remarkable 
for  swiftness  in  running  or  for  their  power  in  leaping,  as  in  the  hare  and 
squirrel;  while  in  the  ox,  and  especially  in  the  elephant,  they  are  all  plaocd 
verticall)',  so  that  the  enormous  mass  of  the  latter  rests  on  four  pillars,  the 
different  pieces  of  which  are  short,  and  so  slightly  moveable  on  one  another, 
that,  as  Barthez  observes.  Saint  Basil  has  adopted  the  error  of  Pliny,  .Dlian, 
and  several  other  writers  of  antiquity,  that  there  are  no  articulations  in  the 
legs  of  that  monstrous  animal. 


ON  MOTION.  457 

containing  the  same  materials,  of  equal  diameter,  and  of  une- 
qual height,  the  smaller  is  the  stronger. 

The  long  bones,  which  by  their  union  form  the  inferior  ex- 
tremity, contain  a cavity  which  adds  to  their  strength,  for  ac- 
cording to  another  theorem,  explained  by  Galileo,  two  hollow 
columns  of  the  same  quantity  of  matter,  of  the  same  weight  and 
length,  bear  to  each  other  a proportion  of  strength  measured  by 
the  diameter  of  their  internal  excavations. 

The  breadth  of  surface  of  the  articulations  of  the  inferior  ex- 
tremities, assists,  materially,  in  giving  them  additional  strength, 
when,  in  standing,  these  bones  are  in  a vertical  direction.  No 
articulation  has  a broader  surface  than  that  of  the  thigh  with 
the  leg  and  knee  pan.  Among  the  orbicular  articulations,  no 
one  has  more  points  cf  contact  than  the  joint  of  the  thigh  bone 
to  those  of  the  pelvis.  Professor  Barthez  says,  that  when  the 
body  is  erect,  the  head  of  the  thigh  bone  and  the  acetabulum 
of  the  os  innominatum,  which  receives  that  bone,  come  in  con- 
tact in  a surface  of  small  extent.  I am,  on  the  contrary,  of 
opinion  that  in  no  possible  case  can  the  contact  of  two  bones 
be  more  complete.  The  middle  line  of  direction  of  the  upper 
part  of  the  thigh  bone,  is  then  exactly  perpendicular  to  the  sur- 
face of  the  cond)'loid  cavity,  which  embraces  and  touches,  in 
nearly  every  point,  the  almost  spherical  head  of  that  bone. 

The  cervix  on  which  the  head  of  the  bone  is  placed,  by  keep- 
ing the  thigh  bone  at  a distance  from  the  cavity  of  the  pelvis, 
increases  the  extent  of  the  space,  in  which  the  centre  of  gravity 
may  vary  without  being  carried  beyond  its  limits. 

CLXXXIII.  The  erect  posture  does  not  imply  a perfect  ab- 
sence of  motion.  It  is,  on  the  contrary,  accompanied  by  a stag- 
gering which  is  the  more  marked  in  proportion  as  the  person 
has  less  strength  and  vigour.  These  perpetual  oscillations, 
though  but  slightly  distinct  in  a man  who  stands  upright,  depend 
on  the  incapacity  of  the  extensors  to  keep  up  a constant  state  of 
contraction,  so  that  they  become  relaxed  for  a short  time,  and 
the  intervals  of  rest  in  the  extensors  are  frequent,  in  propor- 
tion to  the  weaker  state  of  the  subject. 

Some  physiologists  have  given  a very  inaccurate  idea  of 
standing,  by  making  that  attitude  depend  on  a general  effort  of 
the  muscles;  the  extensors  only,  are  truly  active.  The  flexors. 


ON  MOTION. 


468 

far  from  assisting,  tend,  on  the  contrary,  to  disturb  the  relation 
between  the  bones,  necessary  to  render  that  state  permanent. 
This  explains,  why  standing  is  so  much  more  fatiguing  than 
walking,  in  which  the  extensors  and  flexors  of  the  limbs  arc 
in  alternate  action  and  rest. 

It  may  be  said,  nevertheless,  that  to  give  the  greater  firm- 
ness to  the  attitude,  we  sometimes  contract,  in  a moderate  de- 
gree, the  flexors  themselves;  then,  that  great  part  of  the  real 
force  of  the  muscles,  which  acts  according  to  the  direction  of 
the  levers  which  they  are  to  set  in  motion  (CLX V.)  and  which 
is  completely  lost  in  the  different  motions  which  they  produce, 
is  usefully  employed  in  drawing  together  the  articular  extre- 
mities; in  keeping  their  surfaces  firmly  applied  to  each  other, 
and  in  maintaining  their  exact  super-position  which  is  neces- 
sary to  the  erect  posture  of  the  body.  No  one  that  I know  of, 
had  taken  notice  of  this  employment  of  the  greater  portion  of 
our  muscular  power,  which  was  thought  completely  lost  by  the 
unfavourable  arrangement  of  our  organs  of  motion.  The  line, 
according  to  which  all  the  parts  of  the  body  bear  on  the  plane 
which  supports  them,  has  much  more  tendency  to  fall  forwards 
than  backwards;*  and  falls  forward  are  the  most  common  and 
the  easiest.  Thus,  nature  has  directed,  in  the  same  direction, 
the  motion  of  the  hands,  which  we  carry  forward  to  break  the 
force  of  our  falls,  to  prevent  too  violent  shocks,  and  to  lessen 
their  effect.  At  the  same  time,  she  has  provided  means  of  pro- 
tection towards  the  sides  which  the  hands  could  not  guard. 
She  has  given  more  thickness  to  the  back  part  of  the  skull;  the 
skin  which  covers  the  neck  and  back,  is  much  denser  than  that 
which  covers  the  fore  part  of  the  body;  The  scapula,  in  addi- 
tion to  the  ribs,  protects  the  posterior  part  of  the  chest.  The 
spinal  column  lies  along  the  whole  length  of  the  back;  the  bones 
of  the  pelvis  have  their  whole  breadth  turned  backward. 

Falls  are  the  more  serious,  as  they  occur  in  a more  perfect 
state  of  extension  of  the  articulations;  the  falls  of  a child  whose 

• This  tendency  is  much  less  distinct  in  tall  slender  men.  It  is  observed, 
that  they,  for  the  most  part,  stoop  in  walking',  less  from  the  habit  of  bending 
forward,  than  to  prevent  the  centre  of  gravity  from  falling  behind.  Pregnant 
■women,  dropsical  patients,  all  persons  who  have  much  embonpoint,  throw 
their  body  back,  from  an  opposite  and  easy  understood  reason. 


ON  MOTION. 


469 

limbs  are  in  an  habitual  state  of  flexion,  are  much  less  danger- 
ous than  those  of  a strong  and  powerful  adult,  whose  body  falls 
in  one  piece,  if  I may  be  allowed  that  expression.  The  falls 
which  skaiters  meet  with,  on  the  ice,  are  often  fatal  from  frac- 
ture of  the  skull,  which  placed  at  the  extremity  of  a long  lever 
formed  by  the  whole  body,  whose  articulations  are  on  the 
stretch,  strikes  the  slippery  and  solid  ice,  with  a momentum 
increased  by  the  quickness  of  the  fall. 

We  have  already  seen,  that  wading  fowls  remain  a long 
while  standing,  without  effort,  by  means  of  a peculiar  contri- 
vance in  the  articulation  of  the  tibia  to  the  thigh  bone;  but  all 
other  birds  are  obliged  to  employ  muscular  action  when  stand- 
ing, except  during  sleep.  The  greater  part,  it  is  well  known, 
roost  on  a branch  which  they  grasp  firmly  with  their  claws. 
Now,  this  constriction,  by  which  they  cling  to  their  support,  is 
a necessary  result  of  the  manner  in  which  the  tendons  of  the 
flexors  of  their  feet  descend  along  their  legs.  These  tendons 
pass  behind  the  articulation  of  the  heel;  a muscle  which  arises 
from  the  pubis  joins  them,  as  it  passes  in  front  of  the  knee,  so 
that  the  bird  has  but  to  give  way  to  his  weight,  and  the  joints, 
becoming  salient  on  the  side  along  which  the  tendons  run, 
stretch  and  pull  them,  and  make  them  act  upon  the  feet,  so  as 
to  draw  in  the  claws  to  clasp  tightly  the  branch  on  which  he  is 
perched.  Borelli  was  the  first  who  understood  distinctly  and 
explained  satisfactorily  this  phenomenon.* 

CLXXXIV.  Although  standing  on  both  feet  is  most  natural 
to  man,  he  is  able  to  stand  on  one;  but  the  posture  is  fatiguing, 
from  the  forced  inclination  of  the  body  to  the  side  of  the  leg 
which  supports  him,  and  the  effort  of  contraction  required  to 
keep  up  this  lateral  inflexion.  The  difficulty  increases  if,  in- 
stead of  resting  on  the  entire  sole,  we  chuse  to  stand  on  the 
heel  or  on  the  toe;  the  base  of  support  is  then  so  small,  that  no 
effort  is  sufficient  to  keep  the  centre  of  gravity,  long  together, 
in  the  requisite  situation. 

As  to  the  degree  of  separation  of  the  feet,  which  gives  the 
firmest  possible  stand,  it  depends  upon  their  length.  When  they 

* De  motu  animalium,  Prop.  150.  Qtiaeritur  quare  aves  stando,  ramis  arbo- 
rum  comprehensis,  quiescunt  et  dormiunt  absque  ruina.  Tab.  II.  fig.  7. 


ON  MOTION. 


470 

enclose  a perfect  square,  that  is,  M’hen,  taking  their  length  at 
nine  inches,  each  side  of  the  quadrilateral  figure  is  of  that 
measure,  the  stand  is  the  firmest  that  can  be  conceived.  Never- 
theless, we  are  far  from  keeping  or  taking  this  posture  to  pre- 
vent falls.  The  wrestler,  who  wants  to  throw  his  aDtagonist, 
strides  much  more;  but  then  he  loses  on  one  side  what  he 
gains  on  another;  and  if  he  stride  36  inches,  i n the  transversal 
line,  it  will  need  much  greater  force  to  overthrow  him  on  that 
side;  but  it  will  take  much  less  to  throw  him  forwards,  or  on 
his  back.  Wherefore,  one  of  the  great  principles  of  this  gym- 
nastic art.  is  to  bring  back  the  feet  to  a moderate  stride,  in  the 
line  of  the  effort  which  is  foreseen  to  require  resistance. 

There  is  some  resemblance  to  standing,  in  the  attitudes  of 
kneeling  and  sitting. 

In  the  first,  the  weight  of  the  body  bears  upon  the  knees,  and 
we  must  bring  back  the  body,  to  throw  the  centre  of  gravity  over 
the  middle  of  the  legs.  Accordingly,  if  we  have  nothing  before 
us  to  lean  on,  this  posture  is  extremely  distressing,  and  we  can- 
not long  keep  it  on.  I have  said,  in  another  work,  that  genu- 
flexion rendered  monks  very  liable  to  hernia;  the  abdominal  vis- 
cera being  pushed  against  the  anterior  and  lower  part  of  the  ab- 
domen by  the  throwing  back  of  the  body. 

In  sitting,  the  weight  of  the  body  bearing  on  the  tuberosities 
of  the  ischia,  there  is  much  less  effort  required  than  in  standing 
on  the  feet.  The  base  of  support  is  much  larger;  and  when  the 
back  leans,  almost  all  the  extensor  muscles  employed  in  stand- 
ing are  in  action. 

CLXXXV.  Of  the  recumbent  posture.  Decubitus.  All  the 
authors  who,  like  Borelli,  have  treated  professedly  of  the  ani- 
mal mechanism;  all  the  physiologists,  who,  like  Haller,  have  set 
forth,  in  some  detail,  the  mechanism  of  standing,  and  of  pro- 
gression, have  completely  passed  over  the  consideration  of  the 
human  body  in  repose,  left  to  its  own  weight,  in  lying  on  as 
horizontal  plane.  The  intention  of  the  following  observations  is 
to  fill  up  this  gap.  Let  us  consider,  at  setting  out,  that  lying  on 
an  horizontal  plane,  is  the  only  posture  in  which  all  the  locomo- 
tive muscles  recover  the  principle  of  their  contractility,  exhaust- 
ed by  exertion.  Standing  without  motion,  has  only  the  appear- 
ance of  repose,  and  the  unremitted  contractions  it  requires,  fa- 


ON  MOTI®Ni 


471 

tigue  the  muscular  organs,  more  than  the  alternate  contractions, 
by  which  the  various  motions  of  progression  are  carried  into 
effect. 

The  human  body,  stretched  on  an  horizontal  plane,  reposes 
in  four  positions,  as  it  lies  on  the  back,  the  belly,  or  one  or  other 
of  the  sides.  The  Latin  tongue  expresses  the  first  two  situations, 
by  the  terms  supine  and  prone.  It  has  no  particular  word  for 
lying  upon  the  side. 

Lying  upon  the  right  side  is  the  most  ordinary  posture  of 
sleep,  in  which  we  rest  most  pleasantly,  and  longest  together. 
There  are  very  few,  except  under  constraint  of  some  faulty  or- 
ganization, who  lie  on  the  other  side.  This  depends  on  two 
causes;  when  the  body  lies  on  the  left  side,  the  liver,  a bulky 
viscus,  very  heavy,  and  ill  steadied  in  the  right  hypochondrium, 
presses  with  all  its  weight  on  the  stomach,  and  draws  down  the 
diaphragm:  thence  ensues  an  uneasiness,  which  hinders  long 
continuance  of  sleep,  or  disturbs  it  with  distressing  dreams:  then 
the  human  stomanh  presents  a canal  in  which  the  course  of  its 
contents  is  obliquely  directed  from  above  downwards,  and  from 
left  to  right:  the  right  or  pyloric  orifice  of  the  stomach  is  much 
less  raised  than  its  left  or  cardiac  orifice;  lying  on  the  right  side 
favours,  therefore,  the  descent  of  aliments,  which,  to  pass  into 
the  intestines,  are  not  obliged  to  ascend  against  their  own 
weight,  as  they  must,  in  lying  on  the  left  side.  These  two  ana- 
tomical causes  exert  their  influence  on  the  generality  of  men; 
and  if  there  are  any  who  fall  into  the  habit  of  lying  on  the  left, 
one  may  safely  conjecture  some  vicious  organization,  or  some 
accidental  cause,  that  determines  them,  as  by  instinct,  to  this 
posture. 

Let  us  suppose  an  effusion  of  blood,  water,  or  pus  in  the  sac 
of  the  pleura  of  the  right  side.  The  patient  lies  oh  this  side, 
that  the  weight  of  his  body  may  not  oppose  the  dilatation  of  the 
sound  side  of  the  chest.  The  parietes  of  this  cavity  are  not 
equally  distant  from  its  axis;  the  pressure  of  the  body  on  the 
plane  of  support,  prevents  the  separation  of  the  ribs,  whether  as 
a mechanical  hindrance  to  the  displacement  of  these  bones,  or 
in  numbing  the  contractility  of  the  muscles  of  inspiration,  all 
more  or  less  compressed:  Now,  as  the  healthy  lung  must  sup- 
ply the  place  of  the  diseased,  nothing  could  be  more  in  the  way 


ON  MOTION. 


4,n 

than  to  produce,  on  that  side,  by  a bad  posture,  a constraint 
equal  to  that  occasioned  by  disease  on  the  other. 

It  has  long  been  imagined,  and  it  is  taught  still,  that,  in  tho- 
racic effusions,  patients  lie  on  the  side  of  the  effusion,  to  hinder 
the  effused  fluid  from  pressing  on  the  mediastinum,  and  pushing 
it  against  the  opposite  lung,  of  which  it  will  constrain  the  deve- 
lopment. The  following  experiments  show  clearly  enough  the 
error  of  such  a supposition: 

I have  several  times  produced  artificial  hydrothorax,  by  in- 
jecting, with  water,  the  chest  of  several  bodies,  through  a wound 
in  one  of  the  sides.  This  experiment  can  be  made' only  on  bodies 
in  which  the  lungs  are  free  from  adhesion  to  the  parietes  of  the 
chest,  and  the  number  is  smaller  than  might  be  imagined;  you 
may  introduce  in  this  way'  from  three  to  four  pints  of  water.  I 
afterwards  opened  carefully  the  opposite  side  of  the  chest:  the 
ribs  removed  and  the  lungs  displaced,  gave  room  to  see  distinc  tiy 
the  septum  of  the  mediastinum  stretched  from  the  vertebral 
column  to  the  sternum,  and  supporting,  wit,*^  our  yielding,  the 
weight  of  the  liquid,  v/hatever  might  be  the  posture  given  to 
the  body. 

It  is  for  the  sake  then,  evidently,  of  not  preventing  the  dilata- 
tion of  the  sound  part  of  the  respiratory  apparatus,  already  con- 
demned in  one  part  to  inaction,  that  patients,  in  thoracic  effu- 
sion, lie  constantly  on  the  side  of  the  effusion.  It  is  for  the  same 
motive,  to  which  we  may  add  that  of  not  increasing  the  pain  by 
dragging  downward  the  inflamed  pleura,  that  patients  in  pleu- 
risy lie  on  the  affected  side.  The  same  thing  happens  in  perip- 
neumonies;  in  a word,  in  all  diseased  affections  of  the  lungs 
and  parietes  of  the  chest. 

Lying  on  the  back,  which  is  unusual  in  health,  is  natural  in 
many  diseases.  It  commonly  indicates  more  or  less  weakness  of 
the  muscles  of  inspiration.  The  contractile  powers  which  per- 
form the  dilatation  of  the  chest,  when  affected  with  adynamia, 
in  fevers  of  a bad  character,  or  after  extreme  fatigue,  carry  very 
imperfectly  into  effect  this  dilatation.  Nevertheless,  a deter- 
minate quantity  of  atmospherical  air  must  be  admitted,  every 
moment,  into  the  lungs,  and  the  general  weakness  would  be 
increased,  if  respiration  did  not  impregnate  the  blood  with  a 
sufficiency  of  oxygen:  patients  choose,  therefore,  the  posture 


ON  MOTION. 


473 

which  makes  the  dilatation  of  the  lungs  easiest  for  their  weak- 
ened iTiuscles.  The  posterior  parietes  of  the  chest,  on  which  the 
body  reposes,  in  lying  upon  the  back,  is  almost  useless  in  the 
expansion  of  the  cavity.  The  ribs,  which  have  the  centre  of 
their  motions  in  their  articulation  with  the  vertebral  column, 
are  almost  immoveable  backwards,  and  the  moveableness  of 
these  bones,  increases  with  the  length  of  the  lever  which  they 
represent;  so  that  no  where  is  it  greater  than  at  the  anterior 
extremity  terminating  in  the  sternum.  Thus,  lying  on  the  back 
has  the  double  advantage  of  not  constraining  any  of  the  mus- 
cles of  inspiration,  and  of  not  opposing  the  motion  of  the  ribs, 
except  at  that  part  where  these  bones  have  the  least  play;  lying 
on  the  back  is  one  of  the  characteristic  symptoms  of  putrid  or 
adynamic  fever,  of  scurvy,  and  of  all  the  diseases  of  which  de- 
bility of  the  contractile  parts  forms  the  principal  characteristic. 
After  the  fatigue  of  a long  march,  or  of  any  other  continued 
exertion,  we  take  this  position  in  lying,  and  change  it  only  when 
sleep  has  sufficiently  replaced  the  loss  of  contractility. 

Lying  on  the  belly  has  effects  directly  the  reverse.  The 
expansion  of  the  chest  is  hindered  exactly  where  the  bony 
structure  is  formed  for  the  greatest  play  of  motion:  the  abdo- 
minal viscera  are  besides  pushed  up  on  the  diaphragm,  of  which 
they  resist  the  depression,  and  the  posture  is  accordingly  un- 
usual. The  continuance  of  it  during  sleep  is  possible  only  to 
the  robust:  others,  even  when  they  do  fall  asleep  in  this  posture, 
soon  awake  from  troubled  and  distressing  dreams,  under  the 
agony  known  by  the  name  of  the  night-mare.  We  sometimes 
seek  this  posture  to  constrain  respiration,  and  so  abate  inward 
excitation,  in  the  ardour,  for  instance,  of  a febrile  paroxysm. 

The  different  postures  of  lying  having  reference  to  the  de- 
grees of  facility  of  respiration,  very  young  children  and  persons 
advanced  in  years,  prefer  lying  on  the  back;  this  posture  being, 
as  was  already  observed,  the  most  favourable  to  the  motions  of 
respiration.  Respiration,  like  all  the  other  functions  of  the  ani- 
mal economy,  with  the  exception  of  the  circulation  and  of  the 
phenomena  which  immediately  depend  on  it,  requires  a kind  of 
cultivation;  it  is  but  feebly  performed  at  an  early  period  of  life. 
It  is  only  after  a certain  number  of  years,  and  when  the  muscles 
of  respiration,  at  first  small  and  weak,  acquire  strength  from 

3 O 


ON  MOTION. 


474 

the  very  circumstance  of  being  called  into  frequent  action,  that 
the  chest  dilates  with  facility,  and  that  the  lungs  enjoy  the  full 
exercise  to  their  faculties.  Until  that  period,  the  enlargement 
of  the  chest  and  the  dilatation  of  the  lungs  took  place  in  an  im- 
perfect manner;  the  child  was  unable,  even  by  spitting,  to  free 
itself  of  the  mucus  with  which  its  bronchiae  are  apt  to  get  filled, 
and  which  render  the  pulmonary  catarrh,  called  the  hooping 
cough,  so  dangerous  at  an  early  period  of  life.  In  like  manner, 
in  an  old  man,  the  muscles,  debilitated,  and  returned  to  the  re- 
lative weakness  of  infancy,  in  vain  strive  to  clear  the  air  cells  of 
the  mucus  with  which  they  become  obstructed  in  the  suffocating 
catarrh.  The  mechanical  process  of  respiration  is,  therefore, 
equally  difficult  in  the  child,  from  the  weakness  of  the  muscles 
which  have  remained  in  a long  continued  state  of  inactivity;  in 
the  old  man,  from  the  debility  of  the  same  organs  and  from  the 
induration  of  the  cartilages.  Thus,  at  those  two  distant  periods 
of  life,  it  is  most  natural  to  lie  on  one’s  back,  but  there  is  a suf- 
ficiently remarkable  difference  in  that  respect,  and  which  may 
now  be  inquired  into. 

In  the  foregoing  observations,  I have  always  spoken  of  the 
human  body  as  stretched  on  a perfectly  horizontal  plane.  It  is 
seldom,  however,  that  we  rest  on  such  a surface;  almost  every 
one,  and  especially  persons  advanced  in  life,  require  that  the 
plane  should  be  inclined,  and  that  the  head  should  be  raised  to 
a certain  degree,  else  the  brain  would  become  affected  with  a 
fatal  congestion  of  blood.  Children,  on  the  other  hand,  suffer 
no  inconvenience  from  a neglect  of  this  precaution;  whether  it 
is  that  in  them,  the  vital  power  has  more  energy,  and  thus  ba- 
lances better  the  laws  of  mechanics,  by  opposing  more  power- 
fully the  effects  of  gravitation;  or  whether  it  is,  that  in  very 
young  children,  the  parietes  of  the  arteries  within  the  skull, 
have  a proportionate  thickness,  and  consequently  greater  power. 
The  extreme  disproportion  observable  in  adults,  in  the  thick- 
ness of  the  parietes,  between  the  cerebral  arteries  and  those  of 
other  parts  of  the  body,  is  but  trifling  in  children;  and  may  not 
this  difference  of  structure,  which  I have  several  times  observ- 
ed in  the  course  of  dissection,  be  considered  as  one  of  the 
principal  causes  which,  in  old  age,  bring  on  apoplexy,  a disease 
to  which  the  child  is  not  liable. 


ON  MOTION, 


47S 

It  is  well  known,  that  as  the  enlargement  of  the  chest  is  pro- 
duced by  the  depression  of  the  diaphragm,  persons  who  have 
taken  a plentiful  meal,  dropsical  patients,  pregnant  women,  can- 
not rest  without  lying  on  a very  inclined  plane;  so  that  the  chest 
being  considerably  raised,  and  the  patient,  as  it  were,  seated, 
the  weight  of  the  abdominal  viscera  draws  them  towards  the 
most  depending  part,  that  their  bulk  may  not  interfere  with  the 
depression  of  the  diaphragm. 

We  might  now  inquire  what  is  the  posture  in  which  the  body 
rests  with  least  fatigue;  this  investigation,  unimportant  to  the 
physician,  would  be  of  the  highest  value  to  the  arts,  which  have 
for  their  object  the  imitation  of  nature.  In  consequence  of 
ignorance  on  this  subject,  we  often  see,  in  the  works  of  several 
of  our  sculptors,  figures  in  attitudes  of  repose  so  incorrect  and 
uneasy,  that  they  could  not  maintain  them  without  considerable 
effort  and  fatigue. 

CLXXXVI.  Of  the  motions  of  progression.  Of  walking. 
Walking,  running,  and  leaping,  are  so  closely  connected,  that  it 
is  difficult  to  distinguish  them.  There  is,  in  fact,  very  little  dif- 
ference between  walking,  in  a certain  manner,  or  running;  and 
running  is  most  frequently  produced  by  the  complicated  me- 
chanism of  running  and  leaping.  In  the  most  natural  way  of 
walking,  we,  in  the  first  instance,  poise  the  body  on  one  foot: 
then,  bending  the  opposite  foot  on  the  leg,  the  latter  on  the 
thigh,  and  the  thigh  on  the  pelvis,  we  shorten  that  extremity; 
we,  at  the  same  time,  carry  it  forward,  extend  its  articulations, 
which  were  bent,  and  when  firmly  applied  to  the  ground,  we 
bend  the  body  forward,  and  carry  back  the  centre  of  gravity  in. 
that  direction;  and  performing  the  same  motions  with  the  limb 
which  remained  behind,  we  measure  the  space  the  more  rapidly, 
cseteris  paribus,  as  the  levers,  on  which  the  centre  of  gravity 
alternately  bears,  are  longer.  The  weight  of  the  body,  compared 
to  that  of  the  lower  extremities,  is. as  that  of  a carriage,  which 
moves,  in  succession,  on  the  different  spokes  of  its  wheels. 

The  centre  of  gravity  does  not  move  along  a straight  line,  but 
between  two  parallels,  in  which  space  it  describes  oblique  lines 
from  the  one  parallel  to  the  other,  and  forms  zig-zags.  The 
oblique  direction  of  the  neck  of  the  thigh  bones,  accounts  for  the 
lateral  oscillations  of  the  body  when  we  walk;  the  arms  which 


ON  MOTION. 


476 

move,  in  a different  direction  from  that  of  the  lower  extremi- 
ties, serve  to  balance  us,  preserve  the  equilibrium,  and  correct 
the  staggering,  which  would  be  much  greater,  if  the  neck  of  the 
thigh  bone,  instead  of  being  oblique,  had  been  horizontal.  The 
impulses  communicated  to  the  trunk,  are  reciprocally  balanced, 
and  the  latter  moves  in  the  diagonal  of  a parallelogram,  whose 
sides  are  represented  by  the  line  of  these  impulses.  We  con- 
stantly deviate  from  the  straight  line  in  walking;  and  if  the  sight 
did  not  enable  us  to  see,  at  a distance,  the  object  towards  which 
we  are  moving,  we  should  go  to  a considerable  distance  from  it. 
If  you  place  a man,  with  his  eyes  blind  folded,  in  the  middle  of 
a square  field,  he  will,  in  his  attempt  to  get  out,  and  thinking 
that  he  is  moving  in  a straight  line,  make  for  one  of  the  corners. 
It  is,  almost  always,  towards  the  left  that  we  deviate;  the  right 
lov/er  extremity,  which  is  the  stronger,  inclining  the  body 
towards  the  opposite  side.  Those  who  are  lame  depart  much 
more  from  a straight  line,  and  deviate  towards  the  side  of  the 
shorter  leg.  The  motions  which  they  are  obliged  to  use,  and 
which  render  their  gait  so  remarkable,  are  occasioned  by  the 
necessity  of  incessant  and  powerful  efforts,  to  prevent  the  body 
from  giving  way  to  its  own  weight,  and  to  the  greater  power  of 
the  sound  extremity,  whichinclines.it  towards  the  affected  side. 

The  breadth  of  the  feet,  and  a moderate  separation  of  these 
parts  give  a much  firmer  support  to  the  centre  of  gravity.  Thus, 
in  walking  on  a moving  and  insecure  surface,  we  hold  apart 
our  feet,  so  as  to  include  a greater  base  of  sustentation.  Those 
who  have  long  been  at  sea,  acquire  such  a habit  of  holding  their 
feet  asunder,  in  the  way  they  are  obliged  to  do  during  the 
rolling  of  a ship,  that  they  cannot  lose  the  habit  even  when  on 
shore,  and  are  easily  recognised  by  their  gait.  A sailor  is  unfit 
for  active  service,  till  he  has  acquired  what  is  called,  by  sea- 
faring people,  a seaman’s  foot;  that  is,  till  he  is  capable  of  step- 
ping firmly  on  the  deck  of  a vessel  tossed  by  the  tempest. 

The  gait  of  a woman,  from  her  having  smaller  feet,  is  less 
firm;  but  ought  we,  from  that  circumstance,  to  infer,  with  the 
most  eloquent  writer  of  the  eighteenth  century,  that  this  dimi- 
nutive size  of  the  foot,  is  connected  with  the  necessity  of  her 
being  overtaken  in  flight.  The  concave  form  of  the  sole  of  the 
feet,  by  enabling  them  better  to  adapt  themselves  to  the  uneven- 


ON  MOTION. 


477 

ness  of  the  soil,  concurs  in  giving  a firmer  footing  in  walking,  and 
In  other  motions  of  progression.  There  is,  in  walking,  an  inter- 
mediate moment,  between  the  beginning  and  end  of  a step, 
during  which  the  centre  of  gravity  is  in  the  air;  this  lasts  from 
the  moment  when  the  centre  of  gravity  is  no  longer  in  the  foot 
which  remains  behind,  till  it  returns  into  the  other  foot  which 
is  carried  forward. 

Walking  is  modified,  according  as  it  takes  place  on  a hori- 
zontal or  an  inclined  plane;  in  the  latter  case,  we  ascend  or 
descend,  and  the  exertion  is  much  more  fatiguing.  To  explain 
the  action  of  ascending,  let  us  suppose  a man  at  the  bottom  of  a 
flight  of  stairs,  which  he  wishes  to  go  up;  he  begins  by  bending 
the  articulations  of  the  limb  which  he  is  desirous  of  carrying 
forward;  he  raises  it  thus,  and  shortens  it  to  advance;  and  when 
the  foot,  which  is  in  a state  of  semi-extension,  rests  on  the 
ground,  he  extends  the  articulations  of  the  other  extremity, 
carries  thus  the  body  upward,  in  a vertical  direction,  and  com- 
pletes this  first  step,  by  contracting  the  extensors  of  the  leg  that 
were  first  in  action,  so  that  they  may  bring  forward  and  restore 
to  it  the  centre  of  gravity,  to  which  the  posterior  leg,  whose 
foot  is  extended,  has  given  a vertical  motion  of  elevation. 
Hence,  in  ascending,  the  calves  of  the  legs  and  knees,  especially 
the  latter,  are  so  much  fatigued;  for,  the  effort  with  which  the 
extensors  of  the  foremost  leg,  bring  back  again  upon  it  the  centre 
of  gravity,  is  more  powerful  than  that  by  which  the  gemelli  and 
the  soleus  impart  to  it,  by  extending  the  hindmost  foot,  a mo- 
tion of  vertical  elevation. 

To  relieve  the  extensors  of  the  leg,  we  bend  the  body  for- 
ward as  much  as  possible;  we  lean  back,  on  the  contrary,  in 
descending  a flight  of  stairs,  or  a rapid  slope,  in  order  to  slacken 
the  motion  by  which  the  body,  yielding  to  its  own  weight,  falls 
on  the  leg  that  is  carried  forward. 

At  the  moment  when  the  centre  of  gravity  is  no  longer 
within  -the  base  of  sustentation,  all  the  powers  unite  in  action, 
that  it  may  fall,  as  little  as  possible,  from  a vertical  direction. 
The  glutaei  steady  the  pelvis,  and  straighten  the  thigh;  the 
lumbar  muscles  extend  the  trunk  on  the  pelvis;  hence,  in  going 
down  a slope,  the  loins  get  so  much  fatigued.  We  are  less 
fatigued  in  going  down  hill,  when  the  slope  is  moderate,  than 


478 


ON  MOTION. 


in  going  up  hill;  as  the  force  of  gravitation,  or  the  weight  of  the 
body,  assists  considerably  the  descending  vertical  motion.  The 
motion  of  walking,  when  we  take  very  long  steps,  resembles 
that  of  going  up  hill,  as  the  body  being  lowered,  every  time  the 
legs  are  much  apart,  requires  to  be  elevated,  at  each  step, 
towards  the  foremost  leg. 

At  every  step  we  take,  the  articulation  of  the  leg  with  the 
foot  is  the  principal  seat  of  an  effort,  to  which  physiologists 
have  not  paid  any  attention.  The  whole  weight  of  the  body  is 
supported  by  the  action  of  the  levator  muscles  of  the  heel,  and 
the  astragalus  supports  this  weight,  which  varies  according  to 
the  corpulence  of  the  person,  and  the  burthen  with  which  he  is 
loaded.  The  weight  of  an  adult,  of  common  stature  and  of 
moderate  size,  may  be  estimated  at  about  150  pounds;  but 
which  sometimes,  in  corpulent  people,  amounts  to  between  four 
and  five  hundred  pounds.  If,  then,  to  the  weight  of  the  body 
there  be  added  that  of  the  burthen  which  it  may  support,  it 
will  be  conceived  how  immense  the  efforts  must  be,  which  are, 
as  it  were,  unconsciously  carried  on,  in  the  articulation  of  the 
foot  with  the  leg.  But  how  numerous  the  resources  which 
nature  has  provided  to  overcome  this  great  resistance;  how 
many  the  circumstances  she  has  happily  combined  to  accom- 
plish this  without  fatigue!  In  the  first  place,  the  foot  in  this 
action  represents  a lever  of  the  second  class,  and  this  lever,  it 
is  well  known,  it  the  mosv  advantageous,  the  resistance  being 
always  nearer  to  the  fulcrum  than  the  power,  and  the  arm,  by 
which  the  latter  acts,  consisting  of  the  whole  length  of  the  lever. 
If  you  attend  to  the  mechanism  of  the  different  parts  of  the 
skeleton,  you  will  no  where  find  so  powerful  a lever  applied  in 
so  favourable  a manner.  The  os  calcis,  by  carrying  the  foot 
beyond  its  articulation  with  the  leg,  adds  likewise  to  the  length 
of  the  lever  by  which  the  power  acts.  Its  length  has  consider- 
able influence  on  our  strength,  on  our  power  of  taking,  without 
fatigue,  long  walks,  or  engaging  in  exertions  requiring  con- 
siderable muscular  force  in  the  lower  extremities.  The  negroes, 
who  excel  in  running,  in  dancing,  and  in  all  gymnastic  exercises, 
have  a longer  and  more  projecting  heel  than  Europeans.  They 
dance  best,  whose  tendo  Achillis  is  most  detached,  that  is  to 
say,  projecting,  and  at  the  greatest  distance  from  the  axis  of 


ON  MOTION.  4yg 

the  leg;  which  implies,  that  its  lower  attachment  is  carried 
back,  by  the  prolongation  of  the  os  calcis. 

Those  who  have  a short  heel,  have  a long  and  flat  foot;  this 
conformation,  which,  when  marked,  is  faultv,  is  not  only  un- 
favourable to  beauty  of  form,  but  is  besides,  remarkably  inju- 
rious to  the  strength  of  the  limb,  as  well  as  to  freedom  of  motion. 
Men  with  flat  feet  are  always  bad  walkers;  hence,  this  flattened 
form,  when  very  considerable,  is  considered  as  unfitting  a man 
for  military  service.  Lastly,  the  term  denoting  this  physical 
imperfection  {pteds  plats')^  is  accounted  insulting  in  the  French 
language,  as  well  as  in  several  others.  But  let  us  go  on  with 
our  inquiry  into  the  advantageous  disposition  of  the  articulation 
of  the  foot  with  the  leg,  for  facility  in  walking,  and  in  the  dif- 
ferent motions  of  progression. 

We  have  seen-  that  the  tendons  are  generally  inserted  at  a 
very  acute  angle,  into  the  bones  on  which  they  act;  in  the  pres- 
sent  instance,  however,  the  insertion  takes  place  at  a right  angle, 
the  common  tendon  of  the  muscles  of  the  calf  of  the  leg  joining 
the  os  calcis,  at  the  angle  most  favourable  to  their  freedom  of 
action.  With  the  exception  of  the  muscles  which  move  the 
head  and  lower  jaw,  no  others  are  so  evidently  disposed  with 
this  purpose.  Nature  has  not  been  contented  with  forming  the 
foot  in  such  a manner  as  to  afford  the  most  advantageous  lever, 
to  which  the  moving  powers  are  applied,  at  the  greatest  pos- 
sible distance  from  the  fulcrum  and  at  the  angle  most  favour- 
able to  their  action;  she  has  further  increased  the  efficacy  of 
this  action,  by  adding  extraordinarily  to  the  number  of  muscu- 
lar fibres.  There  is  not,  in  the  body,  a stronger  muscle  than 
the  soleus,  whose  short  and  oblique  fibres  between  the  two  wide 
aponeuroses  which  cover  its  anterior  and  posterior  surfaces,  are 
more  numerous  than  in  any  other  muscle,  as  may  be  conceived, 
by  considering  the  extensive  surfaces  to  which  they  are  attached. 
Besides,  the  tendo  Achillis  is  kept  in  a due  degree  of  straight- 
ness, by  the  aponeurosis  of  the  leg  behind  it. 

Every  thing,  in  the  powers,  as  well  as  in  the  levers,  is  formed 
so  as  to  overcome  the  resistance,  without  difficulty;  that  is,  so 
as  to  raise  the  weight  of  the  body,  by  the  extension  of  the  foot, 
the  end  of  which  rests  on  the  ground,  in  every  motion  of  pro- 
gression. 


ON  MOTION. 


480 

This  immense  power  with  which  the  muscles  of  the  calf  of 
the  leg  act  to  raise  the  heel,  and  to  support  the  whole  weight  of 
the  body  resting  on  the  astragalus,  accounts  for  the  possibility 
of  transverse  fractures  of  the  os  calcis,  and  for  the  rupture  of 
the  tendo  Achillis,  notwithstanding  its  great  thickness;  and 
should  lead  one  not  to  allow  patients,  after  such  accidents,  to 
walk  freely,  for  several  months;  the  substance  which  unites  the 
parts  being  liable  to  rupture,  as  known  to  have  been  the  case 
in  several  instances.  This  same  arrangement  of  parts  likewise 
accounts  for  an- accident,  which  physiologists  have  long  endea- 
voured to  explain  by  a very  unsatisfactory  theory. 

It  not  unfrequently  happens,  that  the  mere  effort  of  walking 
occasions  a rupture  of  some  of  the  fibres  of  the  gemelli  and  of 
the  soleus,  in  consequence  of  which,  there  comes  on  pain, 
attended  with  induration  of  the  muscles,  and  with  a certain 
degree  of  ecchyraosis,  occasioned  by  the  extravasation  of  blood. 
Pathologists  suppose  these  symptoms  to  depend  on  a rupture  of 
the  plantaris  muscle;  this  rupture,  however,  is  hypothetical,  has 
never  been  proved  by  experience  to  exist,  and  its  supposed 
symptoms  are  altogether  idle  and  fallacious. 

I could,  if  it  were  not  out  of  place,  bring  forward  several 
cases  of  this  affection;  in  all  the  cases  which  have  come  under 
my  own  observation,  the  use  of  the  bath,  of  emollient  and 
slightly  narcotic  poultices,  but  above  all,  continued  rest,  while 
the  symptoms  lasted,  have  appeared  to  me  the  most  appropriate 
remedies. 

CLXXXVII.  Of  running.  In  running,  the  foot  that  is  hind- 
most being  raised  before  that  which  is  foremost  be  firmly  applied  * 
to  the  ground,  the  centre  of  gravity  is,  for  a moment,  suspended, 
and  moves  in  the  air,  impelled  by  the  force  of  projection,  the 
action  of  which  principally  constitutes  leaping. 

The  mechanism  of  running  is  a compound  of  that  of  walk- 
ing and  leaping,  but  resembling  most  the  latter;  hence  some 
authors  have  defined  it  to  consist  of  a succession  of  low  leaps. 
The  steps  are  not  longer  than  in  walking,  but  merely  succeed 
each  other  with  greater  velocity.  The  centre  of  gravitv  is  trans- 
ferred, with  more  rapidity,  from  one  leg  to  the  other,  and  faHs 
are  much  more  apt  to  take  place.  The  quick  repetition  of  the 
same  motions,  in  running,  requires  a very  lively  contractility  in 


ON  MOTION. 


481 

the  muscles  which  move  the  extremities,  and  as  the  energy  of 
this  vital  property  is  proportioned  to  the  extent  of  respiration, 
to  the  quantity  of  air  which  the  blood  acquires  in  passing 
through  the  lungsj  in  running  we  pant  and  breath  frequently, 
and  at  short  intervals,  without  any  particular  enlargement  of 
the  chest  at  each  act  of  respiration.  It  was  necessary  that  the 
parietes  of  this  cavity  should,  in  running,  be  remarkably  fixed; 
for,  it  becomes  the  point  on  which  those  muscles  are  inserted 
which  steady  the  pelvis  and  loins,  and  prevented  their  yielding  an 
unsteady  basis  to  the  lower  extremities.  The  best  runners  are 
those  who  have  the  strongest  lungs;  that  is,  who  can  give  to  the 
chest  the  greatest  degree  of  permanent  dilatation.  In  contend- 
ing for  the  prize  in  running,  you  may  see  them  throw  back  their 
head  and  shoulders,  not  only  to  obviate  the  propensity  which 
there  is  in  the  line  of  the  centre  of  gravity  to  fall  towards  the 
anterior  plane,  but,  likewise,  that  the  cervical  column,  the  sca- 
pulae, the  clavicles,  and  the  humerus,  being  fixed,  may  furnish  .a 
firm  attachment  to  the  auxiliary  muscles  of  respiration. 

We  should  run  with  much  less  speed,  if  we  applied  to  the 
ground  the  whole  sole  of  the  foot;  partly  from  the  time  which 
would  be  taken  up  in  thus  applying  the  foot  to  the  ground,  and 
partly  by  the  friction  which  would  necessarily  take  place.  Hence, 
in  running  we  generally  touch  the  ground  only  with  the  end  of 
the  foot.  We  run  with  most  speed  when  the  foot  is  in  a state  of 
extension,  the  leg  being  moved  rapidly  by  the  extensors  of  the 
knee.  This  accounts  for  the  tendency  which  there  is  to  fall 
w’hile  we  run,  the  centre  of  gravity  obeving  impulses  which  fol- 
low each  other  in  rapid  succession,  and  never  resting  but  on  a 
basis  of  every  limited  extent.  Another  reason  why  the  slightest 
unevenness  of  the  ground  is  apt  to  occasion  falls  in  running  is, 
that  the  rapid  motion  communicated  to  the  body  by  the  sudden 
and  perpetually  recurring  extensions  of  the  posterior  extremity, 
increases,  at  every  step,  so  that  it  is  impossible  to  stop  sudden- 
ly, and  without  having  previously  slackened  one’s  pace,  and 
moderated  the  impulse  to  which  the  body  is  subjected. 

As  it  is  mostly  forward  that  falls  are  apt  to  take  place,  in 
running  we  always  throw  back  the  head,  and  make  use  of  our 
arms  to  balance  the  body',  so  that  they  may  be  in  constant  oppo- 
sition to  the  legs;  that  is,  that  the  right  lower  extremity,  for 

8 P 


482 


ON  MOTION. 


example,  being  carried  forward,  the  left  arm  may  be  balanced 
backward. 

Few  animals  are  better  formed  than  man  to  run  with  speed; 
his  lower  limbs  are  in  length  equal  to  one  half  of  the  whole 
length  of  the  body,  and  the  muscles  which  move  them  are  very- 
powerful;  hence,  savages,  who  are  in  the  constant  habit  of  run- 
ning, overtake  the  animals  which  they  make  their  prey;  and,- 
even  in  Europe,  there  are  professed  runners,  who  equal  in 
swiftness  the  fleetest  horse.  This  animal,  like  every  other  swift 
quadruped,  would  move  much  more  slowly  than  man,  on  ac- 
count of  the  number  of  the  limbs  on  which  he  rests,  if  he  had 
not  the  power  of  moving  them  in  pairs,  and  thus  reducing  his 
legs  to  two,  as  in  what  is  called  full  gallop. 

CLXXXVIII.  Of  leaping.  Leaping,  in  man,  is  performed, 
principally,  by  the  sudden  extension  of  the  lower  limbs,  whose 
articulations  were  in  a previous  state  of  flexion.  The  alternate 
angles  of  the  foot,  of  the  knee  and  hip,  disappear,  and  the  exten- 
sors contract  in  almost  a convulsive  manner.  This  straighten- 
ing is  not  limited  to  the  lower  limbs,  in  violent  leaping;  it  like- 
wise affects  the  vertebral  column,  which  acts  as  a bow  in 
unbending.  Professor  Barthez,  who  has  the  merit  of  having 
suggested  this  explanation,  which  Borelli  and  Mayow  had  very 
imperfectly  understood,  perhaps  goes  too  far,  in  considering  as 
imaginary,  a power  of  repulsion  in  the  ground.  This  re-action, 
admitted  by  Hamberger  and  by  Haller,  clearly  operates  when 
we  leap  on  an  elastic  floor;  it  enables  tumblers  to  rise,  without 
much  effort,  on  the  rope  which  bears  them.  But  though  all  phy- 
siologists do  not  admit  that,  in  leaping,  there  is  a re-action  from 
the  ground,  it  is  universally  admitted,  that  there  must  be  a cer- 
tain resistance  from  the  ground  on  which  we  tread.  In  fact,  a 
moving  sand,  yielding  to  the  pressure  of  the  body,  would,  by 
giving  W’ay  to  a considerable  degree,  render  it  impossible  to 
leap.  The  instantaneous  contraction  of  the  extensor  muscles  is 
so  powerful,  in  extending  the  lower  extremities,  and  in  com- 
municating to  the  body  a power  of  projection,  so  as  to  raise  it, 
that  frequently,  during  this  effort,  the  tendons  of  these  muscles, 
or  even  the  bones  into  which  they  are  inserted,  break  across.  It 
is  on  this  account,  that  dancers  are  very  apt  to  fracture  their 
patella.  This  accident  happens  at  the  moment  w'hen  their  bod}*, 


ON  MOTION. 


483 


in  rising  from  the  ground,  is  powerfully  elevated  to  a certain 
height. 

If  leaping  consists  merely  in  the  sudden  straightening  of  the 
lower  extremities,  whose  articulations  afe  bent  in  alternate  di- 
rections, it  must  be  more  considerable,  according  as  these  are 
longer,  more  bent  on  one  another,  and  as  the  muscles  which 
straighten  them  contract  more  powerfully.  Hence,  animals  that 
move  by  leaps,  as  the  hare,  the  squirrel,  and  the  jerboa,  have  pos- 
terior extremities  of  considerable  length,  in  proportion  to  their 
fore  legs.  Their  different  parts  are,  besides,  capable  of  conside- 
rable flexion.  All  these  animals,  strictly  speaking,  are  incapable 
of  walking  or  running;  and  they  move  by  leaps,  or  bounds,  suc- 
ceeding each  other  with  different  degrees  of  rapidity.  Some, 
however,  as  the  rabbit  and  the  hare,  are  capable  of  running  when 
climbing  up  a steep  place,  as  the  slope,  in  this  case,  lessens  the 
effect  of  the  impulse  communicated  by  the  extension  of  the  pos- 
terior limbs;  an  impulse  which,  from  the  strength  and  length  of 
these  extremities,  throws  the  whole  weight  of  the  body  on  the 
fore  legs,  which  are  weaker  and  shorter,  with  such  a degree  of 
force,  that  the  animal  is  obliged  to  stiffen  these,  and  to  keep  them 
straightened,  and  in  a state  of  extension,  to  avoid  striking  the 
ground  with  his  head,  while  leaping  on  an  horizontal  plane. 
Frogs,  but  especially  grasshoppers  and  fleas,  between  whose  hind 
extremities  and  the  rest  of  the  body  there  is  the  greatest  dis- 
proportion, astonish  us  by  the  very  considerable  space  which 
they  can  clear  at  a leap;  but  the  wonder  ceases,  when  we  consi- 
der that  powers  communicate  to  the  masses  equal  degrees  of 
velocity,  when  proportionate  to  one  another;  now,  the  space  gone 
over,  depending  entirely  on  the  velocity,  since  the  body  that 
leaps,  loses,  by  a gradation  which  nothing  can  lessen,  that  which 
it  had  acquired,  these  motions  must  be  nearly  alike  in  small  and 
in  large  animals. 

Swammerdam  says,  that  the  height  to  which  grasshoppers 
rise,  in  leaping,  is.  to  the  length  of  their  body  as  200  to  1.  A 
flea  leaps  still  farther  and  more  swiftly.'^ 

* Bartliez  states,  in  his  work  on  mechanics,  that  the  Arabs  call  this  little  in- 
sect the  father  of  leaping;  and  that  Roberval,  a natural  philosopher  of  conside- 
rable merit,  had  written  a work  entitled  de  saltu  pulicis.  Such  a subject,  thought 
by  the  ignorant  to  supply  matter  only  for  idle  and  fruitless  speculation,  may 
furnish  results  highly  interesting,  when  treated  by  an  able  man.  In  tenui  labor. 


ON  MOTION. 


484 

The  larva,  called  the  cheese  maggot,  forms  itself  into  a circle, 
by  contracting,  as  much  as  possible,  its  abdominal  muscular 
fibres;  after  having,  in  this  manner,  brought  near  to  each  other 
its  head  and  tail,  it  suddenly  extends  and  straightens  itself,  and 
sends  itself  to  a considerable  distance.  It  is  by  a similar  me- 
chanism, that  the  salmon,  the  trout,  and  other  fishes,  swim 
against  rapid  currents  interrupted  by  water-falls.  They  bend 
their  body,  to  a considerable  degree,  straighten  it  powerfully, 
and  thus  overcome  the  obstacle  which  opposes  their  progress. 
I believe,  however,  that  in  this  particular  case,  the  leap  is  not 
effected  solely  by  the  straightening  of  the  elastic  curve,  as  is 
maintained  by  some  authors,  but  that  it  is  likewise  occasioned 
by  the  resistance  against  the  water,  of  the  tail  of  the  fish,  which 
strikes  it  powerfully,  at  the  moment  of  raising  itself;  in  the  same 
manner,  as  in  the  northern  seas,  the  enormous  whale  strikes, 
with  so  sudden  and  violent  a blow  of  her  tail  against  the  water, 
as  to  receive  from  it  a fixed  point,  and  rise  to  the  height  of 
fifteen  or  twenty  feet,  as  we  are  informed  by  navigators.  Lob- 
sters leap  by  violently  extending  their  tail,  an  elastic  and  con- 
tractile arch,  which  they  had  previously  kept  bent  under  their 
body. 

This  theory  of  leaping  would  seem  to  be  contradicted  by 
what  is  related  by  Professor  Dumas,  of  a man  without  thighs, 
and  who,  nevertheless,  performed  surprising  feats  of  dexterity 
and  agility.  But  in  this  instance,  might  not  the  pelvis,  the  ver- 
tebral column,  and  especially  the  lumbar  portion  of  the  latter, 
make  up,  by  a greater  mobility,  for  the  w'ant  the  longest  of 
the  three  levers  formed  by  the  lower  extremity. 

In  the  act  of  leaping,  the  bodj , which  has  received  the  im- 
pulse, may  rise  in  one  of  two  ways,  perpendicularly  to  the 
horizon,  which  constitutes  the  vertical  leap,  or  in  a direction 
more  or  less  oblique.  The  vertical  leap  is  always  of  less  extent 
than  that  which  takes  place  in  an  inclined  direction,  and  the 
latter  is  always  greater  when  it  has  been  preceded  by  running. 
In  running  before  lea’ping,  we  have  already  acquired  an  impulse 
which  is  added  to  that  which  the  mechanism  of  leaping  may 
produce. 

To  convince  ourselves  of  the  reality  of  this  additional  power, 
let  us  recollect  how  difficult  it  is  to  stop  suddenly,  in  the  midst 


ON  MOTION. 


485 

of  a race,  if  we  have  not  previously  slackened  our  pace,  This 
impulse  is  one  of  the  causes  which  make  runners  fall  forward, 
when  the  lightest  obstacle  meets  their  feet;  but  whatever  may 
be  the  force,  the  direction  of  leaping,  and  the  powers  which 
produce  it,  the  body  by  which  it  is  executed  must  be  considered 
as  a real  projectile  that  is  impelled  by  a motion  counteracted 
by  the  force  of  gravitation.  Whatever  motions  we  may  perform, 
every  thing  depends  on  the  first  impulse;  as  soon  as  the  feet 
cease  to  be  in  contact  with  the  plane  which  supports  them,  it  is 
no  longer  in  our  power  to  atsgment  the  force  of  the  leap  or  its 
swiftness.  In  dancing  it  is  impossible  to  excel  in  cutting  capers, 
unless  one  is  capable  of  rising  to  a certain  height;  I have  uni- 
formly observed,  that  in  the  most  celebrated  public  dancers,  the 
trunk,  and  especially  the  lower  limbs,  are  very  muscular,  the 
calf  of  the  legs,  the  buttocks,  and  the  back  indicate,  by  their  bulk, 
a remarkable  degree  of  energy  in  the  entensors,  by  whose  ac- 
tion leaping  is  chiefly  effected. 

A dancer  w ho  rises  vertically,  falls  back  to  the  ground,  when 
the  force  of  gravitation  exceeds  the  impulse  which  he  had  re- 
ceived; his  fall  resembles  that  of  a projectile  in  vertical  motion; 
it  takes  place  according  to  a descending  line  that  is  perfectly 
similar,  in  direction  and  height,  to  the  ascending  line. 

The  same  thing  takes  place  in  the  oblique  leap,  except  how- 
ever, that  the  body,  like  a shell  projected  by  the  explosion  of  gun- 
powder, describes  a parabolic  curve,  ascending,  as  long  as  the 
impelling  power  exceeds  the  force  of  gravitation;  descending, 
when  the  latter,  which  increases  during  the  progress  of  the  leap, 
is  equal  to  the  force  of  impulse.  This  takes  place  when  the  body 
has  described  a curve  which  represents  the  half  of  a parobola; 
from  that  moment,  the  force  of  gravitation  goes  on  increasing, 
and  the  body  descends  in  a curve  corresponding  to  the  first.* 

CLXXXIX.  Of  swimming.  Few  animals  have  more  diflBculty 
than  man,  in  supporting  themselves  on  the  surface  of  a fluid;  yet 
the  weight  of  the  human  body  exceeds  but  little  that  of  the  same 
bulk  of  water;  sometimes  even  when  the  body  is  loaded  with 
much  fat,  its  specific  gravity  and  that  of  water  are  the  same. 
Hence  it  is  observed,  that  corpulent  men  swim  with  less  effort; 

* In  saitu  ad  horizontem  obliquo,  tnotus  fit  per  lineatn  parabolicam  proxime, 
Borelli.  op.  cit.  prop.  irS. — Vide  Galileo  on  the  motion  of  projectiles. 


ON  MOTION. 


486 

but  the  weight  is  not  equally  distributed  over  every  point  of  the 
supporting  fluid.  The  head,  whose  relative  weight  is  very  consi- 
derable, is  the  principal  difficulty  in  swimming,  and  it  requires 
some  effort  to  keep  it  raised,  so  as  to  allow  the  air  to  enter  freely 
into  the  lungs,  through  the  mouth  and  nostrils.  The  upper  and 
lower  limbs  act  alternately  against  the  water  which  they  dis- 
place by  pressing  on  it.  In  these  various  motions,  there  is  a 
successive  flexion,  extension,  abduction,  and  adduction  of  the 
limbs;  most  of  the  muscles  of  the  body  are  in  motion,  and 
have  their  fixed  point  of  action  in  the  chest,  which  swimmers 
keep  expanded  by  retaining,  by  a constriction  of  the  glottis,  a 
considerable  quantity  of  air  within  the  pulmonary  tissue.  This 
continuous  dilatation  of  the  chest  is  attended  with  this  further 
advantage,  that  it  renders  the  body  specifically  lighter.  The 
force  with  which  the  swimmer  is  obliged  to  strike  the  water, 
the  rapidity  with  which  the  motions  must  succeed  each  other, 
that  the  fluid  may  yield  him  a sufficiently  fixed  point  of  action, 
accounts  for  the  fatigue  with  which  this  exertion  is  attended. 

Fishes  are  adapted,  by  their  structure,  to  the  element  in 
which  they  live;  the  form  of  their  body  bounded,  every  where, 
by  salient  angles,  is  well  calculated  to  separate  the  columns  of 
a fluid.  A bladder  filled  with  azote,  which  is  expelled  at  plea- 
sure, renders  the  specific  gravity  less  than  that  of  water,  accord- 
ing to  the  quantity  of  gas  it  contains;  lastly,  their  tail,  moved 
by  powerful  muscles,  may  be  considered  as  an  oar  of  great 
strength,  the  motions  of  which  impel  the  fish  forward,  while 
the  fins,  like  so  many  secondary  oars,  facilitate  and  direct  his 
motions. 

The  air  bladder  of  fishes  gives  to  their  back  a sufficient 
degree  of  lightness  to  enable  it  to  remain  upward,  else  this  part 
of  the  body,  which  is  the  heaviest,  would  draw  after  it  the  rest, 
and  the  animal,  lying  on  his  back,  would  be  incapable  of  per- 
forming any  motions  of  progression;  this  happens  when  this 
bladder  is  burst  or  punctured.  Constrictor  muscles  expel  the 
gas  which  it  contains,  and  force  it  into  the  stomach,  or  (esopha- 
gus, when  the  animal  wishes  to  sink.  This  expulsion  becomes 
impracticable,  if  the  gas  undergoes  considerable  expansion, 
from  the  application  of  heat,  and  resists  the  compression  that 
is  applied  to  it.  Hence,  during  the  fry-time,  fishes,  after  re* 


ON  MOTION.  43  y 

maining  long  on  the  surface  of  the  water,  exposed  to  the  heat 
of  the  sun,  become  unable  to  sink,  and  are  easily  caught. 

As  the  fish  is  entirely  surrounded  by  a medium  which  pre- 
sents, on  every  side,  an  equal  resistance^  the  velocity  which  he 
might  have  acquired,  by  striking  the  fluid  behind  with  his  tail, 
would  be  lost,  from  the  resistance  of  the  water  which  he  would 
have  to  displace  forward,  if,  immediately  after  striking  with  his 
tail,  he  did  not  bring  it  back  into  a straight  line,  so  as  to  pre- 
sent to  the  fluid,  only  the  inconsiderable  breadth  of  his  body; 
the  velocity  with  which  he  moves  is,  besides,  very  inferior  to 
that  with  which  he  uses  his  tail.  This  part  being  brought  into 
a straight  line,  the  fish  contracts  it  to  its  smallest  dimensions, 
at  the  sanie  time  that  he  brings  it  to  the  other  side;  he  then 
expands  it  and  strikes  the  fluid,  in  a contrary  direction,  in  a line 
between  the  two  oblique  impulses  which  both  strokes  have 
given  to  it.  The  fish  turns  horizontally,  and  directs  himself 
towards  the  side  he  chooses,  by  striking  more  powerfully,  or 
with  greater  quickness,  on  one  side  than  on  the  other,  or  by 
striking  only  on  one  side. 

Fishes  without  an  air  bladder,  are  reduced  to  live  at  the  bot- 
tom of  the  water,  unless  they  have  a flat  body  and  are  furnished 
with  horizontal  fins,  so  as  to  enable  them  to  strike  a consider- 
able surface  of  water,  in  a powerful  manner,  as  is  the  case  with 
rays,  whose  wide  fins  are  not  inaptly  termed  wings;  the  motion 
of  these  fishes,  in  the  water,  precisely  resembling  that  of  birds 
in  the  air,  with  no  other  difference  but  that  of  the  different 
density  of  the  medium  in  which  they  move,  as  will  be  shown 
in  treating  of  the  motions  of  progression  peculiar  to  this  class 
of  animals. 

CXC.  Of  fifing.  A bird,  in  rising,  or  in  moving  in  the  air, 
has  to  use  much  more  force  and  with  much  greater  velocity, 
than  a fish  in  swimming.  He  has  not  the  power,  like  the  latter, 
of  placing  himself  in  equilibrio  with  the  fluid  in  which  he  moves, 
by  means  of  an  internal  organ  that  renders  his  specific  gravity- 
equal  to  that  of  the  medium  he  is  in.  This  medium,  besides, 
presents  less  resistance  to  the  powers  which  strike  it  to  obtain  a 
point  of  support. 

Though  birds  are  incapable  of  becoming  as  light  as  the  air,  it 
is,  however,  in  their  power  to  obtain  a specific  gravity,  not  much 


ON  MOTION. 


488 

exceeding  that  of  the  atmosphere.  Nature  has  rendered  thenfi 
very  light,  by  providing  them  with  very  capacious  lungs,  capable 
of  great  dilatation,  from  the  remarkable  mobility  of  the  par'^tes 
of  the  chest,  and  by  extend  ng  the  lungs  into  the  abdomen,  by 
means  of  membranous  sacs,  and  into  the  skeleton,  by  means  uf 
canals  which  establish  a communication  of  these  abdominal  and 
osseous  aerial  tubes  with  the  pulmonary  organ;  so  that  the 
whole  body,  distended  by  air  rarefied  bv  a considerable  dejjree 
of  heat,  since  it  is  ten  degrees  above  that  of  other  warm  bl mded 
animals,  clothed  in  feathers  almost  as  light  as  the  air  itself,  re- 
quires but  a moderate  degree  of  force  to  support  itself  in  that 
medium.  On  the  other  hand,  when  the  wings  are  expanded, 
they  present  to  the  fluid  a very  extensive  surface;  the  pectoral 
muscles  which  set  them  in  m'  tion,  are  besides,  sufficiently 
strong  to  strike  the  air  with  a power,  and  to  repeat  the  stroke 
with  a rapidity  and  continuousness  of  which  no  other  animal 
would  be  capable.  We  know  how  powerful*  the  muscles  of  tha 
wings  are,  even  in  th»j  tame  fowl,  which  make  so  very  little 
use  of  them.  Lastly, .the  contractility  of  these  very  powertul 
muscles,  is  greater  in  birds  than  in  any  other  animal;  no  one 
possesses  so  much  strength  in  so  small  a compass.  What  quad- 
ruped of  the  same  weight  as  an  eagle,  could  strike  with  his  foot 
so  violent  a blow  as  that  bird,  when  to  stun  his  prey  or  to  de- 
fend himself,  he  gives  repeated  blows  with  his  pinion?  This 
muscular  energy  is,  no  doubt,  connected  with  the  extensive 
respiratory  organs,  with  the  highly  stimulating  qualities  of  a 
blood  that  is  warmer,  more  oxydized,  more  concrescible,  in  a 
word,  more  arterialized  than  that  of  any  other  animal. 

Let  us  now  inquire  how  birds,  endowed  with  an  organization 
so  favourable  to  flying,  perform  that  action.  A bird  begins  by 
ascending  into  the  air,  either  by  rising  at  once  from  the  ground, 

* Birds  have  three  pectoral  muscles;  the  great  pectoral  which  is  attached  to 
their  enormous  sternum,  and  alone  exceeds  in  weig'lit  all  the  other  muscles  of 
the  bird  together;  the  rtiiddle pectoral,  whose  tendon  turns  over  a kind  of  pulley, 
and  is  attached  to  the  head  of  the  liumerus  which  it  raises:  bj’  means  of  li.is 
mechanism,  nature  has  placed  an  elevator  muscle  at  the  lower  part  of  the  body, 
so  as  to  iucyease  the  weight  of  tliis  part  of  the  bird,  which,  without  this  kind 
of  ballast,  might  have  been  upset  in  the  air.  The  third,  or  lesser  pectoral,  iS 
destined  to  draw  the  humerus  towards  the  body. 


ON  MOTION. 


489 

or  by  allowing  himself  to  fall  from  a height.  If  on  the  ground, 
and  if  his  wings  are  too  large  to  be  freely  spread,  he  has  a 
difficulty  in  rising;  in  that  case  he  goes  to  an  elevated  spot  and 
throws  himself  from  it,  that  he  may  have  sufficient  room  to  ex- 
tend his  wings  and  strike  in  the  air,  the  first  stroke  that  is  to 
raise  him.  The  wings  expand  horizontally,  the  humerus  which 
forms  their  principal  part,  standing  off  from  the  body;  they  then 
descend  rapidly,  and,  as  the  air  resists  the  sudden  effort  which 
tend  to  depress  it,  the  body  of  the  bird  is  elevated  by  a kind  of 
clastic  re-action,  corresponding  to  the  leap  of  man  and  to  the 
swimming  of  fishes;  the  impulse  being  given,  the  bird  closes  his 
wings,  contracts  his  dimensions,  as  much  as  possible,  that  the 
impulse  may  be  almost  entirely  employed  in  raising  his  body, 
and  may  not  be  counteracted  by  the  resistance  of  the  air.  This 
resistance  of  the  air,  but  particularly  the  weight  of  the  bird, 
would  soon  overcome  the  velocity  that  has  been  obtained,  and 
he  would  drop,  if,  by  again  striking  the  air,  he  did  not  again 
rise.  If  the  bird  strikes  a second  time  with  his  wings  before  the 
impulse  communicated  by  the  first  stroke  is  over,  he  rises  ra- 
pidly, but,  on  the  contrary,  descends,  if  this  motion  is  delayed. 
If  he  allow  himself  to  fall  only  to  the  height  whence  he  began 
to  rise,  he  may,  by  a continuance  of  equal  vibrations,  keep  at 
the  same  height.  A bird,  sometimes,  ceases  altogether  to  move 
his  wings,  closes  them  against  his  sides  and  falls,  with  a pre- 
cipitate motion,  like  any  other  weighty  body.  The  name  of 
pouncing  is  given  to  the  rapid  descent  of  predaceous  birds  on 
their  prey.  Observe  a falcon  drop  suddenly  on  a poultry  yard; 
if  on  the  point  of  reaching  the  ground,  he  perceive  danger,  he 
immediately  spreads  his  wings,  and  thus  saves  himself  from  fall- 
ing; for,  whatever  velocity  he  may  have  acquired  in  this  rapid 
motion,  the  resistance  of  the  air  always  increases,  as  the  squares 
of  the  velocity;  he  then  rises  anew  and  takes  to  flight.  This 
peculiar  act  is  called  resource. 

The  oblique  motions  differ  from  the  vertical  motion  which 
has  just  been  described,  in  this,  that  the  bird  rises  by  a series  of 
curves  which  are  more  or  less  extended,  as  the  motion  is  more 
horizontal  or  vertical.  In  consequence  of  the  peculiar  strength 
of  their  wings,  birds  of  prey  have  a very  powerful  horizontal 

3Q 


( 


ON  MOTTON. 


490 

motion,  so  that  in  soaring,  the  curves  which  they  describe  are 
so  slight,  that  the  motion  seems  quite  horizontal. 

Swimming,  to  many  birds,  is  a more  natural  mode  of  pro- 
gression than  flying;  these  birds  are  very  light,  their  body  is 
covered  with  a light  down,  and  with  feathers  over  which  the 
water  glides  very  readilv;  their  bodv  is  flattened,  and  rests  on 
the  fluid  by  a broad  surface.  I heir  pelvis  is  shaped  like  the  keel 
of  a ship;  lastly,  their  toes  united  bv  webs,  strike  the  water  with 
a very  broad  surface.  This  is  the  case  with  the  numerous  tribes 
of  web-footed  or  water-fowl. 

They  who  have  conceived  it  to  be  possible  for  man  to  support 
himself  in  the  air,  by  rendering  his  body  specifically  lighter,  have 
not  considered,  that  it  was  impossible  to  give  to  the  muscles 
which  move  the  arms  a sufficient  degree  of  strength,  to  enable 
Ihem  to  move  the  machines  which  are  adapted  to  them;  and  all 
who  have  ventured  to  try  such  machines,  have  suffered  for  their 
rashness. 

CXCI.  Of  crawling.  All  the  motions  of  progression,  of  which 
man  and  animals  are  capable,  may  be  referred  to  the  theory  of 
the  lever  of  the  third  kind.  The  body,  in  leaping,  as  in  walk- 
ing, may  be  compared  to  an  elastic  curve,  since  the  point  of 
support,  or  fulcrum,  is  in  the  ground;  the  force,  the  spring  or 
power,  in  the  extensor  muscles,  and  the  resistance  in  the  weight 
of  the  body.  What  is  running,  but  a succession  of  short  leaps, 
and  is  not  its  mechanism  intermediate  between  walking  and 
leaping?  Are  not  flying  and  swimnung  real  leaps,  in  which  the 
body  of  the  animal  alternately  bends  and  unbends,  having  its 
support  on  media  of  much  less  resistance  than  the  ground,  on 
which  walking,  running,  and  leaping  are  generally  performed? 
The  mode  of  progression  peculiar  to  serpents  and  soft  reptiles, 
furnishes  an  additional  application  of  the  lever  of  the  theorv  of 
the  third  kind.  The  snake,  which  moves  by  forming  with  its 
body  horizontal  and  vertical  undulations,  forms,  in  the  course 
of  its  length,  a series  of  curves  and  straight  lines,  in  succession, 
from  the  head  towards  the  tail;  but  sometimes,  likewise,  from 
the  tail  towards  the  head,  in  the  serpents  called  amphisbcenous^ 
in  which  the  scales  covering  the  belly  are  equally  favourable  to 
a retrograde  motion,  as  to  a motion  forw^ard. 

The  crawling  of  serpents  is  facilitated  by  the  length  of  their 


OjS"  motion. 


491 


body,  by  the  smoothness  of  their  scales,  the  immense  power  of 
their  muscles,  and  the  flexibility  of  their  vertebral  column.  The 
bones  which  form  this  part  of  the  skeleton,  are  articulated  by 
arthrodia,  and  loosely  jointed,  so  that  a very  slight  cause  de- 
stroys their  union;  hence,  a blow  with  a very  small  stick  is  ca- 
pable of  killing  the  largest  serpents,  if  applied  on  the  back.  The 
lateral  inflexions  of  this  column  are  very  considerable;  the 
degree  of  extension  is  limited  by  the  spinous  processes,  and 
these  are,  sometimes,  of  considerable  size,  as  in  the  rattle 
snake.  Hence,  notwithstanding  what  has  been  stated  by  several 
authors,  and  although  painters  have  represented  serpents 
moving  in  vertical  curves,  they  move,  in  most  instances,  in 
horizontal  curves. 

A serpent,  to  swim,  is  obliged  to  bend  and  unbend  his  body 
in  more  rapid  succession;  this  swimming  consists  merely  in 
crawling  faster,  and  in  moving  on  a less  resisting  plane. 

The  motions  of  reptiles,  in  swimming,  surpass,  in  strength 
and  velocity,  those  of  reptiles  which  crawl  on  the  ground,  in  as 
much  as  the  latter  yields  a more  fixed  point  than  water.  If  the 
serpent  is  desirous  of  leaping,  he  suddenly,  and  at  once,  brings 
to  a straight  line  all  his  curves,  resting,  at  the  same  time,  on  the 
extremi  y of  that  which  is  nearest  his  tail;  then,  as  I have 
several  times  observed,  he  describes  the  smallest  possible  num- 
ber of  curves,  bends  into  three  or  four  greater  arches  than  usual, 
but  never  into  a single  one,  whatever  the  length  of  his  body 
may  be. 

Tortoises,  frogs,  lizards,  salamanders,  and  all  reptiles  that 
have  legs,  drag  themselves  along  on  their  belly,  being  ill  sup- 
ported by  their  weak  limbs,  which  bear  no  proportion  to  the 
bulk  of  their  body,  and  can  scarcely  be  said  to  crawl  by  a 
mechanism  sim\lar  to  that  which  has  just  been  explained. 

Caterpillars  and  maggots  crawl  much  in  the  same  manner  as 
serpents.  The  legs  of  the  caterpillar,  too  feeble  to  support  it, 
or,  of  themselves,  to  carry  the  body  forward,  are  used  by  these 
creatures  to  obtain  a hold  on  the  surface  on  which  they  move, 
by  bending,  in  arches,  mostly  vertical,  the  parts  situated  be- 
tween the  legs,  that  are  in  pairs,  at  a certain  distance  from  one 
another.  The  caterpillars  that  have  a scaly  covering,  craw! 
better,  the  elasticity  of  their  scales  assisting  the  contractile 


492 


ON  MOTION. 


action  of  their  muscular  fibres.  Earth  worms  move,  at  times,  in 
undulations,  as  the  snake,  and  at  others,  by  dragging  themselves 
like  slugs.  This  last  variety  of  crawling  is  performed  as  follows: 
instead  of  forming  distinct  curves,  the  contractile  fibres  of  the 
reptile  shorten  themselves  from  the  head,  which  is  fixed,  towards 
the  tail  which  is  moveable,  and  the  animal  performs  only  slight 
inflexions.  We  may  compare  the  mode  of  crawling  peculiar  to 
some  animals,  to  the  motion  by  which  a man  lying  horizontally, 
on  his  belly,  moves  forward,  by  drawing  his  whole  body  to- 
wards his  arms,  w'hich  are  in  a state  of  extension,  and  with 
which  he  has  a hold  of  some  fixed  object.  The  motion  of  the 
snail  is  performed  almost  entirely  in  the  same  manner. 

The  snail,  loaded  with  his  shell,  adheres  to  the  surface  oa 
which  he  moves,  by  a viscid  and  glutinous  fluid,  which  coagu- 
lates, and  forms  on  his  track  a shining  varnish.  This  creature 
fixes  itself,  likewise,  on  the  ground,  by  forming  a vacuum  with 
a part  of  its  body  on  which  it  crawls,  which  is  broad,  fringed, 
and  well  adapted  to  answer  the  purpose  of  a cupping  glass.  It 
is  by  this  double  resource  of  a viscid  and  glutinous  fluid,  and 
of  a contractile  exhauster,  that  the  snail  fixes  the  fore  part  of 
his  body,  and  then  draws  towards  this  fixed  part,  the  rest  of  his 
body  loaded  with  the  shell.  This  part  of  the  snail,  by  which  it 
fastens  itself  to  the  ground  on  which  it  crawls,  bear  some 
analogy  to  the  tentacula  which  assist  the  progression  of  the 
sepia  and  other  cephalopodous  molusca. 

CXCII.  Partial  tnotions  performed  by  the  upper  extremities. 
These  motions  will  furnish  us  additional  illustrations  of  the 
elastic  curve,  or  of  the  third  lever,  to  the  theory  of  which  may 
be  referred  almost  all  the  motions  of  man  and  of  the  lower  ani- 
mals. This  idea  simplifies  and  facilitates,  in  a remarkable  man- 
ner, the  study  of  animal  mechanics;  it  may  be  considered  as  a 
general  formula,  by  the  help  of  which  we  may  obtain  a solution 
of  all  the  problems  of  this  interesting  part  of  physical  science. 
Its  application  particularly  distinguishes  what  has  just  been 
stated  on  motion,  from  what  had  been,  heretofore,  written  on 
the  same  subject. 

The  upper  extremities,  in  man,  are  not  employed  in  motions 
of  progression,  at  least,  not  generally,  except  in  a few  instances, 
as,  for  example,  when  the  limbs  being  extended  and  the  hands 


ON  MOTION. 


493 

having  a firm  hold  of  a body,  the  action  of  the  great  pectorals 
draws  the  whole  body,  lying  prone  on  a horizontal  surface,  or 
suspended. 

We  experience  a difficulty  in  climbing,  because  our  hands 
alone  enable  us  to  grasp  the  body  on  which  this  mode  of  pro- 
gression is  to  be  effected,  while  the  four  extremities  of  the 
quadrumana  and  the  sharp  claws  of  cats,  those  of  climbing 
birds,  render  this  action  easy  and  natural  to  all  these  animals. 

There  exists  so  great  a disproportion,  in  point  of  length  and 
strength,  between  our  upper  and  lower  extremities,  that  walk- 
ing on  all  fours  can  never  be  natural  to  the  human  species;  be- 
sides, as  Daubenton  observed,  the  situation  of  the  foramen 
magnum  of  the  occipital  bone,  in  man,  renders  this  attitude 
exceedingly  uneasy.  Its  situation,  near  the  centre  of  the  base 
of  the  skull,  and  nearly  horizontal,  prevents  the  head  from  being 
raised  sufficiently  high  to  enable  us  to  turn  our  face  forward  and 
to  see  before  us,  and  if  we  bring  the  head  downward,  it  strikes 
the  ground  with  its  summit,  or  with  the  forehead.*  But  our 
upper  or  thoracic  limbs,  though  of  no  use  in  conveying  us 
whither  our  wants  require,  are  almost  exclusively  destined  to 
perform  motions  by  which  we  act  on  the  object  towards  which 
vve  have  brought  ourselves. 

If  we  wish  to  push,  or  draw  towards  us,  or  to  propel  afar  a 
moveable  body,  to  compress,  to  elevate,  or  to  lower  it,  our 
upper  extremities  are  almost  exclusively  engaged  in  this  office. 

In  pushings  man  places  himself  between  the  obstacle  and  the 
ground;  he  bends  his  body  between  these  two  points,  by  bring- 
ing all  his  limbs  into  a state  of  flexion;  he  then  extends  them: 
his  whole  body  represents  a spring  which  is  released  and  re- 
covers itself,  and  the  two  extremities  of  which,  meeting  two  ob- 
stacles, the  ground  and  the  body  to  which  the  impulse  is  to  be 
communicated,  exert  their  action  on  the  one  of  the  two  which 
is  the  more  easily  moved.  The  force  is  equal  to  the  contraction 
of  the  extensors,  which  elongate*  the  body  previously  in  a state 
of  decvtrtation,  and  advance  the  moveable  obstacle  by  the  whole 
difference,  in  regard  to  length,  of  a man  whose  limbs  are  in  a 
state  of  flexion,  and  of  the  same  man  while  these  parts  are  in  a 

• Dictionnaire  d’Histoii'e  Naturelle  de  I’Encyclopedie  methodique.  Intro- 
duction, page  21  et  suiv. 


ON  MOTION. 


494 

state  of  extension.  It  is  in  the  same  manner,  and  by  a similar 
mechanism,  that  by  pushing  against  the  shore  with  an  oar,  we 
force  a boat  from  it.  The  vertebral  column  represents  an  elastic 
curve  which  straightens  itself,  between  the  feet  which  rest 
against  the  bottom  of  the  boat  and  the  end  of  the  pole  or  oar, 
pushed  against  the  shore,  or  the  bottom  of  the  water. 

If,  on  the  contrary,  we  wish  to  draw  towards  us  a body,  we 
seize  it  with  extended  arms:  we  then  bend  them  forcinly;  the 
spring,  which  is  in  a state  of  tension,  shortens  itself:  the  effort  is 
wholly  performed  by  the  flexors;  it  is  less  fixed,  and  of  less  dura- 
tion than  that  of  the  extensors:  because  the  axes  of  the  bones  do 
not  correspond  to  one  another  in  a straight  line,  and  because  the 
action  is  generally  partial. 

We  can  throw,  to  a distance,  a projectile,  the  arm  remaining 
pendulous,  and  performing  a mere  oscillatory  motion,  or  by  a 
whirling  motion  of  the  arm.  This  last  action  is  much  more 
powerful,  because  the  muscles,  which  go  from  the  trunk  to  the 
upper  extremity,  concur  in  it.  In  the  former,  the  previous 
oscillations  gives  to  the  arm  a motion  that  is  peculiar  to  it,  which 
is  added  to  the  force  of  muscular  contraction,  and  which  aug- 
ments its  effects. 

Professor  Barthez  was  aware  that  the  motions,  by  which  the 
upper  extremity  stiffens  itself,  and  assumes  a state  of  extension 
to  project  a moveable  body,  or  to  repel  a resistance  that  is  op- 
posed to  it,  perfectly  resemble  leaping,  and  are  attended,  like 
that  action,  with  a sudden  extension  of  the  joints  which  were 
previously  bent.  In  motions  applied  to  a resistance  that  cannot 
be  overcome,  the  body  is  not  repelled  with  the  force  communi- 
cated to  it  in  leaping,  by  the  abrupt  extension  of  the  lower  ex- 
tremities. The  scapula  is  too  moveable  on  the  trunk,  its  articu- 
lation with  the  humerus  is  too  unsteady,  and  the  action  of  this 
bone  is  not  directed,  with  regard  to  the  shoulder,  in  a sufficiently 
favourable  manner,  to  render  the  impulse  equally  great,  even 
though  the  powers  should  be  equal:  and  they  are  far  from  being 
so.  In  every  repulsion,  and  in  every  attraction,  whether  w'e 
bring  towards  us  an  object  or  remove  it  from  us,  by  acting  upon 
it,  with  our  superior  extremities,  these  limbs  represent  an  elas- 
tic arch,  which  is  curved  or  straightened  by  the  action  of  its 
flexors  or  extensors;  and  these  motions,  like  the  greater  number 


ON  MOTION.  495 

of  those  which  we  have  hitherto  considered,  present  a precise 
application  of  the  levers  of  the  third  kind. 

The  action  of  seizing  a body,  with  the  hand,  is  facilitated, 
1st,  by  the  action  of  the  radius  on  the  ulna,  which  perforins  pro- 
nation and  supination,  motions  which  belong  exclusively  to  the 
hands,  and  of  which  the  feet  are  incapable;  2dly,  by  the  mobility 
of  the  wrist,  which,  properly  speaking,  is  capable  of  flexion 
and  extension  in  two  directions;  for,  the  extension  of  the  hand 
does  not  consist  in  merely  bringing  it  into  a parallel  line  with 
the  axis  of  the  limb,  but  it  is,  besides,  capable  of  turning  it 
round  towards  the  back  part  of  the  fore  arm:  a phenomenon  not 
observable  in  any  other  articulation;  3dly,  by  the  obscure  mo- 
tions, on  one  another,  of  the  bones  of  the  carpus,  by  which  the 
palm  of  the  hand  becomes  more  concave;  4thly,  by  the  motions 
of  opposition  and  circumduction  of  the  thumb  and  little  finger; 
5thly,  by  the  great  number  of  the  phalanges;  every  thing,  in 
this  part  of  the  upper  extremity,  proves  the  excellence  of  its 
structure,  and  justifies  all  that  philosophers  and  naturalists 
have  said  of  its  advantages. 

In  applying  pressure,  for  instance,  in  pressing  on  a seal, 
nearly  the  whole  weight  of  the  body  bears  on  one  of  the  upper 
extremities,  which  is  powerfully  extended,  the  shoulder  resting 
on  the  arm,  so  that  the  glenoid  cavity  of  the  scapula  may  be 
perpendicular  to  the  head  of  the  humerus. 

It  would  be  a superfluous  task,  to  endeavour  to  describe  all 
the  motions  which  our  parts  may  execute;  these  partial  motions 
are  explained  in  anatomical  works,  in  treating  of  the  muscles  on 
whose  action  they  depend.  I shall  content  myself  with  having 
inquired  into  the  principal  phenomena  of  animal  mechanism, 
chiefly  with  a reference  to  the  human  structure.  Fuller  details, 
on  animal  mechanism,  would  be  out  of  place,  in  a work  like  this. 
They  will  be  found  in  those  works  which  treat  professedly*  of 
this  important  part  of  physiology,  the  only  one  in  which  it  is 
possible  to  obtain,  in  the  investigation  of  its  objects,  that  degree 

* Consult  J A.  Borelli,  -de  motu  animalium,  4to,  The  errors  contained  in 
this  work  depend  on  the  circumstance  of  the  author’s  being-  more  of  a mathe- 
matician than  of  an  anatomist. 

P.  J . Barthez,  nouvelle  JHechanique  lies  mouvemens  de  C Humme  et  lies  animaux. 


ON  MOTION. 


496 

of  mathematical  certainty,  so  much  sought  after  by  every  man 
of  precision  and  of  sound  judgment. 

CXCIII.  Partial  motions  may  yet  further  be  studied  as  signs 
expressive  of  ideas.  They  compose  what  is  called  the  language 
of  action,  and  are  supplemental  to  speech.  The  language  of  ges- 
ture, in  its  perfection,  is  found  sufficient  even  to  express  the 
most  subtle  ideas,  and  the  finest  feelings,  in  the  mute  scenes 
known  under  the  name  of  pantomimes.  The  gestures,  with 
which  the  man  of  most  phlegm  accompanies  his  discourse,  are 
a language  sOperadded  to  that  which  he  speaks;  they  contribute 
to  the  exposition  of  the  thought;  but  what  force,  in  the  man  of 
passion,  do  they  not  add  to  his  expression!  what  power  to  his 
language!  This  eloquence  of  gesture,  w’hich  was  so  often  em- 
ployed to  move  and  sway  the  assembled  multitude  in  the  pub- 
lic place  of  Rome  and  Athens,  was  habitual  to  the  orators  of  the 

% 

ancient  republics;  and  the  moment  when  INIarc  Anton}’  uncovers 
and  shows  to  the  Roman  people,  the  bloody  corse  of  the  first  of 
the  Csesars,  is  not  the  least  eloquent  passage  of  his  harangue. 

Thus,  although  the  organ  of  voice  is  that  which  offers  us  the 
greatest  abundance  of  resources  for  the  expression  of  our  ideas, 
for  communication  with  our  fellow  creatures, — though  the  hear- 
ing be  the  sense  to  which  we  must  address  ourselves  to  produce 
in  them  distinct,  varied,  and  lasting  impressions, — we  do  yet 
address  ourselves  to  their  touch  and  their  sight,  when  we  would 
strongly  move  them,  by  an  energetic  declaration  of  our  desires. 
These  three  different  languages  arc  employed  at  once,  when 
we  lead  a man  towards  an  object,  and  at  the  same  time  point  it 
out  to  him,  and  bid  him  go  there:  touch  and  gesture  are  then 
auxiliary  to  speech,  and  testify  in  him  who  makes  use  of  them, 
a strong  and  resolute  will.  The  motions  of  the  eyes,  the  eye- 
brows, the  eye-lids,  the  lips,  and  generally,  of  all  the  parts  of 
the  face,  those  of  the  upper  limbs,  and  of  the  trunk  itself,  serve 
to  express  our  passions,  as  well  as  our  ideas,  are  supplemental 
to  the  language  of  convention,  and  often  betray  it,  by  saying  the 
reverse  of  what  it  expresses.  The  study  of  gestures,  of  motions, 
and  of  attitudes,  considered  as  signs  of  ideas  and  passions,  is 
the  department  of  metaphysicians,  of  painters,  of  sculptors,  and 
physiognomists.* 

♦ See  Condillac’s  Essay  on  the  Origin  of  Human  Knowledge;  Buffbn's  Na- 


497 


CHAPTER  IX. 

OF  VOICE  AND  SPEECH. 

CXCIV.  The  voice  is  an  appreciable  sound,  resulting  from 
the  vibrations  which  the  air,  expelled  from  the  lungs,  meets 
with,  in  passing  through  the  glottis.  From  this  sound,  articu- 
lated by  the  motions  of  the  tongue,  the  lips,  and  other  parts  of 
the  mouth,  is  produced  speech^  which  may  be  defined  articu- 
lated voice. 

All  animals  furnished  with  a pulmonary  organ  have  a voice; 
for  it  is  sufficient,  to  the  production  of  this  sound,  that  air,  col- 
lected in  any  receiver,  be  driven  out  in  a body,  with  a certain 
force,  and  that  it  meet,  on  its  passage,  with  elastic  and  vibratory 
parts.  Fish,  that  have  only  tracheae,  utter  no  sound:  but  this 
defect,  which  is  certainly  an  impediment  to  the  extent  and 
facility  of  their  relations,  is  in  part  made  up  by  the  extreme 
velocity  of  their  progressive  motion. 

The  instrument  of  voice  is  the  larynx,  a sort  of  cartilaginous 
box,  placed  at  the  upper  part  of  the  trachea.  The  thin  and 
elastic  cartilages  which  form  its  parietes  are  united  by  mem- 
branes, and  moved  on  one  another  by  many  little  muscles, 
called  laryngeal.  Of  these  five  cartilages,  three  only  are  con- 
cerned in  the  production  of  voice,  these  are  the  arytenoid  and 
the  thyroid.  The  epiglottis  is  of  no  other  use  than  to  close,  to 
what  we  swallow,  the  entrance  of  the  windpipe,  whilst  the  cri- 
coid, situated  at  the  lower  part  of  the  organ,  serves  it  for  a 
base,  on  which  the  arytenoid  and  the  thyroid  execute  the  mo- 
tions, by  which  the  opening  of  the  glottis  is  contracted  or  en- 
larged, for  the  formation  of  acute  or  grave  tones. 

This  slit,  from  ten  to  eleven  lines  long  in  an  adult,  and  from 
two  to  three  wide,  were  the  width  is  greatest,  is  the  most  es- 
sential part  of  the  larynx.  It  is  really  the  organ  of  voice,  which 
is  gone  at  once,  when,  by  opening  the  trachea,  or  the  larnyx 

tural  History  of  Man;  Winkelmann’s  Treatise  on  Art;  Lavater’s  Essay  on 
Physiognomy;  with  the  important  additions  by  M.  Moreau  (de  la  Sarthe^)  in 
the  edition  he  has  just  published. 

3 R 


OF  VOICE  AND  SPEECH. 


498 

below  It,  the  air  is  prevented  from  passing  through  it.  Speech 
only  is  lost,  when  the  wound  is  above  the  place  of  the  glottis} 
which  shows  that  voice  and  speech  are  two  distinct  phenomena, 
one  taking  place  In  the  larynx,  and  the  other  resulting  from  the 
action  of  divers  parts  of  the  mouth,  and  especially  the  lips. 

Are  the  different  modifications  of  which  the  voice  is  suscep- 
tible, dependet^t  on  the  width  or  straightness  of  the  glottis,  or 
on  the  tension  or  relaxation  of  the  ligaments  forming  its  sides? 
Must  we  believe,  with  Dodart,  that  the  larynx  is  a wind  instru- 
ment, or  with  Ferrein,  that  it  is  a stringed  instrument. 

It  is  very  true  that  the  voice  becomes  stronger,  fuller,  and 
passes  from  the  acute  to  the  grave,  as  the  glottis  enlarges  with 
the  progress  of  age; — that  it  remains  always  weaker  and  sharper 
in  a woman,  whose  glottis  is  nearly  a third  srnaller  than  a man’s; 
— but  the  tension  or  relaxation  of  the  ligaments  which  form  the 
sides  of  the  glottis,  (the  vocal  strings  of  Ferrein)  may  they  not 
enable  these  ligaments  to  execute,  in  a given  time,  vibrations 
more  or  less  prolonged,  and  more  or  less  rapid,  in  such  a man- 
ner, that  if  the  air  expelled  from  the  lungs  by  expiration  strike 
upon  them  in  the  state  of  tension  produced  by  the  action  of 
the  crico-arytenoidel  postici,  which  carry  back  the  arytenoid 
cartilages  to  which  the  ligaments  of  the  glottis  are  attached, 
whilst  the  thyroid  cartilage,  to  which  are  attached  the  other 
extremities  of  the  same  ligaments,  is  carried  forward  by  a sort 
of  tilting,  occasioned  by  the  muscles  connecting  it  with  the 
cricoid  cartilage,  (crico-thyroidei*)  the  voice  will  be  shrill, 
that  is  clear  and  piercing;  whereas  it  would  be  grave,  if  the 
arytenoid  cartilages  being  brought  forwards  by  the  action  of 
the  crico-arytenoidei  obliqui,  and  the  thyro-arytenoidei  mus- 
cles, the  vocal  strings,  relaxed,  executed  less  frequent  vibra- 
tions? 

It  has  been  objected  to  Ferrein,  that  to  perform  the  office  of 
vibrating  strings,  the  ligaments  of  the  glottis  are  neither  dry, 
nor  tense,  nor  insulated,  the  three-fold  condition  required  for 
the  production  of  sound,  in  the  instruments  to  which  this  anato- 
mist has  compared  the  larynx:  but  for  all  the  incompleteness  of 
their  resemblance  to  strings,  the  ligaments  of  the  glottis,  similar 

*Tlie  arytenoid  muscle  is  used  in  the  formation  of  acute  sounds,  for  bring- 
ing' together  the  two  arytenoid  cartilages. 


OF  VOICE  AND  SPEECH. 


499 


to  the  vibratory  bodies,  serving  as  mouth-pieces  to  wind-instru- 
ments, such  as  the  reed  of  the  oboe,  the  mouth-hole  of  flutes, 
the  lips  themselves  in  the  horn,  do  not  the  less  contribute  to 
the  formation  and  varied  inflexions  of  the  vocal  sound.  It  is  the 
more  difficult  to  set  aside  their  influence  altogether,  inasmuch 
as  their  state  of  tension  coincides  always  with  the  contraction 
of  the  glottis,  and  the  two  conditions  producing  the  same  effect, 
it  is  difficult  to  determine  if  it  be  due  to  one  rather  than  the 
other,  as  it  is  impossible  to  decide  whether  it  be  to  the  en- 
largement of  the  opening,  or  the  relaxation  of  the  ligaments, 
that  the  grave  tones  are  owing.  A last  reason,  which,  I think, 
should  make  the  larynx  be  considered  as  serving  at  once  the 
purposes  of  a wind  and  stringed  instrument,  is,  that  the  liga- 
ture or  section  of  the  recurrent  nerves,  which  give  to  its  muscles 
their  contractility,  takes  away  the  voice:  so  that  there  is 
evidently  required  some  kind  of  action  in  the  sides  of  the 
opening. 

When  we  wish  to  speak  low,  we  contract  but  slightly,  or  not 
at  all,  the  muscles  of  the  larynx,  whose  action  is  entirely  under 
the  direction  of  the  will.  The  column  of  air  meeting  then  in  its 
passage  along  the  glottis,  only  relaxed  parts,  and  little  capable 
of  vibration,  the  vocal  sound  is  no  longer  produced.  The  perma- 
nent extinction  of  the  voice  must  depend,  in  most  cases,  on 
palsy  of  the  vocal  or  laryngeal  muscles. 

It  appears  then,  that,  rejecting  the  opposite  and  exclusive 
explanation  of  Ferrein  and  Dodart,  we  are  to  consider  the 
larynx  as  an  instrument  combining  the  advantages,  and  exhibit- 
ing the  double  mechanism  of  wind  and  stringed  instruments; 
it  is  on  this  account  that  it  surpasses  all  musical  instruments, 
by  the  extent,  the  perfection,  and  above  all,  by  the  inexhausti- 
ble variety  of  its  effects.  There  is  no  one,  that  has  heard,  at  a 
concert,  a solo  on  the  French  horn  by  an  able  performer,  but 
has  been  struck  by  the  resemblance  of  the  effects  of  this  instru- 
ment, and  those  of  the  human  voice.  It  is  because  the  vibrating 
body  at  the  mouth-piece  of  the  instrument  is  alive:  it  is  because 
the  lips,  like  the  sides  of  the  glottis,  are  moveable;  the  opening 
of  the  mouth  dilates  and  contracts,  and,  at  the  same  time,  its 
edges  are  relaxed  or  stiffened  by  the  contraction  of  the  muscles 
©f  the  lips. 


OP  VOICE  AND  SPEECH. 


500 

The  modifications  of  the  voice  depend,  not  only  on  the 
varied  sizes  of  the  opening  of  the  glottis,  and  of  the  tension  of 
its  ligaments,  but  further  on  the  degree  of  length  of  the  trachea. 
The  singer  who  runs  down  the  whole  scale  of  sounds,  from 
highest  to  lowest,  visibly  shortens  the  neck  and  the  trachea, 
whilst  in  ascending,  he  stretches  them  out. 

The  force  of  the  voice*  depends  on  the  volume  of  air  that 
ina)'  be  expelled  from  the  lungs  at  once,  and  on  the  degree  of 
aptness,  in  the  parietes  of  the  canals  by  which  it  is  given  out. 
Birds,  whose  body  is  all  aerial,  have  a voice  very  strong  for 
their  bulk.  Their  trachea,  furnished  with  a double  larynx,  is 
almostf  entirely  cartilaginous.  It  is  especially  so  in  certain 
screaming  birds,  as  the  jay,  and  some  others:  whilst  it  is  nearly 
all  membranous  in  the  hedge-hog,  a small  quadruped,  whose 
cries  are  almost  imperceptible. 

The  hissing  of  serpents,  and  the  croaking  of  frogs,  are  heard 
to  some  distance,  because  these  creatures  can  send  out  a large 
quantity  of  air,  at  once,  from  their  vesicular  lungs;  and  in  the 
last,  because  the  vocal  strings  are  completely  insulated  from 
the  coats  of  the  larynx,  with  which  in  other  animals  they  are 
continuous. 

The  voice  of  men  is  strong  according  to  the  capacity  of  the 
chest.  It  is  always  weaker  after  meals,  when  the  stomach  and 
intestines,  distended  with  food,  push  up  the  diaphragm  and 
resist  its  descent.  The  voice,  formed  in  the  passage  of  the  air 
along  the  glottis,  acquires  much  force  and  intensity,  becomes 
much  more  sonorous,  by  the  reverberations  of  the  sound  in  the 
mouth  and  in  the  nasal  cavities.  It  is  \veakened  and  disagree- 
ably impaired,  when  a polypus  of  the  nasal  canals,  or  of  the 
throat,  or  the  destruction  of  the  roof  of  the  mouth,  prevents 
the  air  from  passing  along  the  nasal  canals,  and  their  various 
sinuses.  The  voice  is  then  said  to  be  nasal,  though,  in  truth,  it 
suffers  from  want  of  the  modifications  it  should  receive  in  the 
cavities  belonging  to  the  nose. 

• Sailors,  and  those  that  live  on  the  banks  of  ^eat  rivers,  have  commonly 
strong  voices  from  being  obliged  to  overpower,  with  the  voice,  the  noise  of 
the  waves,  which  hgs  constrained  them  to  a great  habitual  exertion  of  iu 
organs. 

t See  the  Memoirs  of  M.  Cuvier  on  the  double  laryn.x,  and  on  the  voice  of 
birds. 


OP  VOICE  AND  SPEECH. 


501 

CXCV.  Of  speech.  To  ■whisper  is  to  articulate  very  weak  - 
sounds,  which,  in  truth,  deserve  not  the  name  of  voice,  since 
they  scarcely  exceed  the  sound  which  always  accompanies  the 
passage  of  air  in  expiration.  Man  only  can  articulate  sound, 
and  enjoys  the  gift  of  speech.  The  particular  disposition  of  the 
mouth,  of  the  tongue,  and  lips,  makes  all  pronunciation  impos° 
sible  to  quadrupeds.  The  monkey,  in  whom  these  parts  have 
the  same  conformation  as  in  man,  would  speak  like  him,  if  the 
air  as  it  leaves  the  larynx,  were  not  diffused  into  the  hyo-thyroid 
cavities,  which  are  membranous  in  some,  cartilaginous  and  even 
bony  in  the  howling  monkey,  whose  cry  is  so  hoarse  and  me- 
lancholy. Every  time  that  the  animal  would  utter  his  cry,  these 
sacs  swell,  then  empty  themselves,  so  that  he  is  not  able,  at  will, 
to  sLippl)’^  to  the  different  parts  of  his  mouth  the  sounds  they 
might  articulate.* 

Articulated  sounds  are  represented  by  letters  which  express 
their  whole  force.  One  cannot  reflect  on  this,  without  seeing 
what  an  advance  man  made  towards  the  perfection  of  his  na- 
ture, when  he  invented  these  signs  for  the  preservation  and 
transmission  of  his  thoughts.  The  vocal  sounds  are  expressed 
by  the  letters  called  vowels.,  that  is  to  say,  which  the  voice  fur- 
nishes almost  completely  formed,  and  which  need,  for  their 
articulation,  nothing  more  than  the  more  or  less  opening  of  the 
mouth,  hy  the  separation  of  the  jaws  and  of  the  lips.  We  pro- 
nounce, without  effort,  the  letters  A,  E,  I,  O,  U;  they  are  the 
first  the  child  utters;  they  appear,  besides,  to  cost  him  less  study 
than  the  consonants.  These,  which  form  the  most  numerous 
class  of  the  letters  of  the  alphabet,  serve  only,  as  their  name 
indicates,  to  bind  together  the  vowels.  Their  pronunciation  is 
always  less  natursil,  and  consequently  more  difficult.  Accord- 
ingly, it  is  observed,  that  the  most  harmonious  languages,  the 
most  grateful  to  the  ear,  are  those  which  use  fewest  conso- 
nants and  most  vowels.  It  is  in  this  point  especially,  that 
the  Greek  tongue  surpasses  all,  ancient  and  modern;  that,  of 
dead  languages,  Latin  holds  the  second  place;  and  lastly,  that 

* In  the  ass,  an  analogous  structure  is  observed. 

f — Graiis  dedit  ore  rotundo 
Musa  loqui. — Hokat. 


OF  VOICE  AND  SPEECH. 


502 

Russian,  Italian,  and  Spanish,  are  more  agreeable  in  pronun- 
ciation, than  French,  and  still  more  than  languages  of  Teuto- 
nic origin,  as  English,  German,  Dutch,  Swedish,  Danish,  &c. 
Among  some  northern  nations,  all  articulated  sounds  appear  to 
issue  from  the  nose  or  the  throat,  and  make  a disagreeable  pro- 
nunciation, no  doubt,  because  it  requires  greater  effort,  and  he 
who  listens  sympathizes  in  the  difficulty  which  seems  to  be  felt 
by  him  who  speaks.  Would  it  not  seem  that  the  inhabitants  of 
cold  countries  have  been  led  to  use  consonants  rather  than 
vowels,  because  the  pronunciation,  not  requiring  the  same 
opening  of  the  mouth,  does  not  give  the  same  room  to  the 
continual  admission  of  cold  air  into  the  lungs.  The  gentle 
pacific  nature  of  the  inhabitants  of  Otaheite,  and  of  the  other 
Fortunate  Isles  of  the  South  Sea,  is  shown  in  the  words  of 
their  language,  in  which  are  abundance  of  vowels;  whilst  the 
hard  and  barbarous  speech  of  the  Esquimaux,  of  the  people  of 
Labrador,  and  New  Zealand,  is  the  natural  consequence  of 
the  rigor  of  their  climate,  the  barrenness  of  their  soil,  and 
their  ferocious  and  warlike  habits. 

The  distinction  of  letters,  into  vowels  and  consonants,  has 
not  been  thought  sufficient:  they  have  been  further  distinguished 
according  to  the  parts  which  are  more  especially  engaged  in  the 
mechanism  of  their  pronunciation.  Thus  we  remark  the  labial^ 
oral^  nasal  and  lingual  vowels^  and  semi-vowels,  M,  N,  R,  L, 
which  bear  different  names,  according  as  the  tongue  in  articulat- 
ing them,  strikes  the  roof  of  the  mouth,  the  teeth,  or  the  lips; 
lastly,  explosive  consonants,  K,  T,  Q,  G,  D,  B,  P,  and  sibilant, 
H,  X,  Z,  S,  J,  V,  F,  C,  which  are  more  numerous  and  more 
frequently  employed  in  languages  of  more  difficult  pronuncia- 
tion. If  information  on  this  subject  could  be  of  real  utility,  I 
should  explain  the  mechanism  of  the  pronunciation  of  every 
letter  of  the  alphabet,  at  the  risk  of  furnishing  a new  scene  to 
the  Bourgeois  Gentilhomme. 

CXCVI.  Singirig,  stammering,  dumbness,  ventriloquism, 
Singingxs  nothing  more  than  voice  modulated,  that  is,  running 
over  with  varying  rapidity,  the  different  degrees  of  the  harmonic 
scale,  passing  from  the  grave  to  the  acute,  and  from  the  acute 
to  the  grave,  with  expression  too  of  the  intermediate  tones. 
Though,  in  general,  our  song  is  spoken,  speech  is  not  necessary 


or  VOICE  AND  SPEECH. 


503 


to  it.  This  action  of  the  organs  of  the  voice  requires  more  ef- 
forts and  motions  than  speech:  the  glottis  enlarges  or  contracts, 
the  larynx  rises  or  descends,  the  neck  stretches  out  or  is  drawn 
in;  inspiration  is  accelerated^  prolonged,  or  slackened;  expira- 
tion is  long,  or  short  and  abrupt.  Accordingly  all  these  parts  are 
more  fatigued  than  by  speech,  and  it  is  impossible  for  us  to  sing 
as  long  as  we  speak. 

Whatever  Rousseau  may  have  said,  in  his  Dictionary  of 
Music,  singing  maybe  regarded  as  the  most  natural  expression 
of  the  emotions  of  the  soul,  since  the  least  civilized  nations  so 
use  it  in  their  songs  of  war  and  love,  of  joy  and  mourning:  and 
as  every  affection  of  the  mind  modifies  in  some  way  the  voice, 
music,  which  is  only  imitated  song,  can  by  the  aid  of  sounds, 
paint  love  or  rage,  sadness  or  joy,  fear  or  desire,  can  produce 
the  emotions  of  these  different  states,  can  thus  sway  the  course 
of  our  ideas,  and  direct  at  pleasure  the  operations  of  the  un- 
derstanding, and  the  acts  of  the  will.*  Of  all  the  instruments 
which  this  art  employs,  the  vocal  organ  of  man  is  indisputably 
the  most  perfect,  that  from  which  the  most  agreeable  combina- 
tions and  the  most  varied  may  be  obtained.  Who  is  there  that 
knows  not  the  property  of  the  human  voice  to  lend  itself  to  all 
accents,  and  to  imitate  all  languages?]  I will  observe,  on  the 
occasion  of  song,  that  it  is  especially  consecrated  to  the  expres- 
sion of  tender  sentiments  or  movements  of  passion,  and  that  it 
is  turning  it  aside  from  its  natural  or  primitive  destination,  to 
employ  it  in  situations  where  no  emotion  can  be  supposed.  It  is 
this  that  makes  the  recitative  of  our  operas  so  intolerably  tire- 
some, and  throws  such  ludicrousness  over  dialogues  where  the 
speakers  converse  singing,  on  the  most  indifferent  matters. 
Languages  abounding  in  vowels,  are  thereby  fitted  to  song,  and 
favour  the  growth  of  musical  genius.  It  is  perhaps  their  smooth 
and  sonorous  language  that  has  given  to  the  music  of  the  Ita- 
lians, its  superiority  over  that  of  other  countries.]:  The  declama- 

* See  Gretry,  Essais  sur  la  ATusique,  &c. 

f See  in  the  Amceptologie  Francaise,  or  Art  de  prendre  tontes  sortes  d’Oisectux, 
the  way  in  which  they  are  drawn  into  snares  by  counterfeiting  their  song. 

f This  pre-eminence  has  been  strongly  contested,  especially  in  France, 
where  towards  the  middle  of  the  last  century,  a war  arose  on  the  subject,  in 
which  her  whole  literature,  split  into  two  factions,  fought  for  the  superiority  of 
Piccini  and  Gluck.  Out  of  the  heaps  of  writings  in  verse  and  in  prose,  with  which 


«F  VOICE  AND  SPEECH. 


504 

tion  of  the  ancients  was  much  more  removed  than  our  own,  from 
the  common  tone  of  conversation,  approached  nearer  to  music, 
and  might  be  noted  like  real  song. 

The  pleasantness,  the  precision  of  the  voice,  the  extent  and 
variety  of  inflexions  of  which  it  is  capable,  depend  on  the  good 
conformation  of  its  organs,  on  the  flexibility  of  the  glottis,  the 
elasticity  of  the  cartilages,  the  particular  disposition  of  the  dif- 
ferent parts  of  the  mouth  and  nasal  canals,  &c.  It  would  be 
enough  that  the  two  halves  of  the  larynx,  or  the  two  nasal  canals, 
were  unequally  developed  to  prevent  precision  and  distinctness 
of  voice. 

Stammering  is  a vice  of  pronunciation  too  well  known  to 
make  it  necessary  to  define  it.  A tongue  too  bulky  and  thick, 
—a  remarkable  diminution  of  irritability,  as  in  drunkenness,  at 
the  approach  of  apoplexy,  and  in  certain  fevers  of  a malignant 
kind, — the  too  great  length  of  the  fraenum  of  the  tongue, — by 
hindering  the  readiness  and  ease  of  its  motions,  become  causes 
of  stammering.  Or  it  may  be  produced  by  the  want  or  bad  ar- 
rangement of  several  teeth.  The  same  causes,  but  especially  the 
length  of  the  fraenum  of  the  tongue,  keep  down  this  organ 
against  the  lower  parietes  of  the  mouth,  and  hinder  its  point 
from  striking  the  anterior  part  of  the  roof  of  the  mouth  with 
the  quick  stroke  requisite  for  the  pronunciation  of  the  letter  R. 
The  name  of  burr  is  given  to  this  defect  of  speaking. 

As  for  dumbness^  it  may  be  either  accidental  or  from  birth. 
When  by  any  accident,  as  from  a gun-shot  wound,  a cancerous 
tumour  which  has  rendered  necessary  the  extirpation  of  part  of 
the  tongue,  that  organ,  so  far  destroyed,  is  no  longer  able  to 
apply  itself  to  the  different  parts  of  the  parietes  of  the  mouth 
and  combine  its  motions  with  those  of  the  lips,  then  the  person 
becomes  dumb,  that  is  to  say,  deprived  of  speech.  He  has  still 
voice,  or  the  faculty  of  uttering  sounds:  he  may  even  articulate, 
if  he  supply,  by  mechanical  means,  the  parts  of  the  tongue,  lips, 
or  roof,  the  want  of  which  hinders  his  pronunciation. 

It  is  not  so  with  the  dumb  from  birth.  Frequently,  all  parts 

the  contest  was  carried  on,  a fe  w epigrams  will  be  remembered,  the  letter  of 
Rousseau  on  French  music,  and  the  little  work  of  D’Alembert  on  the  liberty 
of  Music.  Marmontel  too  has  made  these  disputes  the  subject  of  an  unpub- 
lished Poem,  under  the  name  of  Voyages  de  Polvmnie. 


OF  VOICE  AND  SPEECH. 


505 


of  the  mouth  are  perfect  in  their  conformation,  and  yet  the 
child  cannot  attain  to  speech.  Such  is  the  case  of  a little  boy  of 
three  years  and  a half  old,  who  has  been  brought  to  me,  to 
divide  his  frasnum  linguae.  Sometimes,  however,  the  tongue 
adheres  to  the  lower  part  of  the  mouth,  because  the  internal 
membrane  of  that  cavity  is  reflected  over  its  upper  surface,  long 
before  it  reaches  the  middle  line  of  the  inferior  surface.  In 
other  cases,  the  edges  of  the  tongue  adhere  to  the  gums. 

Sometimes,  also,  the  tongue  is  really  paralytic;  such  was  the 
case  of  the  son  of  Crcesus,  whose  wonderful  story  is  related  by 
Herodotus.* 

In  the  deaf  and  dumb  from  birth,  the  dumbness  always  arises 
from  the  deafness:  this  at  least  is  what  M.  Sicard  has  observed 
in  the  great  number  of  pupils  committed  to  his  care:  which  has 
led  him  to  say,  that,  in  them,  the  want  of  speech  should  bear 
the  name  not  of  dumbness,  but  of  silence.  It  is  owing  entirely 
to  the  absolute  ignorance  of  sounds,  and  of  their  force  repre- 
sented by  the  letters  of  the  alphabet;  the  organs  of  voice  show 
no  trace  of  injury:  they  are  well  fitted  for  fulfilling  the  purposes 
to  which  they  were  allotted  by  nature:  but  they  remain  inactive 
because  the  deaf  child  cannot  be  taught  to  use  them. 

It  was  necessary,  therefore,  as  the  ear  was  closed,  to  address 
to  other  senses  the  speech  he  must  endeavour  to  imitate.  His 
eye  must  be  made  to  watch  the  motionsf  of  the  lips  and  tongue: 
his  hand  to  feel  the  vibrations  and  utterance  of  sound,  and  thence 
he  must  learn  to  use  his  organs  of  speech:  this  has  been  done. 
What  Pereira  had  begun,  Sicard  has  brought  to  perfection: 
and  such  command  of  articulate  sounds  has  been  given  to  the 
deaf  and  dumb  by  birth,  as  has  enabled  them  to  utter  words, 
and  connected  discourse.  Even  something  of  inflexion  of  strong 
and  weaker  tones  has  been  taught  them,  by  using  the  arm  as  a 
regulator,  as  pedals  are  employed  to  modify  the  touches  of  the 
piano-forte. 

*This  is  the  author’s  solution  of  the  story,  not  Herodotus’s  statement, 
who  says  expressly  the  boy  was  dumb.  But  the  conjecture  is  ingenious,  and 
shows  a possibility  in  the  story,  which,  as  Herodotus  tells  it,  is  impossible. 

f It  is  known,  that  old  men,  grown  deaf,  fix  their  attention  very  closely  on. 
the  motions  of  the  lips,  as  well  as  on  the  varying  expressions  of  the  face,  to 
see  the  words  as  well  as  the  thoughts  of  those  who  are  speaking. 

3 S 


506 


OF  VOICE  AND  SPEECH. 


But  instruction  to  the  deaf  and  dumb  must  be  given  them 
by  another  language.  Written  language  they  learn,  not  as  a re- 
presentative of  speech,  but  as  hieroglyphic  characters  for  ideas: 
and  a manual  language,  in  which  each  letter  is  expressed  by 
the  position  of  the  fingers  or  hands,  is  used  as  a more  con- 
venient and  rapid  representation  of  that  hieroglyphic  language 
of  written  characters.  It  is  by  this  that  conversation  with  them 
is  best  carried  on;  and  it  is  with  an  ease  and  rapidity  which 
astonishes  those,  who  for  the  first  time,  are  witnesses  to  the 
use  of  it. 

To  conclude  this  chapter,  I have  still  to  speak  of  a pheno- 
menon, well  worthy,  by  its  singularity,  of  the  attention  of 
physiologists.  It  is  known  under  the  name  of  ventriloquism^ 
because  the  voice,  weak  and  little  sonorous,  appears  to  issue 
from  the  stomach.  There  is  now  living,  at  the  quondam  Palais- 
Royal,  at  the  Coffee-House  de  la  Grotte,  a man,  who  can  carry 
on  a dialogue  so  naturally,  that  you  would  think  you  were 
listening  to  the  conversation  of  two  people,  at  some  distance 
from  one  another,  and  quite  different  in  voice  and  tone.  I have 
observed,  that  he  is  not  inspiring  while  he  speaks  from  his 
belly,  but  that  less  air  comes  from  his  mouth  and  nostrils  than 
in  his  ordinary  speaking.  Every  time  that  he  does  so,  he  finds 
a swelling  in  the  epigastric  region;  sometimes  he  feels  wind 
moving  lower  down,  and  cannot  go  on  long  together  without 
fatigue. 

I had  at  first  conjectured  that,  in  this  man,  a great  part  of  the 
air  driven  out  by  expiration,  did  not  issue  from  the  mouth  and 
nasal  fossae,  but  that,  being  swallowed  and  carried  down  into 
the  stomach,  it  struck  against  some  part  of  the  digestive  tube, 
and  produced  a real  echo;  but  having  since  observed,  with  the 
greatest  care,  this  curious  phenomenon  in  M.  Fitz-James,  who 
exhibits  it  in  the  highest  perfection,  I have  satisfied  myself  that 
the  name  of  ventriloquism  no  ways  suits  it;  since  its  whole 
mechanism  consists  in  a slow,  gradual,  attenuated  expiration, 
whether  for  that  purpose  the  artist  employ  the  power  of  the  will 
upon  the  muscles  of  the  parietes  of  the  chest,  or  whether  he 
holds  the  epiglottis  slightly  lowered,  by  means  of  the  root  of 
the  tongue,  of  which  he  scarcely  brings  the  point  beyond  the 
dental  arches. 


OF  VOICE  AND  SPEECH. 


507 

I find  this  long  expiration  always  preceded  by  a strong  in- 
spiration, by  means  of  which  he  introduces  into  his  lungs  a 
large  quantity  of  air  of  which  he  afterwards  husbands  the  use. 
Accordingly,  repletion  of  the  stomach  is  a great  hindrance 
to  the  action  of  M.  Fitz-James,  by  preventing  the  descent  of 
the  diaphragm  which  the  chest  would  require,  to  dilate  itself 
for  the  full  quantity  of  air  the  lungs  should  receive. 

By  accelerating  or  retarding  expiration,  he  can  imitate  dilfe- 
rent  voices,  make  it  seem  that  the  speakers,  in  a dialogue,  which 
he  carries  on  by  himself,  stand  at  different  distances,  and  pro- 
duce illusion  the  more  complete,  the  more  perfect  is  his  talent. 
No  one  equals  M.  Fitz-James  in  the  art  of  deceiving,  in  this 
respect,  the  most  wary  and  suspicious  observer. 

He  can  set  his  organ  to  five  or  six  different  tones,  pass  rapidly 
from  one  to  the  other,  as  he  does  when  he  represents  a very 
eager  discussion,  in  a popular  society  of  the  people,  imitate  the 
sound  of  a bell,  and  carry  on,  singly,  a conversation,  in  which 
one  might  think  that  several  persons  of  different  ages  and  sexes 
were  taking  parts.  But  what  completes  the  illusion,  and  especi- 
ally distinguishes  the  art  of  the  ventriloquist  from  that  of  the 
mimic,  who  can  only  counterfeit,  consists  in  the  power  of  so 
modulating  his  voice  that  one  is  deceived  as  to  the  distance  of 
the  speaker,  in  such  sort,  that  one  voice  comes  from  the  street, 
another  from  a neighbouring  apartment,  that  from  one  that  had 
clambered  up  the  roof  of  the  house,  &c.  It  is  easy  to  discern 
the  value  of  such  a talent  in  the  days  of  oracles. 


SECOND  CLASS. 


FUNCTIONS 

SUBSERVIENT  TO  THE  PRESERVATION  OF 
THE  SPECIES. 


511 


CHAPTER  X. 

ON  GENERATION. 

CXCVII.  l^IFFERENCES  of  the  sexes.  The  functions 
treated  of  in  this  chapter  are  not  necessary  to  the  life  of  the 
individual,  but,  without  them,  the  human  species  would  soon 
perish,  for  want  of  the  power  of  reproduction;  these  functions, 
destined  to  preserve  the  species,  are  entrusted  to  two  kinds  of 
organs,  belonging  to  the  two  sexes,  of  which  they  constitute 
the  principal,  though  not  the  only  difference. 

Woman,  in  fact,  does  not  differ  from  man,  in  her  genital 
organs  merely,  but  likewise  in  her  lower  stature,  in  the  delicacy 
of  her  organization,  in  the  predominance  of  the  lymphatic  and 
cellular  systems,  which  softens  down  the  projections  of  the 
muscles,  and  gives  to  all  her  limbs  those  rounded  and  graceful 
forms,  of  which  we  see,  in  the  Venus  of  Medicis,  the  inimita- 
ble model.  In  woman,  sensibility  is  also  more  exquisite;  and 
with  less  strength,  her  mobility  is  greater.  The  female  skeleton 
even  is  easily  distinguished  from  that  of  the  male,  by  striking 
differences.  The  asperities  of  the  bones  are  less  prominent;  the 
clavicle  is  less  curved,  the  chest  shorter  but  more  expanded, 
the  sternum  shorter  but  wider;  the  pelvis  more  capacious,  the 
thigh  bones  more  oblique,*  &c.  In  a dissertation  on  physical 
beauty,  read  by  Camper  to  the  Academy  of  design,  at  Amster- 
dam, this  celebrated  physiologist  showed,  that,  in  tracing  the 
forms  of  the  male  and  female  body  within  two  elliptical  areas, 
of  equal  size  in  both,  the  female  pelvis  would  extend  beyond 
the  ellipsis,  and  the  shoulders  be  within;  while,  in  man,  the 
shoulders  would  reach  beyond  their  ellipsis,  and  the  pelvis  be 
contained  within  its  limits. 

The  general  characters  of  the  sexes  are  so  marked,  that  it 

* Compare  the  beautiful  plates  of  the  male  and  female  skeleton  by  Albinus 
and  ScEmmerin^. 


512 


ON  GENERATION. 


would  be  possible  to  distinguish  a male,  merely  by  seeing  a part 
of  his  body  naked,  even  though  this  part  should  not  be  covered 
with  hairs,  and  should  have  none  of  the  principal  attributes  of 
virility.  Should  this  difference  of  organization  and  character  be 
ascribed  to  the  influence  of  the  sexual  organs  upon  the  rest  of 
the  body?  Does  the  uterus  impress  on  the  sex  all  its  charac- 
teristic modifications,  and  is  it  just  to  say  with  Vanhelmont: 
Propter  solum  uterum  mulier  est,  id  quod  est;  the  uterus  alone 
makes  woman  what  she  is.  Though  this  viscus,  very  evidently, 
re-acts  on  the  whole  system  of  the  female,  and  seems  to  draw 
under  its  control  nearly  the  whole  of  the  actions  and  affections 
of  woman,  I am,  nevertheless,  of  opinion,  that  it  is  far  from 
being  the  only  cause  of  her  distinguishing  characteristics,  since 
these  may  be  recognized,  from  the  earliest  period  of  life,  when 
the  uterine  system  is  far  from  having  attained  its  full  activity. 
A very  singular  fact,  recorded  by  Professor  Cailliot,  in  the 
second  volume  of  the  Memoirs  of  the  hledical  Society  of 
Paris,  proves  better  than  all  the  reasoning  in  the  world,  how 
much  the  character  of  the  sex  is  independent  of  the  influence  of 
the  uterus.  A female  was  born  and  grew  up  with  all  the  exter- 
nal characteristics  of  her  sex.  At  the  age  of  twenty-one,  she 
wished  to  yield  to  her  desires,  but  found  it  impracticable;  there 
was  nothing  beyond  the  vulva,  in  other  respects,  well  formed. 
A small  canal,  between  two  and  three  lines  in  diameter,  occu- 
pied the  place  of  the  vagina,  and  terminated  in  a cul  de  sac, 
and  was  about  an  inch  in  depth.  The  most  accurate  examina- 
tions, by  introducing  the  sound  into  the  bladder,  and  the  finger 
up  the  rectum,  discovered  nothing  like  the  uterus.  With  the 
finger  in  the  rectum,  the  convexity  of  the  sound  in  the  bladder 
could  be  distinctly  felt,  so  that  it  was  evident  that,  between  the 
lower  part  of  the  bladder  and  the  anterior  part  of  the  rectum, 
there  lay  no  organ  corresponding  to  the  uterus.  The  young 
woman  had  never  been  subject  to  the  periodical  evacuation 
which  accompanies  or  precedes  the  time  of  puberty.  No  he- 
morrhage supplied  the  place  of  this  excretion.  She  experienced 
none  of  the  indispositions  that  are  occasioned  by  the  absence 
of  menstruation;  she  enjoyed,  on  the  contrary,  the  most  perfect 
health;  she  was  deficient  in  none  of  the  other  characteristics  of 
her  sex,  only  that  her  breasts  were  small.  At  the  age  of  twenty- 


ON  GENERATION. 


513 

six  or  twenty-seven,  she  became  subject  to  a pretty  frequent 
evacuation  of  bloody  urine.  May  not  this  affection,  which  re- 
curred at  irregular  periods,  be  considered  as  a means  by  which 
nature  supplied  the  deficiency  of  the  menstrual  evacuation?  The 
bladder,  in  that  case,  would  fulfil  the  office  of  the  uterus,  and 
its  capillary  vessels  must  have  been  considerably  evolved. 

The  reproduction  of  the  species  is,  in  woman,  the  most  im- 
portant object  of  life;  it  is  almost  the  only  destination  to  which 
nature  has  called  her,  and  the  only  duty  she  has  to  fulfil  in 
human  society.  Wherever  the  earth  is  fruitful,  and  furnishes 
man  with  abundant  means  of  providing  for  his  wants,  he  dis- 
penses with  the  services  of  woman,  in  obtaining  from  it  means 
of  subsistence;  he  releases  her  from  the  burthen  of  social  obli- 
gations. The  Asiatic  expects  from  the  women  he  maintains  in 
his  seraglio,  in  a state  of  inactivity,  nothing  but  pleasures  and 
children  to  perpetuate  his  race.  The  women  of  Otaheite  have 
no  employment  but  pleasure  and  the  duties  of  mothers.  Among 
some  of  the  savage  tribes  of  America,  man,  abusing  the  odious 
right  of  power,  tyrannizes  it  is  true,  over  woman,  and  reserving 
to  himself  all  the  advantages  of  social  life,  makes  her  bear  all 
its  weight;  but  this  exception  does  not  invalidate  the  general 
law  deduced  from  observation  of  aU  nations.  Whatever  with- 
draws woman  from  this  primitive  destination;  whatever  diverts 
her  from  this  end,  is  to  her  injury;  it  is  the  scope  of  all  her 
actions  and  habits;  every  thing,  in  her  physical  organization, 
has  evident  reference  to  it.  Of  all  the  passions  in  woman,  love 
has  the  greatest  sway;  it  has  even  been  said  to  be  her  only 
passion.  It  is  true,  that  all  the  others  are  modified  by  it,  and 
receive  from  it  a peculiar  cast,  w^hich  distinguishes  them  from 
those  of  men.* 

We  will  enter  n^  further  into  the  examination  of  the  general 
differences  which  characterize  the  two  sexes;  no  one  has  entered 
more  deeply  into  this  subject,  or  has  treated  It  in  a more  inter- 

* Fontenelle  used  to  say  of  the  devotion  of  some  womeri:  Or.e  may  see  that 
lone  has  been  h^re.  It  has  been  said  in  speaking  of  St.  Theresa:  To  love  God 
is  still  to  love.  Thomas  maintains  that,  viith  woman,  a man  is  more  than  a 
nation.  Love  is  but  an  episode  in  the  life  of  man;  it  is  the  -whole  history  of  the  life 
of  -woman.  (Madame  de  Stael.) 

3 T 


514 


ON  GENERATION. 


esting  manner,  than  M.  Roussel,  in  an  excellent  work,  intitled 
Systems  physique  et  moral  de  la  femme. 

CXCVIII.  Hermaphrodism.  Hermaphrodism,  or  the  union 
of  the  two  sexes  in  the  same  individual,  is  impossible  in  man, 
and  in  the  numerous  class  of  red-blooded  animals.  There  is  on 
record,  no  well  authenticated  case  of  such  a combination;  and 
all  the  hermaphrodites  that  have  been  hitherto  met  with,  were 
beings  imperfectly  formed;  in  whom  imperfect  male  organs,  or 
female  organs  unnaturally  enlarged,  rendered  the  sex  dubious. 
None  was  ever  found  that  had  the  power,  by  itself,  of  begetting 
a similar  being  to  itself:  the  greater  number  were  incapable  of 
reproduction;  the  imperfection,  or  the  faulty  conformation  of 
their  organs,  condemned  them  to  barrenness.  Such  was  the  case 
with  the  hermaphrodite  mentioned  by  Petit  of  Namur,  in  the 
Memoirs  of  the  Academy  of  Sciences;  with  that  one  whose 
case  is  related  by  Maret,  in  the  Memoirs  of  the  Academy  of 
Dijon,  and  with  all  those  to  be  found  in  the  records  of  the 
Medical  Society,  which  contain  the  greatest  number  of  facts  of 
this  kind. 

But  though,  in  man,  and  in  all  beings  that  most  resemble 
him,  in  their  organization,  complete  hermaphrodism  has  never 
been  met  with,  it  is  a frequent  occurrence  among  the  white- 
blooded  animals,  and  especially  among  the  plants  that  occupy 
the  lowest  part  of  the  scale  of  organized  beings.  The  same  is 
observed  in  polypi,  in  several  kinds  of  worms,  in  oysters,  and 
snails.  The  latter  present  a singular  variety  of  hermaphrodism, 
in  this,  that  the  male  and  female  organs  being  combined  in  the 
same  individual,  it  is  still  singly  not  capable  of  generation,  but 
is  obliged  to  copulate  with  another  being  likewise  an  herma- 
phrodite, so  as  to  receive  from  friction  and  other  means  of  irri- 
tation, the  excitement  to  the  act  of  reproduction. 

In  the  immense  tribe  of  monoecia  plants,  the  male  and  female 
organs  are  combined  on  one  stalk,  and  even  sometimes  within 
the  same  flower.  A number  of  stamina  surround  one  or  more 
pistils,  shed  on  the  stigma  their  fertilizing  dust  or  pollen,  which 
is  conveyed  along  the  canal  of  the  style,  into  the  ovary,  there 
to  impregnate  the  seeds,  by  means  of  which  the  species  are 
perpetuated.  The  same  vegetable  species  containing  sometimes 
male  and  female  individuals,  the  sexes  may  be  at  considerable 


ON  GENERATION, 


51S 

distances  from  one  another;  the  seminal  dust  is,  in  that  case, 
conveyed  by  the  air,  from  the  male  to  the  female.  This  is  the 
case  with  palm  trees,  on  which  Gleditsch  made  his  first  obser- 
vations on  the  generation  of  plants;  hemp,  spinage,  mercuri- 
alis,  &c. 

CXCIX.  It  is  a distinction  of  the  human  species  that,  in 
them,  the  functions  of  generation  are  not  under  the  influence  of 
the  seasons.  The  lower  animals,  on  the  contrary,  draw  together, 
and  pair  at  stated  periods  of  the  year,  and  seem  afterwards  to 
forget  the  enjoyments  of  love,  that  they  may  attend  to  their 
other  necessities.  Thus,  wolves  and  foxes  copulate  in  the  mid- 
dle of  winter;  deer  in  autumn,  most  birds  in  spring.  Man 
alone  seeks  his  partner  at  all  seasons  of  the  year,  and  impreg- 
nates her  under  all  latitudes  and  in  all  temperatures.  This  pri- 
vilege is  not  so  much  the  consequence  of  his  peculiar  constitu- 
tion, as  a result  which  he  derives  from  his  industry;  protected 
by  the  shelters  which  he  constructs  against  the  inclemency  of 
the  seasons,  and  the  variations  of  the  atmosphere;  always  capa- 
ble of  gratifying  his  physical  wants  by  help  of  the  stores  which 
his  foresight  has  led  him  to  collect,  he  can,  at  all  times,  indulge 
in  the  enjoyments  of  love.  The  domestic  animals  which  we 
have,  in  great  measure,  removed  from  the  influence  of  external 
causes,  bring  forth  almost  indiscriminately,  at  all  seasons  of  the 
year.  To  prove  still  further,  that  it  is  from  counteracting,  by 
the  resources  of  his  industry,  the  influence  of  nature,  that  man 
has  succeeded  in  resisting  the  influence  of  the  seasons,  in  the 
reproduction  of  his  species,  I may  observe,  that  this  effect  of 
temperature  is  more  absolute,  the  farther  the  species  is  from 
man:  hence  the  spawn  of  fishes  and  frogs  is  productive  sooner 
or  later,  according  to  the  eai  liness  or  lateness  of  the  season,  and 
thus,  a great  number  of  insects  depend  on  the  heat  of  the 
weather  for  their  powers  of  reproduction,  and  for  their  exis- 
tence. 

CC.  Of  the  organs  of  generation  in  man.  Aristotle,  Galen, 
and  their  verbose  commentators,  have  expressed  the  analogy 
which  subsists  between  the  organs  of  generation,  in  the  two 
sexes,  by  saying  that  they  differ  only  in  their  position,  being 
external  in  man,  and  internal  in  woman.  There  is,  in  fact,  a 
considerable  resemblance  between  the  ovaria  and  the  testicles, 


S16 


ON  GENERATION. 


the  fallopian  tubes  aud  the  vasa  deferentia,  the  uterus  and  the 
vesiculse  seminales,  the  vagina,  the  external  organs  of  genera- 
tion in  woman,  and  the  male  penis.  The  former  secrete  the 
seminal  fluid,  and  furnish,  in  man  or  in  woman,  a matter  essen- 
tial to  generation  (ovaria  and  testicles).  The  fallopian  tubes, 
like  the  vasa  deferentia,  convey  this  fluid  into  receptacles  where 
it  has  to  remain  for  some  time  (uterus  and  vesiculae  seminales). 
Thesd  contractile  cavities,  which  serve  as  reservoirs  to  the 
semen,  or  its  product,  part  with  these  substances,  when  they 
have  remained  within  them  a suflicient  length  of  time;  lastly, 
the  vagina  and  penis  serve  to  expel  them.  However  striking 
such  analogies  may  be,  we  are  not  justified  in  inferring  a per- 
fect resemblance  between  the  organs  of  generation  in  the  two 
sexes.  Each  of  them  fulfils,  in  the  act  of  reproduction,  func- 
tions perfectly  distinct,  though  of  reciprocal  necessity. 

The  prolific  fluid  is  secreted  by  the  testicles;  these  organs 
are  two  in  number,  covered  by  several  coats,  one  of  which, 
covered  by  the  skin,  and  known  under  the  name  of  scrotum, 
resembles  a bag  containing  both  these  organs;  it  contracts  on 
the  application  of  cold,  is  relaxed  by  heat,  and  possesses  a de- 
gree of  contractility  more  evident  than  in  the  other  parts  of  the 
cutaneous  tissue.  The  dartos  forms  a second  cellular  envelope 
common  to  each  testicle.  The  tunica  vaginalis,  a serous  mem- 
brane, affords  an  immediate  covering  to  them,  and  reflecting 
itself  over  their  surface,  is  disposed  with  regard  to  them,  as  the 
peritoneum  with  regard  to  ihe  abdominal  viscera,  that  is,  it  does 
not  contain  them,  within  its  cavity.  Lastly,  the  testicles  are 
covered  by  a fibrous,  white,  thick,  and  very  consistent  mem- 
brane; it  is  termed  tunica  albuginea,  from  the  inner  surface  of 
which  there  arise  a considerable  number  of  membranous  laminae, 
which,  crossing  one  another,  within  its  cavitj%  form  cells  con- 
taining a yellowish  vascular  substance.  This  substance  con- 
tained within  the  tunica  albuginea,  has  so  little  consistence, 
that  it  would  very  soon  be  dissolved,  if  the  testicle  were  stripped 
of  its  outer  covering.  It  is  formed  by  the  seminiferous  tubes, 
which  are  small  capillary  vessels  extremely  tortuous  and  coiled 
on  themselves,  arising  probably  from  the  extremities  of  the 
spermatic  arteries,  all  directed  towards  the  upper  part  of  the 
oval  formed  by  the  testicles,  joining  in  this  place,  and  forming 


6N  GENERATION,  5]^  7 

about  ten  or  twelve  tubes  which  unite  in  a cord  situated  within 
the  tunica  albuginea,  called  the  corpus  Highmorianum.  The  ten 
or  twelve  ducts  which  unite  into  a fasciculus,  and  form  this 
cord,  pass  through  the  membrane  within  which  they  are  con- 
tained, unite  into  a single  canal  which  is  convoluted,  and  forms 
a substance  called  the  epididymis.  T his  canal,  formed  by  the 
union  of  the  ducts  of  the  corpus  Highmorianum,  at  first  con- 
voluted on  itself,  becomes  less  and  less  tortuous,  as  it  ap- 
proaches the  lower  extremity  of  the  testicle;  there  it  bends 
back  and  ascends  under  the  name  of  vas  deferens^  along  the 
spermatic  cord,  as  far  as  the  inguinal  ring,  by  which  it  enters 
the  abdominal  cavity.  The  vasa  deferentia,  though  of  the  size 
of  a quill,  have  nevertheless  a very  small  cavity;  and  it  is  not 
easy  to  say  why  a capillary  tube  should  have  such  thick  parietes 
and  nearly  as  hard  as  cartilage. 

The  semen,  secreted  by  the  testicles,  is  formed  from  the 
blood  conveyed  to  them  by  the  spermatic  arteries,  long,  slenj 
der,  and  very  tortuous  vessels,  arising  from  the  aorta,  at  a very 
acute  angle.  This  fluid  is  filtered  through  the  seminiferous 
tubes,  passes  into  those  of  the  corpus  Highmorianum,  and 
thence  into  the  vasa  deferentia,  which,  after  they  have  entered 
the  abdomen,  terminate  into  the  vesiculae  seminales,  and  deposit 
into  them  the  spermatic  fluid.  The  delicacy  of  the  organization 
of  the  testicle,  the  delicacy  of  the  vessels  along  which  the 
semen  is  conveyed,  account  for  its  tendency  to  congestion,  and 
for  the  difficulty  with  which  a resolution  of  this  affection  is 
obtained. 

The  spermatic  fluid  passes  from  the  vasa  deferentia  into  the 
vesiculae  seminales,  notwithstanding  the  retrograde  direction  of 
their  course.  The  cavities  serving  as  receptacles  to  the  semen, 
resemble  in  this  respect,  the  gall-bladder.  Notwithstanding  the 
unfavourable  direction  in  which  the  ducts  of  the  liver  and  of  the 
testicles  join  their  respective  receptacles,  they  nevertheless  con- 
vey their  fluids  into  the  latter;  the  bile,  because  the  ductus  chole- 
dochus  is  pressed  by  the  coats  of  the  duodenum,  contracted  on 
itself  when  empty;  the  semen,  because  the  duct  along  which  it 
is  conveyed,  penetrating  through  the  prostate  gland,  and  open- 
ing into  the  Urethra,  by  a very  narrow  orifice,  this  fluid  flows 


ON  GENERATION. 


518 

back  more  readily  into  the  vesiculae  seminales,  than  from  the 
vas  deferens  into  the  ejaculatory  duct. 

The  vesiculae  seminales  form  two  membranous  receptacles  of 
different  capacity,  in  different  individuals;  larger  in  young  people 
and  adults,  than  in  children  and  old  people.  Their  cavity  is 
divided  into  a number  of  cells;  they  are  lined  with  a mucous 
membrane  which  secretes,  in  considerable  quantity,  a viscid 
humour  that  mingles  with  the  semen,  increases  its  quantity  and 
serves  as  a vehicle  to  it.  The  situation  of  the  vesiculas  semi- 
nales, between  the  rectum,  the  levatores  ani,  and  the  posterior 
part  of  the  bladder,  promotes  the  excretion  of  their  contents 
(which  is  chiefly  brought  about  by  the  contraction  of  their  pa- 
rietes),  by  the  compression  of  the  levatores  ani,  which  are  in  a 
state  of  convulsion  at  the  moment  of  emission.  Animals  that 
are  not  provided  with  these  seminal  receptacles,  remain  a con- 
siderable time  in  a state  of  copulation,  the  prolific  fluid  neces- 
sary to  impregnation  having  to  be  secreted  during  the  time  that 
the  copulation  lasts,  and  flowing  in  drops. 

The  ducts  formed  by  the  union  of  the  vesiculae  seminales 
with  the  vasa  deferentia,  pass  through  the  prostate  gland,  and 
open,  by  separate  orifices,  into  the  urethra,  at  the  bottom  of  a 
lacuna,  near  the  verumontanum.  The  glandular  body  in  which 
they  are  inclosed,  and  which  contains  both  the  neck  of  the  blad- 
der and  the  beginning  of  the  urethra,  does  not  exist  in  women. 
The  mucous  and  whitish  fluid,  secreted  by  the  prostate,  is  con- 
veyed by  ten  or  twelve  orifices  into  the  urethra.  This  prostatic 
fluid  mingles  with  the  semen,  adds  to  its  quantity,  is  perhaps 
emitted  first,  in  order  to  lubricate  the  internal  surface  of  the 
canal,  and  prepare  it  for  the  passage  of  the  seminal  fluid,  by 
rendering  the  internal  surface  of  the  urethra  more  slippery. 
The  use  of  the  urethra  is,  not  only  to  convey  the  semen  out  of 
the  body,  but  likewise  to  serve  in  the  excretion  of  the  urine,  and 
to  form  a part  of  the  penis.  The  latter,  destined  to  convey  the 
prolific  fluid  into  the  female  organs  of  generation,  must  be  in  a 
state  of  erection  to  perform  this  function  completely.  Erection 
being  a phenomenon  of  structure,  that  of  the  penis  will  be  con- 
sidered, after  the  description  of  the  female  organs  of  generation. 

CCII.  Of  the  female  orgatis  of  generation.  I shall  not  adopt 
the  anatomical  arrangement  generally  followed  in  this  descrip- 


ON  GENERATION. 


Slf 

tion,  but  classing  in  three  divisions,  the  different  parts  which, 
in  women,  are  subservient  to  the  genital  functions,  I shall  speak 
first  of  the  ovaria  and  fallopian  tubes,  then  of  the  uterus,  and 
in  the  last  place  of  the  vagina  and  external  parts. 

The  ovaria,  situated  in  the  female  pelvis,  connected  to  the 
uterus  by  a ligament,  receive  the  vessels  and  nerves  which,  in 
the  male,  are  sent  to  the  testicles;  they  resemble  in  form  the 
latter,  but  are  somewhat  smaller.  Do  the  ovaria  secrete  a fluid, 
which,  by  mixing  with  the  mala  semen,  produces  the  new  be- 
ing, or  is  there  detached  from  them,  at  the  moment  of  concep- 
tion, an  ovum  which  the  semen  vivifies?  Whatever  opinion  is 
adopted,  one  is  compelled  to  admit,  that  the  ovaria  prepare  a 
substance  essential  to  generation,  since  females,  in  whom  these 
parts  have  been  extirpated,  are  rendered  steril. 

It  is  likewise,  unquestionably,  along  these  membranous  tubes, 
called  fallopian,  that  this  substance,  whatever  it  may  be,  fur- 
nished by  the  ovaria,  passes  into  the  uterus,  into  which  one  of 
their  extremities  opens;  while  the  other  extremity,  broad  and 
fringed,  lies  loose  in  the  cavity  of  the  pelvis,  supported  by  a 
small  duplicature  of  the  peritoneum,  but  undergoes  a state  of 
erection  and  applies  itself  to  the  ovarium,  during  the  act  of 
coition,  and  forms  a continuous  canal  between  that  organ  and 
the  cavity  of  the  uterus.  The  external  orifice  of  the  fallopian 
tube,  called  corpus  Jimbriatum^  has  been  found  grasping  thus 
the  ovarium,  in  females  opened  immediately  after  coition.  It 
may  happen,  from  a malformation  of  the  parts,  that  the  fallo- 
pian tube  may  not  be  able  to  apply  itself  to  the  ovarium;  I dis- 
sected at  the  Hospital  de  la  Charite^  the  body  of  a woman  who 
had  been  barren;  and  found  the  corpora  fimbriata,  or  the  ex- 
panded termination  of  the  fallopian  tubes,  adhering  to  the  lateral 
parietes  of  the  pelvis,  so  that  it  was  impossible  they  should  per- 
form the  motions  required  for  impregnation. 

The  uterus,  lying  in  the  pelvis,  between  the  rectum  and  blad- 
der, is  a hollow  viscus,  in  which  the  foetus  grows  till  the  period 
of  birth.  Its  internal  part  has  been  found  separated  into  two 
cavities,  opening,  in  some  cases,  in  the  same  vagina,  and,  at 
others,  terminating  in  a vagina  that  was  double,  only  in  the 
immediate  vicinity  of  the  uterus.  Valisnieri  mentions  the  case 
of  a woman  who  had  a double  uterus,  the  one  opening  in  the 


ON  GENERATION. 


520 

vagina,  and  the  other  communicating  with  the  rectum.  Though 
the  muscularity  of  the  parietes  of  the  uterus  becomes  manifest, 
in  proportion  as  this  organ  enlarges,  during  the  progress  of  preg- 
nancy, this  hollow  muscle  may  be  said  to  differ  from  other  mus- 
cular organs,  by  the  arrangement  of  its  fibres,  which  it  is  diffi- 
cult to  discover  while  its  cavity  is  empty,  and  which  it  is  even 
impossible  completely  to  unravel,  while  it  contains  the  fostus;  its 
most  remarkable  distinguishing  character,  is  its  singular  proper- 
ty of  dilating  and  stretching  itself;  and,  at  the  same  time,  of 
gaining  in  thickness  instead  of  becoming  thinner. 

The  vagina  is  remarkable,  only  by  the  soft,  wrinkled,  and 
easily  dilated  structure  of  its  parietes.  The  upper  extremity  of 
this  oblique  canal,  which  is  directed  upward  and  backward,  em- 
braces the  Cervix  of  the  uterus,  while  its  lower  orifice  is  sur- 
rounded by  a spongy  body,  whose  cells  fill  with  blood  and 
expel  it,  like  the  corpora  cavernosa  of  the  penis  and  clitoris. 
It  is  called  plexus  retiforme;  its  turgescence,  during  erection, 
contracts  the  orifice  of  the  vagina;  the  contraction  of  the  con- 
strictor muscle,  which  answers  the  purpose  of  the  accelerator 
urinae  in  man,  and  which  lies  over  this  plexus  retiforme,  sur- 
rounds like  it,  the  entrance  of  the  vagina,  and  may,  in  the  same 
manner,  contract  the  orifice  of  this  canal. 

Besides,  this  external  orifice  is  furnished,  in  women  who 
have  had  no  connexion  with  men,  with  a membranous  fold, 
varying  in  breadth,  generally'^  semicircular,  and  called  the  hymen. 
Its  existence  is  considered  by  many  as  the  most  certain  sign 
of  virginity.  But  all  the  marks  by'  which  it  has  been  attempted 
to  obtain  a certainty  of  the  presence  of  virginity  are  very  equi- 
vocal*. The  relaxed  state  of  the  parts,  from  a great  quantity' 
of  mucus,  in  a woman  subject  to  the  fluor  alhus,  or  from  the 
blood  of  the  menstrual  discharge,  may'  make  the  hymen  yield 
and  not  rupture,  so  that  a woman  might  seem  a virgin  without 
being  such;  while  another  woman  who  has  not  lost  her  virgini- 
ty, might,  from  illness,  have  her  hymen  destroyed.  There  are, 
in  the  last  place,  persons  in  whom  the  hymen  is  so  indistinct, 
that  several  anatomists  have  doubted  its  existence. 

• " Attemen  prima  venus  debet  esse  cruenta.” — Haller. 

r 


ON  GENERATION. 


521 


The  other  external  parts  of  generation,  which  are  easily  dis- 
covered, without  the  aid  of  dissection,  cannot  be  considered  as 
merely  ornamental;  all  are,  as  will  be  shown  presently,  of  real 
utilit3%  The  folds  of  skin  which  form  the  labia  and  the  nymphse, 
yield,  during  the  delivery  of  the  fostus.  These  duplicatures  not 
only  unfold  themselves,  but  likewise  undergo  a degree  of  ex- 
tension, their  tissue  being  moister,  softer,  and  more  extensible 
than  that  of  the  skin.  The  mons  veneris,  the  hairs  which  cover 
it,  the  clitoris  which  resembles  an  imperfect  penis,  seem  merely 
organs  of  voluptuousness;  but  is  not  pleasure  itself  an  element 
in  the  act  bv  which  the  human  species  is  reproduced? 

CCIII.  Of  conception.  When  a chemical,  mechanical,  or 
mental  irritation  excites  the  action  of  the  genital  organs,  the 
penis  elongates  itself,  becomes  turgid  and  stiff,  from  the  accu- 
mulation of  blood  within  the  cells  of  the  corpus  cavernosum, 
and  within  those  of  the  corpus  spongiosum  of  the  urethra.* 
The  turgescence  of  these  two  parts  of  the  penis  should  be 
simultaneous,  to  render  the  erection  complete.  It  has  been 
thought  that  this  phenomenon  might  be  accounted  for,  by  the 
compression  of  the  pudic  veins,  which  are  situated  between  the 
symphysis  pubis  and  the  root  of  the  penis,  which,  as  long  as  the 
erection  lasts,  is  compressed  against  the  bone  by  the  erector 
muscles.  But  far  from  elevating  the  penis,  the  muscles  of  the 
perineum,  especially  the  ischio  cavernous  (erectoris penis P)  tend 
to  depress  it.  The  blood  which  distends  the  corpora  cavernosa 
of  the  penis,  and  the  corpus  spongiosum  of  the  urethra  and 
glans,  which  is  itself  the  expanded  extremity  of  the  urethra, 
does  not  stagnate  in  their  cells,  only  there  is  a greater  quantity 
of  blood  in  them  than  usual;  the  irritation  increasing,  in  a re- 
markable manner,  the  action  of  the  arteries.  Erection,  always 
proportioned  to  the  degree  of  the  stimulus,  ceases,  when  the 
cause  of  irritation  no  longer  acts  on  the  penis;  in  the  same 
manner  that  an  inflammatory  tumour  is  discussed,  when  the 
cause  is  removed. f In  this  voluptuous  dilatation,  the  urethra  is 

* “ Penis  adest,  ita  constructus,  ut  stimulo  corporeo  sive  mentali  iiTitatus, 
turgeat  et  obrigescat,  seque  erigat,  postea  detiimescat,  et  collabatur.”— 
Creve. 

■j-  The  animal  heat  is  somewhat  augmented,  during’  erection,  as  well  as  in 
inflammation.  The  temperature  of  the  blossoms  of  the  arum  rises  several 
degrees  above  that  of  the  atmosphere,  at  the  moment  of  impregnation. 

3 IT 


522 


ON  GENERATION. 


brought  into  a state  of  erection,  being  put  on  the  stretch  by  the 
penis  which  is  elongated,  its  curves  are  straightened,  the  irri- 
tation is  propagated  from  the  external  to  the  internal  parts,  to 
the  vesiculffi  seminales  and  the  testicles.  These  swell,  and  their 
secretion  is  increased  as  they  receive  a gentle  degree  of  motion 
from  the  action  of  the  scrotum,  which  becomes  wrinkled  and 
draws  them  up  towards  the  abdomen,  and  by  the  action  of  the  cre- 
master muscle,  whose  expansion  forms  between  the  tunica  vagi- 
nalis and  the  dartos,  what  has  been  improperly  called  the  tunica 
erythroidea;  they  empty  themselves  with  the  greater  ease  along 
the  vasa  deferentia,  which  decrease  in  length  as  the  testicles 
rise,  and  which  participate  in  the  concussion  affecting  these 
organs. 

The  concussions  of  the  cremaster  on  the  testicle,  or  on 
the  vasa  deferentia,  promote,  in  so  important  a manner,  the 
secretion  and  excretion  of  the  semen,  that  this  little  muscle  is 
found  in  animals  whose  testicles  never  leave  the  abdomen,  but 
remain  within  that  cavity  on  the  sides  of  the  lumbar  region,  as 
was  observed  by  Hunter  in  the  hedge  hog  and  the  ram.  This 
fact  of  comparative  anatomy  shows,  that  the  cremaster  is  of  use, 
not  merely  in  suspending  the  testicles  as  its  name  indicates, 
since  in  the  animals  above  mentioned,  they  return  into  the  ab- 
domen towards  the  organ  on  which  they  are  to  act. 

When  irritation  is  carried  to  a certain  length,  it  acts  on  the 
vesiculae  seminales,  and  these  on  the  fluid  which  fills  their  ca- 
vity, and  they  expel  it  by  the  spasmodic  contraction  of  their 
membranous  parietes,  assisted,  in  this  excretion,  by  the  leva- 
tores  ani.  (CCI.)  The  prostate  gland  and  the  mucous  glands 
of  the  urethra  furnish  a viscid  substance,  calculated  to  promote 
the  evacuation  of  the  seminal  fluid,  which  is  emitted  in  jets, 
morfe  or  less  rapid. 

CCIV.  The  human  semen  is  never  emitted  in  a state  of  pu- 
rity, that  is,  such  as  it  is  prepared  by  the  testicles;  it  is  even 
conjectured,  that  the  mucous  fluid  of  the  vesiculae  seminales 
forms  the  greater  part  of  it.  It  is  this  mucus  which  eunuchs 
emit  in  considerable  quantity.  The  fluid  secreted  by  the  pros- 
tate gland  and  by  the  mucous  glands  of  the  urethra,  affect  it. 
likewise,  by  uniting  with  it. 


ON  GENERATION. 


523 


On  being  received  into  a vessel,  it  exhales  a peculiar  smell 
like  that  of  the  pollen  of  a great  number  of  plants,  for  example, 
of  the  chesnut  tree.  It  consists  of  two  parts,  the  one  thick  and 
in  clots,  while  the  other  is  viscid,  white  and  more  fluid.  The 
proportion  of  the  fluid  to  the  semi-concrete  part  is  greater,  in 
proportion  as  the  person  is  weaker,  and  as  the  emission  of  se- 
men is  more  frequently  repeated.  It  soon  liquefies,  by  losing 
part  of  its  weight,  which  always  exceeds  that  of  water,  in  which 
it  becomes  soluble,  though  it  was  not  so  at  first.  On  being  ana- 
lyzed by  M.  Vauquelin,  it  was  found  to  contain:  of  water  90 
centimes — of  animal  mucilage  6 — phosphate  of  lime  3 — soda  1. 
It  is  in  consequence  of  this  last  alkali,  that  it  is  enabled  to  turn 
syrup  of  violets  to  a green  colour.  The  animal  mucilage  is  not 
pure  albumine,  but  rather  a gelatinous  mucus,  on  which  the 
qualities  of  the  semen  appear  particularly  to  depend,  such  as  its 
insolubility  in  water,  its  odour  and  spontaneous  liquefaction. 

On  being  examined  with  the  microscope,  the  semen  is  seen 
to  contain  small  animalcules,  with  a rounded  head,  a tapering 
tail,  and  moving  with  rapidity.  Is  the  liquefaction  of  the  gluti- 
nous and  viscid  parts  of  the  semen,  owing  to  the  motion  of  these 
creatures?  These  microscopic  animalcules  are  to  be  detected  in 
the  semen,  only  at  the  period  of  puberty.  It  has  been  thought 
that  they  shunned  the  light;  authors  have  even  gone  the  length 
of  describing  their  ways  and  their  diseases.  The  imagination 
has  had  much  to  do  with  all  that  naturalists  have  fancied  they 
saw  in  these  creatures,  which  they  made  subservient  to  their  ex- 
planations of  the  mechanism  of  reproduction.  However,  it  must 
be  confessed,  that  in  all  the  animal  fluids  and  in  the  juices  of 
many  plants,  a certain  number  of  these  animalcules  may  be 
detected  by  means  of  the  microscope. 

A spasmodic  contraction  affects,  during  the  expulsion  of  the 
semen,  not  only  the  organs  of  generation,  but  the  whole  body 
participates  in  the  convulsive  state,  and  the  moment  of  emission 
is  accompanied  by  a commotion  of  all  its  parts;  so  that  it  should 
seem,  says  Bordeu,  that  in  that  instant,  nature  forgot  every 
other  function,  and  was  solely  engaged  in  collecting  her  strength 
and  directing  it  to  one  organ.  This  general  spasm,  this,  as  it 
were,  epileptic  convulsion,  is  followed  by  universal  depressionj 
this  physical  lassitude  is  attended  with  a sensation  of  sadness 


524 


ON  GENERATION. 


which  is  not  without  enjoyment.  Does  this  peculiar  sensation, 
which,  according  to  Lucretius,  mingles  grief  with  the  most 
lively  enjoyment  of  which  we  are  capable,  depend  on  the  fatigue 
of  the  organs;  or,  in  truth,  as  some  metaphysicians  have  ima- 
gined, on  the  confused  and  distant  notion  that  occurs  to  the 
soul,  of  its  own  dissolution? 

The  penis  does  not  enter  the  uterus,  though  the  semen  does. 
The  os  tincae  offers  too  small  a slit,  and  its  thick  edges  are  be- 
sides in  contact.  It  would  be  difficult  to  conceive  that  this  strait 
passage  should  admit  even  the  seminal  fluid,  if  it  were  not 
known,  that  in  the  moment  of  copulation,  the  uterus,  from  ir- 
ritation, draws  together,  and  inhales,  by  real  suction,  the  semen 
which  it  craves.  Plato  compared  this  organ  to  an  animal  living 
within  another  animal,  controlling  all  the  actions  of  the  living 
economy,  burning  to  sate  itself  with  the  liquor  of  the  male,  and 
digesting  it  to  form  a new  individual. 

The  great  thickness  of  the  cervix  of  the  uterus  has  given 
room  for  reasonable  doubt,  if  its  orifice  could  dilate  sufficiently 
to  admit  a fluid  of  the  consistency  of  semen.  Some,  therefore, 
have  thought  that  it  was  not  this  fluid  itself  that  penetrated  into 
the  cavity  of  the  uterus,  but  the  subtlest  of  its  parts,  the  most 
spiritualized,  a prolific  vapour,  to  which  they  have  given  the 
name  of  aura  seminalis;  but,  besides  that  the  semen  has  been 
found  in  the  uterus,  in  animals  opened  immediately  after  copu- 
lation, Spallanzani,  in  his  experiments  on  the  fecundation  of 
frogs,  of  salamanders,  and  toads,  perceived  that,  to  enable  the 
eggs  to  produce,  it  was  not  enough  to  expose  them  to  the  va- 
pour which  rises  from  the  seminal  fluid  of  the  male;  and  that 
nothing  was  effected,  unless  the  fluid  semen  actually  touched 
them,  though  in  ever  so  small  a quantity. 

It  has  been  said,  that  the  uterus  dilates  to  receive  the  semen, 
constricts  itself  to  retain  it,  and  that  this  spasmodic  contraction 
of  the  merus,  felt,  as  Galen  assures  us,  by  women,  who  pre- 
serve enough  sang-froid  to  make  observations  in  that  situation, 
was  the  most  undoubted  sign  that  could  be  had  of  the  success 
of  the  copulation.  It  is,  no  doubt,  to  insure  this  retention,  that 
it  is  customary  to  throw  cold  water  on  the  females  of  some  do- 
mestic animals,  when  they  go  too  eagerlv  to  the  male.  The 
spasms  of  the  skin,  occasioned  by  the  cold  striking  it,  affects  the 


ON  GENERATION.  525 

uterus,  and  hinders  the  flowing  back  of  the  semen  which  has 
been  thrown  into  its  cavity. 

It  has  also  seemed,  that  women  conceived  more  easily,  for  a 
little  time,  after  menstruation;  when  the  mouth  of  the  uterus  is 
less  exactly  closed  than  usual. 

The  seminal  fluid,  thrown  into  the  cavity  of  the  uterus,  pas- 
ses along  the  fallopian  tubes  to  the  ovaria.  It  does  not  diflPuse 
itself  in  the  cavity  of  the  abdomen,  because  the  membranous 
duct  seizes  the  ovarium,  which  corresponds  to  it,  grasps  it  closely, 
and  establishes  an  uninterrupted  canal,  from  this  organ  to  the 
uterus.  The  ovarium,  bedewed  by  the  semen,  irritated  by  its 
contact,  lets  a fluid  escape,  or  perhaps  a little  ovum,  which 
passes  into  the  uterus,  the  same  way  that  the  semen  reached 
itself.*  All  that  remains  to  be  said,  concerning  the  mechanism 

* Tlie  account  here  given  of  the  fecundation  of  the  ovum,  seems  to  us 
exceeding  erroneous,  and  as  this  is  a point  of  some  interest,  we  will  not 
too  hastily  dismiss  it. 

It  is  our  intention,  first,  to  show  that  the  semen  does  not  enter  the  cavity 
of  the  uterus,  much  less  that  it  reaches  the  ovary.  Those  who  differ  from 
us  on  this  subject,  have  mostly  insisted  that  the  semen  is  thrown  into  the 
uterus,  by  injection  from  the  penis.  True  it  is,  that  some  other  modes  have 
been  suggested,  but  they  are  really  so  ridiculous,  as  to  be  wholly  unworthy 
of  criticism. 

That  tlie  male  organ  is  endowed  with  a considerable  projectile  power, 
cannot  be  denied.  It  is  very  conspicuously  evinced,  by  the  impetus  with 
which  the  urine  is  discharged.  When  engaged,  however,  in  the  act  of  coi- 
tion, its  capacity  in  this  respect,  is  greatly  diminished,  or  wholly  suspended 
by  the  firmness  with  which  it  is  embraced.  Grasped  by  the  vagina,  its  ejacu- 
latory muscles  are  crippled  in  their  energies,  and  become  passive.  We  see 
too,  in  the  spissltude  and  tenacity  of  the  semen,  an  additional  cause  of  re- 
sistance. So  heavy  and  glutinous  a fluid,  it  is  plain,  cannot  be  thrown  to  any 
distance.  There  is  moreover  a structure  in  the  vagina,  co-operating  to  the 
same  end.  The  rugae  of  its  inner  surface  seem,  indeed,  evidently  designed  as 
so  many  barriers,  to  arrest  the  progress  of  the  semen. 

But  admitting,  that  by  an  unusually  vigorous  impulse  it  were  projected  as 
far  as  the  uterus,  how  could  it  enter  into  the  cavity  of  that  viscusi  Let  it  be 
recollected  that  the  os  tincae,  at  least,  in  the  virgin  state,  is  nearly  as  small 
as  the  opening  of  the  urethra  in  the  male,  and  is  not  placed  in  the  im- 
mediate  a.vis  of  the  vagina,  but  is  inclined  more  or  less  to  the  one  or  the 
other  side,  or  towards  the  sacrum.  The  apertures  of  the  two  organs,  there- 
fore, are  not  in  apposition.  But  this  is  not  all.  The  os  tines  is  for  the  most 
part  filled  with  a thick  glutinous  matter,  capable  of  considerable  resistance. 
Wher«  it  is  wanting,  as  is  generally  the  case  in  the  virgin  uterus,  the  hard, 


526 


ON  GENERATION. 


of  generation,  must  not  he  delivered  as  real,  but  merely  as  pro- 
bable, such  is  the  darkness  with  which  nature  has  chosen  to 
envelop  this  great  mystery  of  the  living  economy. 

unyielding’  lips  of  the  tincae  are  so  closel}'  approximated  as  to  be  nearly 
closed. 

Nor  are  these  the  only  obstacles  to  the  passage  of  the  semen.  The  canal 
leading  through  the  neck  and  body  of  the  uterus,  is,  in  the  unimpregnated 
state  of  the  organ,  probably  not  larger  than  a common  size  probe.  That  por- 
tion of  the  canal  called  the  straight,  is  still  more  contracted.  Besides,  along 
the  whole  course  of  the  canal,  there  are  striae,  or  wrinkles,  and  between 
which,  glands,  secreting  mucus  obviously  calculated  for  the  purpose  of  ad- 
ditional obstruction.  Even  the  proper  cavity  of  the  uterus  itself,  is  so  ex- 
tremely shallow  that  its  two  surfaces  are  nearly  in  contact 

Such  are  the  impediments  incident  to  a perfectly  natural,  and  healthy  con- 
dition of  the  parts.  To  these  ma)'  be  added  others  resulting  from  morbid 
derangements,  or  congenital  deformities, , and  which  are  found  to  exist  as 
well  in  the  male  as  the  female  organs. 

1.  The  penis  has  its  power  of  ejecting  the  semen,  destroyed  or  abridged 
by  truncation,  by  strictures,  by  anomalous  openings  along  the  course  of  the 
urethra,  or  by  debility  and  relaxation. 

2.  The  vagina  is  obstructed  or  shut  up  by  cohesion  of  its  sides,  by  mem- 
branes of  adventitious  growth,  or  by  tumors. 

3.  The  os  tincse  is  sometimes  discovered  impervious,  either  from  original, 
imperfection,  or  by  the  process  of  inflammation,  and  is  occasionally  render- 
ed utterly  inaccessible  to  the  semen,  by  the  obliquities,  retroversions,  or 
prolapsions  of  the  womb.* 

These  facts  very  clearly  demonstrate,  that  conception  can  take  place, 
though  the  semen  may  be  deposited  merely  within  the  vulva,  and  seem  al- 
most to  warrant  the  conclusion,  that  it  never  does,  as  a natural  event,  reach 
the  cavity  of  the  uterus.  Lest,  however,  they  may  not  appear  to  others  in  the 
same  strong  light,  in  which  they  present  themselves  to  us,  we  will  bring  to 
their  aid  some  further  evidence. 

Experiments  have  been  resorted  to  in  order  to  decide  this  point.  They 
have  been  made  by  Harvey,  De  Graaf,  Luenhoeck,  Haller,  and  Haighton. 
Different  animals  were  the  subjects  of  these  experiments.  The  doe,  the  cow, 
the  ass,  the  ewe,  the  bitch,  the  rabbit,  were  all  inspected  immediately,  or  at 
remoter  periods,  after  conne.xion  with  the  male,  and  never  except  in  one  in- 
stance, could  the  semen  be  traced  beyond  the  vagina.  By  Haller  it  is  stated, 
that  he  once  detected  the  semen  in  the  uterus  of  a sheep  forty-five  minutes 
post  coitu.  But  this  is  a solitary  exception,  to  the  numerous  observations  both 
of  himself  and  others,  and  which  can  claim  litde  consideration,  especially 


* Each  of  the  above  positions  is  supported  by  cases  to  be  found  in  the 
writings  of  Harvey,  Morgagni,  Hildanus,  Ruysh,  Mauriceau,  Simpson, 
Guillemeau,  Haller,  and  in  the  periodical  journals. 


ON  GENERATION. 


527 

After  distinguishing  the  true  from  the  probable,  an  indispen- 
sable duty  in  every  science  of  facts  and  observations  like  phy- 
siology, I shall  proceed  to  state  the  hypothesis  which  appears 

when  it  is  known,  that  such  a result  was  essentially  necessary  to  the  main- 
tenance of  a favourite  hypothesis. 

As  auxiliary  to  this  single  experiment  of  Haller,  it  is,  however,  urged  that 
Morgagni  saw  the  semen  in  the  uterus,  and  Ruysh  in  the  fallopian  tube  of 
the  human  species.  Without  impeaching  the  veracity  of  either  of  these 
illustrious  men,  we  may  be  permitted  to  remark,  that  their  observations 
have  never  been  confirmed,  and  that  under  the  circumstances  in  which 
they  were  made,  it  is  reduced  almost  to  a moral  certainty  that  they  mis- 
took for  semen  what  was  in  reality  the  mucus  of  the  parts.  But,  conceding 
to  tliese  alleged  facts  all  that  can  reasonably  be  required,  what  do  they 
amount  to?  Contrasted  with  the  vast  mass  of  counter  evidence,  they  dwin- 
dle into  insignificance  and  will  not  weigh  as  the  dust  in  the  scale. 

It  appearing,  therefore,  that  the  semen  does  not  enter  the  uterus,  it  be- 
comes superfluous  to  inquire  respecting  the  practicability  of  its  conveyance 
by  the  fallopian  tubes.  The  latter  problem  is  merged  in  the  former.  But  to 
silence  all  cavils,  we  will  give  the  question  a cursory  examination. 

That  the  fallopian  tubes  are  not  subservient  to  this  purpose,  is  very  dis- 
tinctly indicated  by  the  peculiarity  of  their  structure.  Commencing  with 
an  aperture  so  very  minute,  as  hardly  to  admit  a common  bristle,  the  canal 
gradually  enlarges,  and  finally  terminates  in  a wide  and  patulous  mouth. 
Now,  were  they  destined  to  convey  from,  instead  of  to  the  uterus,  would 
not  the  construction  be  directly  the  reverse  of  what  it  is?  We  know  that 
they  conduct  the  product  of  the  ovary  to  the  womb,  and  we  see  that  the 
extremity  is  adapted  to  this  office.  It  is  almost  as  well  ascertained  that  they 
convey  nothing  from  the  uterus,  and  the  orifice  is  fashioned  accordingly. 

By  assigning  to  the  tube  this  function,  we  moreover  invest  it  with  the 
power  of  a two-fold  action,  precisely  opposite,  of  which  there  is  no  analogy 
in  the  animal  economy.  The  inverted  peristaltic  motion  of  the  intestines, 
comes  nearest  to  an  example,  but  it  will  not  hold.  The  cases  are  not  parallel, 
the  action  of  the  intestine  being  preternatural,  the  effect  of  violence  and  dis- 
ease. It  is  useless,  however,  to  protract  this  discussion,  as  we  have  proof  at 
hand  which  is  absolutely  conclusive.  By  the  experiments  of  Mr.  Haighton, 
it  is  ascertained  that  the  tubes  do  not  change  their  position  to  grasp  the 
matured  vesicle  till  the  whole  process  of  conception  is  consummated  in  the 
ovary. 

“ 1 found,”  says  this  eminent  physiologist,  “ from  a series  of  observations 
made  on  different  rabbits,  at  every  hour  between  the  1st  and  9th,  that  the 
fimbrite  remained  nearly  in  their  usual  situation,  and  the  only  difference  I 
found  in  the  last  hour,  was  a greater  turgescency  of  vessels,  as  if  preparatory 
to  some  important  action.  I desisted  from  this  inquiry  at  the  9th  hour,  because 
the  ovaries  bore  evident  marks  of  impregnation,  and  there  appeared  to  be 
no  action  in  the  tubes,  by  which  the  semen  could  be  conveyed  to  them.” 

Convinced 


ON  GENERATION. 


528 

to  me  the  likeliest  on  the  manner  in  which  the  two  sexes  concur 
in  the  production  of  the  new  being. 

CCV.  The  fcEtuses  pre-exist  in  the  ovaria  of  the  females, 
not  that  they  are  there  since  the  creation  of  the  world,  as  Bon- 
net believed,  and  all  who  embraced  the  doctrine  of  that  meta- 
physical naturalist:  but  the  ovaria  containing  his  germs  are 
formed  by  the  proper  action  of  the  ovarium  which  secretes 
them,  a fresh  proof  that  all  the  phenomena  of  organized  bodies, 
whether  for  the  preservation  of  the  species  or  of  the  individual, 
are  effected  in  the  way  of  secretions.  This  ovum  produced  by 
the  elaboration  of  the  blood  which  the  spermatic  vessels  carry 
to  the  ovaria,  contains  the  lineaments  of  the  new  being:  but  it 
is  only  the  sketch,  or  carcass  of  it,  if  this  may  be  applied  to 
what  has  yet  not  lived.  The  seminal  fluid  must  bring  it  out  of 
this  state  of  inactivity,  and  with  something  of  an  electrical  power 
waken  it  into  life.  The  eggs  laid  by  a maiden  hen,  will  never 
hatch,  though  there  are  in  them  the  rudiments  of  the  chick. 
The  eggs  of  a frog  that  has  been  kept  apart  from  the  male, 
during  the  whole  time  of  spawning,  putrefy  in  the  vessel  of 
water  they  are  kept  in;  if  the  male  on  the  contrary,  sprinkled 
them  with  his  semen,  as  they  quitted  her,  they  will  speedily  show 
some  development  of  life.  Their  putrefaction  may  be  prevent- 
ed, and  themselves  animated,  by  shedding  on  them  the  sper- 

Convinced  that  the  hypothesis  in  its  primitive  shape  was  no  longjer  tenable, 
some  of  the  advocates  of  impregnation  by  contact,  have  contended  that  it  is 
effected  by  the  emission  of  subtle  exhalation  from  the  semen,  termed  aura 
seniinalis,  and  which  is  transmitted  through  the  tubes  to  the  ovary.  But  here 
they  are  again  met  by  the  whole  body  of  facts,  and  chain  of  reasoning-  which 
drove  them  from  their  original  position.  It  has  indeed  been  said,  and  with  no 
want  of  plausibility,  that  the  volatile  vapours  from  the  semen  might  penet  ate 
through  obstructions  which  would  resist  the  semen  itself  Be  it  so:  in  many 
instances,  it  might  happen  undoubtedly.  But  still,  how  can  the  cases  formerly 
referred  to,  be  got  over,  where  from  organic  dei-angement,  the  passages  were 
so  entirely  occluded,  as  to  be  impervious  even  to  air! 

Nor  are  these  the  only  difficulties  that  stand  in  the  way  of  this  amended 
hypothesis.  We  are  not  disposed,  however,  to  enter  at  present  into  any  fur- 
ther detail.  Before  we  engage  in  a lengthened  investigation  of  this  sort,  we 
require  it  to  be  shown  that  the  aura  seminalis  has  the  property  of  fecunda- 
tion. As  yet,  no  such  proof  has  been  exhibited.  The  experiments  of  Spallan- 
zani, and  Hunter,  the  only  ones  which  have  been  made  on  the  subject,  proa-e 
indeed  quite  the  contrar\‘. — Ed. 


OJP  GENERATION,  529 

matic  fluid,  obtained  by  the  process  employed  by  Spallanzani, 
in  his  admirable  experiments  on  artificial  impregnation. 

It  is  especially  to  the  labours  of  this  able  observer,  that  we 
owe  what  has  been  unveiled  of  the  mystery  of  generation,  and 
of  the  part  which  each  sex  bears  in  this  function.  It  is  almost 
proved,  that  the  male  co-operates  in  it  only  by  supplying  the 
vivifying  principle  that  must  animate  the  individuals,  of  which 
the  female  furnishes  the  germs;  that  thus  his  part  is  the  least 
essential.  It  is  not  so  difficult  as  may  be  imagined,  to  explain 
upon  this  system  the  striking  resemblances  which  are  frequently 
seen  between  fathers  and  sons.  The  imperceptible  embryo  has, 
at  most,  the  consistency  of  a slightly  viscous  glue.  Such  a body 
must  be  exceedingly  impressible,  and  the  semen  of  the  male, 
applied  to  its  surface,  must  impress  on  it  powerful  modifications. 
The  action  of  the  fluid  on  this  yet  tender  embryo  must  be  like 
that  of  a seal  which  stamps  on  the  soft  wax  its  own  image.  The 
impression  is  the  deeper,  the  resemblance  the  more  striking, 
according  to  the  spirit  and  energy  with  which  the  male  perform- 
ed the  act  of  reproduction. 

The  seminal  fluid  may  not  merely  act  on  the  surface  of  the 
gelatinous  and  nearly  liquid  germ,  and  modify  it  externally, 
but  it  may  penetrate  so  soft  a substance,  and  impress  on  it  in- 
ward changes.  It  is  thus  that  we  are  able  to  explain,  not  only 
hereditary  likeness,  but  also  hereditary  diseases.  Nevertheless, 
it  does  appear,  that  the  interior  parts  are  derived  chiefly  from 
the  female,  while  the  outward  parts  are  especially  influenced  by 
the  male;  for,  when  two  animals  of  different  species  copulate, 
the  mule  resembles  the  sire  outwardly,  and  the  dam  within. 
It  is  difficult  to  show  good  reason  for  the  want  of  the  genera- 
tive faculty  in  mules.  Why  are  their  sexual  parts,  so  well  deve- 
loped, altogether  barren?— -What  secret  defect  frustrates  their 
action?  And  why  do  certain  mules,  among  birds,  propagate; 
and  in  the  same  manner,  hybrid  plants,  which  are  real  mules, 
and  not  quadrupeds? 

The  impregnation  of  the  ovum  is  effected  in  the  ovarium 
itself,  to  which  the  semen  is  conveyed,  as  has  been  said.  The 
ovum,  stirred  by  the  action  of  the  semen,  and  of  the  fallopian 
tube,  detaches  itself  from  the  organ  which  has  produced  it,  and 
descends  into  the  uterus,  by  the  peristaltic  contractions  of  the 

3 X 


ON  GENERATION. 


530  , 

fallopian  tube.  This  canal  is  susceptible  of  a retrograde  motion. 
It  may  be  conceived,  by  considering  that  having  stretched  itself 
by  a real  erection  to  convey  the  semen  to  the  ovarium,  is  must, 
an  its  return  upon  itself,  cause  a flow  of  the  fluid  its  cavity  con- 
tains, in  a completely  inverted  direction.  This  retrograde  mo- 
tion, as  Nisbet  observes,  is  assisted  by  a sort  of  collapse  suc- 
ceeding the  excitation  which  coition  had  produced:  for,  the 
experiments  of  Darwin  prove  that  the  weakness  of  the  ves- 
sels is  the  cause  of  this  mode  of  action  in  their  parietes.  Spungy 
as  the'  urethra  of  man,  the  fallopian  tube  brings  back  the  ovum, 
from  the  ovarium  to  the  uterus.  The  extra-uterine  foetations 
afford  the  proof,  that  matters  are  carried  on  in  the  manner  we 
have  stated.  Since  foetuses  have  been  found  developed  in  the 
ovarium,  in  the  fallopian  tube,  and  even  in  the  cavity  of  the 
abdomen,  when  the  detached  ovum  has  escaped  from  the  grasp 
of  the  corpus  limbriatum,*  one  must  admit  that  it  follows  the 
course  which  has  been  described. 

The  ovaria,  like  the  testicles,  swell  and  enlarge  at  the  time 
of  puberty.  They  shrink,  and  wither  in  some  sort,  when  the 

* In  extra-uterine  abdominal  conceptions,  the  ovum  which  the  tube  could 
not  hold,  or  seize,  rolls  into  the  hypogastric  region,  and  there  adheres  to 
some  point  of  the  peritoneum.  It  is  found  attached  to  the  mesentery,  to  the 
colon,  to  the  rectum,  to  the  external  part  of  the  uterus,  growing  there,  and 
developed,  by  the  vascular  communication  w’hich  takes  place  at  the  adhe- 
sion: but  the  vessels  of  the  peritoneum  are  insufficient  for  the  entire  deve- 
lopment of  the  fcEtus,  which  dies,  for  want  of  nourishment,  in  the  first  months 
of  pregnancy.  The  adhesion  of  the  ovum  to  the  peritoneum,  is  easily  account- 
ed for,  by  the  irritation  it  occasions:  it  may  be  considered  as  a foreign  body, 
determining,  by  its  presence,  inflammation  of  the  membrane  with  which  it 
lies  in  contact,  and  uniting  with  it,  because  it  brings  to  this  act  its  own  share 
of  vitality.  It  is  really  a union  of  two  living  parts,  not  unlike  to  that  which 
takes  place  betw'een  U>e  bleeding  lips  of  a wound,  between  the  pleura  pulmo- 
nalis,  and  the  pleura  costalis,  kc. 

But  as  the  serous  membranes  contain,  in  their  tissue,  capillaries  so  fine, 
that  when  in  a healthy  state,  the  blood  does  not  show  its  colour  in  them, 
their  vessels  never  develope  themselves  sufficiently  to  transmit  to  the  ovum, 
which  has  adhered  to  them,  a due  supply  of  this  fluid.  The  mucous  mem- 
branes receiving  more  blood,  are  able  to  supply  more:  but  the  placenta  never 
adheres  to  them  in  extra-uterine  conception.  The  membrane  which  lines  the 
tube  belongs,  in  fact,  as  much  to  the  serous  as  to  the  mucous  membranes;  it 
establishes,  as  is  well  known,  the  only  pomt  of  communication  there  is  be- 
tween the  two  kinds  of  membranes. 


0^'^  GENERATION. 


S31 


woman  is  no  longer  fit  for  conception.  On  examination,  a few 
days  after  conception,  one  of  the  ovaria,  larger  than  the  other, 
shows  a little  yellowish  vesicle,  which  dries  up  in  the  course  of 
pregnancy,  so  that,  towards  the  end,  there  remains  nothing  in 
its  place,  but  a very  small  cicatrix.  Is  this  vesicle  the  outermost 
covering  of  the  ovum,  in  which  the  germ  is  enclosed,  and  which 
is  torn  to  allow  its  escape?  The  observations  of  Haller  prove 
that  the  corpus  luteum  is  formed  by  the  remains  of  a vesicle 
that  has  burst  at  the  moment  of  conception,  and  allowed  the 
fluid  it  contained  to  escape.  In  a ewe  opened  a few  minutes 
after  coition,  you  may  see,  in  one  of  the  ovaria,  a vesicle  larger 
than  the  others,  torn  with  a little  wound,  of  which  the  lips  are 
still  bloody.  Inflammation  comes  on  in  the  torn  coats  of  the 
small  vesicle,  fleshy  granulations  appear,  then  sink,  and  a scar 
shows  the  place  where  it  had  been.  The  number  of  these  cica- 
trices  is  proportioned  to  that  of  the  fetuses.  It  is  not  known 
how  long  the  germ  detached  from  the  ovarium  remains  within 
the  fallopian  tube,  before  it  reaches  the  cavity  of  the  uterus. 
Valisnieri  and  Haller  had  never  been  able  to  perceive  it  dis- 
tinctly in  this  viscus,  before  the  seventeenth  day. 

The  obstruction  of  the  tubes  may,  as  well  as  the  defect  or 
diseased  affection  of  the  ovaria,  cause  barrenness.  Morgagni 
speaks,  on  this  head,  of  certain  courtezans  in  whom  the  tubes 
were  entirely  obliterated  by  the  thickening  of  their  parietes;the 
consequence,  evidently,  of  the  habitual  orgasm  in  which  they 
had  been  kept,  by  too  frequent  excitation.  The  structure  of 
these  parietes  must  make  obstructions  of  the  fallopian  tubes 
very  easy.  Their  tissue  is  spungy,  vascular,  and  seems  suscep- 
tible of  erection,  like  the  corpus  cavernosum  of  the  penis  and 
of  the  clitoris.  Their  internal  coat  (the  point  of  union  between 
the  serous  membrane  which  lines  the  abdomen,  and  the  rau- 
cous membrane,  within  the  uterus)  partakes  in  the  inflammation 
of  both.  I have  often  been  consulted  by  young  women  on  the 
cause  of  their  sterility;  by  a close  investigation  of  the  causes 
from  which  it  might  have  arisen^  I have  always  found  that  they 
had  had,  at  different  periods  of  life,  inflammation  of  the  lower 
part  of  the  abdomen.  A.  young  woman,  after  obstinate  suppres- 
sion of  the  menses,  exhibited  all  the  symptoms  of  inflammation 
of  the  peritoneum:  a year  afterwards  she  married,  but  never 


ON  GENERATION. 


532 

became  pregnant.  A woman  recovered  from  puerperal  fever 
ensuing  upon  a very  difficult  first  labour;  from  that  time,  with 
all  the  appearances  of  the  stoutest  health,  she  has  never  been 
again  a mother. 

Do  the  two  testicles  and  the  two  ovaria,  contain  the  separate 
germs  of  males  and  females?  Are  these,  as  has  been  guessed, 
contained  in  the  left  ovarium,  and  males  in  the  right?  and  may 
we  procreate  sexes  at  pleasure,  by  varying  the  attitude  of  co- 
pulation? This  old  opinion,  lately  revived,  besides  wanting  all 
foundation,  is  formally  confuted  by  facts:  nothing  is  more  com- 
mon than  to  see  men  who  have,  from  some  accident,  lost  a tes- 
ticle, procreating  sexes  indifferently.  Women,  with  an  ovarium 
deficient,  or  the  fallopian  tube  obliterated  on  one  side,  have  pro- 
duced both  boys  and  girls.  Dr.  Jadelot  has  presented  to  the 
Society  of  the  School  of  Medicine  in  Paris,  a uterus,  wanting 
the  right  tube  and  ovarium:  and  nothing  indicated  that  they  had 
ever  existed.  On  inquiry  concerning  this  woman,  it  appeared 
that  she  had  been  delivered  of  a boy  and  two  girls:  Haller 
quotes  similar  cases.  The  cause,  then,  which  determines  the 
sex,  altogether  eludes  our  investigation.  Does  that  one  of  the 
two,  who  exerts  most  energy  in  the  act  of  coition,  impress  its 
sex  on  the  offspring?  I cannot  tell;  but  I think  I have  observed 
that  the  marriage  of  young  people,  where  both  are  glowing  with 
love  and  youth,  most  frequently  produces  daughters,  whilst 
boys  are  ordinarily  the  consequence  of  the  union  of  a middle 
aged,  or  elderly  man,  with  a younger  woman. 

CCVI.  Sy sterns  on  generation.  The  antique  system  of  the 
mixture  of  the  semen  in  the  cavity  of  the  uterus,  set  forth  in  the 
writings  of  Hippocrates  and  Galen,  is  still  that  of  many  physio- 
logists. In  this  system,  the  mixed  fluids  may  be  considered  as 
an  extract  from  all  parts  of  the  body’,  male  or  female.  A gene- 
rative faculty*  disposes  them  suitably  for  the  formation  of  the 
new  individual.  Buffon  has  further  particularized  the  facts 
which  this  hypothesis  requires,  and  displayed  its  improbability. 
Eachpart,  he  says,  furnishes  molecules,  which  he  calls  organic, 

* All  that  Blumenbach  has  said,  on  the  force  of  formation,  {nisus  foi'mati- 
vtis)  applies  to  this  g-enerative  faculty;  it  is  only  a new  name  given  to  an  old 
idea. 


ON  GENERATION. 


533 

and  these  molecules,  coming  from  the  eyes,  the  ears,  &c.  of  the 
man  and  the  woman,  arrange  themselves  round  an  interna! 
mould,  of  which  he  admits  the  existence,  which  mould  forms 
the  basis  of  the  edifice,  and  comes  from  the  male  probably,  if  it 
be  a boy,  from  the  female,  if  a girl.  Reason  rejects  a theory 
which  gives  no  explanation  of  the  production  of  the  placenta, 
and  of  the  membranes  covering  the  foetus;  it  is  moreover  di- 
rectly disproved  by  the  good  conformation  of  children,  born  of 
parents,  who  not  happening  to  have  certain  organs  and  limbs, 
could  not  certainly  supply  the  proper  molecules  for  their  forma- 
tion in  the  child. 

The  system  of  the  ovarists,  which  at  this  time  stands  highest 
in  favour,  numbers  amongst  Its  supporters,  Harvey,  Stenon, 
Malpighi,  Valisnieri,  Duhamel,  Nuck,  Littre,  Swammerdam, 
Haller,  Spallanzani,  Bonnet,  &c.  These  admit  the  distinction 
of  animals  into  oviparous  and  viviparous,  in  this  sense  only, 
that  these  last  hatch  within,  and  break  their  shell  before  they 
are  brought  forth.  Lastly,  Lewenhoek,  Hartsoeker,  Boer- 
haave,  Mery,  Werheyen,  Cowper,  &c.  have  added  to  the 
opinion  of  the  ovarists,  that  the  seed  of  the  male  contains  a 
multitude  of  spermatic  animalcules,  all  capable  of  becoming,  by 
development,  beings  similar  to  their  father.  These  animalcules 
push  forwards,  along  the  tubes,  upon  the  ovaria:  there  a gene- 
ral engagement  takes  place,  in  which  all  are  slain,  save  only 
one,  who,  master  of  the  field  of  battle,  finds  the  triumph  of  his 
victory  within  the  ovum  that  has  been  prepared  for  him.  This 
system,  which  is  not  the  most  probable  in  the  world,  assigns  to 
the  male  the  greater  part  in  the  work  of  generation,  since  the 
female  is  made  to  furnish  merely  the  covering  of  fetus. 

It  would  be  to  no  purpose  to  unfold,  more  at  large,  opinions 
hazarded  on  a subject  so  obscure.  What  I have  said  is  enough 
to  show  that  those  parts  of  nature  which  most  obstinately  elude 
our  curiosity  and  afford  most  scope  to  our  imagination,  are 
those  which  men  believe  they  know  the  best,  and  on  which 
they  speak  with  most  confidence  and  prolixity: — so  true  is  it, 
as  Condillac  has  observed,  that  we  have  never  so  much  to  say, 
as  when  we  set  out  from  false  principles.* 

• Numerous  as  are  the  theories  which  have  been  advanced  on  the  subject 
of  generation,  they  may  all,  as  mere  varieties,  (or  at  least  such  as  are 


ON  GENERATION. 


S34 

CCVII.  Of  gestation.  From  the  moment  of  conception,  there 
begins  in  woman,  both  in  the  motion  of  the  solids,  and  the  com- 
position of  the  fluids,  a remarkable  alteration.  The  change  that 
has  taken  place  shows  itself  in  all  her  functions;  she  exhales  a 

worthy  of  attention),  be  very  properly  reduced  under  two  leading  heads  or 
general  divisions. 

1.  Doctrine  of  Palengenisis. 

2.  Doctrine  of  Epigenisis. 

The  first  of  these  doctrines  supposes  the  pre-existence  of  germs.  It  is  of 
great  antiquity,  and  in  its  descent  to  us  has  undergone  some  slight  modifi- 
cations. By  most  of  the  early  philosophers  it  was  taught,  “ That  these 
germs  created  with  the  beginning  of  things,  were  scattered  throughout  the 
world,  but  ultimately  meeting  with  appropriate  genital  organs,  effected  a 
lodgment  therein,  and  became  fit  for  development.” 

As  soon,  however,  as  the  moderns  entered  into  speculations  of  this  nature, 
the  hypothesis  received  a correction  which,  in  part,  divested  it  of  its  absur- 
dity. Denying  that  these  germs  wandered  about  “ in  quest  of  an  habitation 
and  a home,”  it  was  now,  on  the  contrary,  maintained,  “ That  all  of  the 
same  species,  were  ah  initio  neatly  incased,  one  within  another,  so  that  the 
first  parent,  animal  and  vegetable,  contained  the  germs  of  each  succeeding 
generation,  and  which  to  be  evolved  required  only  the  seminal  impulse  of  the 
male.” 

This  doctrine  of  evolution  had  been  hardly  revived,  when  two  sects  arose, 
who  urged  their  respective  opinions  with  all  the  zeal,  all  the  ardour,  and  all 
the  pertinacity  of  party  controversialists.  They  differed,  however,  only  on 
a single  point.  By  the  one  side  it  was  maintained,  that  the  germs  w'ere  fur- 
nished by  the  female,  and  by  the  other  that  they  proceeded  from  the  male. 

The  former  of  these  opinions  was  brought  into  repute  by  Fabricius  ab 
Aquapendente,  so  called  from  the  place  of  his  nativity.  Having  ascertained, 
as  he  thought,  by  a series  of  experiments  on  the  egg,  that  it  contained  a pre- 
e.xisting  embryon,  he,  with  a numerous  train  of  disciples,  pushed  their  inves- 
tigations, and  finally  detected,  or  pretended  to  detect,  ova  also  in  the  vivi- 
parous animals. 

Enamoured  of  this  boasted  discovery,  the  celebrated  Har%-ey  became  one 
of  the  warmest  and  most  strenuous  supporters  of  the  hypothesis  to  which  it 
led. 

“ Omnia  ex  ova.” 

This  brief  aphorism,  which  escaped  from  him  in  the  enthusiasm  of  his  de- 
votion, sufficiently  marks  his  impressions  on  the  subject.  The  only  dis- 
tinction, indeed,  which  he  admits  in  the  generative  process  of  the  two 
classes  of  animals,  is,  “ That  in  the  viviparous,  the  foetus  begins  to  exist, 
increases,  and  completes  its  growth  in  the  uterus;  whereas,  in  the  ovipa- 
rous, the  embryo  exists  in  the  egg  in  the  body  of  the  hen,  but  does  not  be- 
come a fcBtus  till  expelled,  and  is  hatched  into  life  by  incubation.” 

The  ovular  doctrine  was  first  arraigned  by  Luenhoeck,  who  made  the  pre- 
tended discovery  of  the  spermatic  animalcules  in  the  male  seed.  By  him  and 


ON  GENERATION. 


535 

peculiar  odour;  the  child  she  suckles  refuses  the  breast,  or  takes 
it  with  reluctance,  and  soon  falls  away,  if  left  in  the  hands  of 
such  a nurse. 

Nature,  occupied  over  her  work,  seems  to  forget  every  thing 

his  followers,  the  existence  of  ova  in  viviparous  animals  was  speedily  and 
satisfactorily  confuted.  They  demonstrated  to  entire  conviction,  that  what 
had  been  taken  for  true  ova  were  the  mere  vesicles  of  the  ovary,  wliich 
have  no  resemblance  to  an  egg',  being  merely  cups  or  reservoirs  of  a fluid, 
which  after  fecundation  is  discharged  and  conveyed  by  the  fallopian  tube 
to  the  cavity  of  the  uterus.  They  further  proved,  that  previously  to  im- 
pregnation nothing  like  a germ  could  be  found  even  in  the  real  egg,  but  that 
there  is  placed  on  the  vitellus,  a small  vesicle,  the  cicatricula,  containing  a 
fluid  of  the  same  nature,  and  destined  for  the  same  end  as  that  in  the  vesicle 
of  the  ovary.  The  only  difference,  therefore,  in  this  respect,  between  the 
egg  and  ovary,  according  to  this  sect,  is,  that  the  former  has  a single, 
while  the  latterhas  a cluster  of  vesicles. 

By  this  doctrine  of  spermatic  worms,  which  completely  usurped  the  place 
of  the  ovular  doctrine,  and  which  acquired  for  a time  an  undisputed  ascen- 
dency in  the  medical  and  philosophical  schools,  it  was  affirmed,  that  these 
seminal  vermiculi  are  living  miniatures  of  the  animal  from  which  they  are 
derived,  exacting  only  from  the  female  a matrix  for  nourishment,  evolution 
and  growth'. 

Though  the  ovular  doctrine  was  thus  subverted  by  Luenhoeck  and  his 
auxiliaries,  it  after  a while  again  revived,  under  the  auspices  of  Haller,  so 
far  at  least,  as  to  suppose  the  pre-existence  of  a germ  in  the  female,  and 
soon  received  the  distinguished  support  of  Bonnet,  Spallanzani,  Hunter,  &c. 
Being  restored  in  a more  enlightened  age,  it  of  course  was  stripped  of  most 
of  those  extravagancies  which  had  before  detracted  so  much  from  its  merit. 
Agreeing  in  the  fundamental  principle  of  the  doctrine,  these  physiologists 
entertained  some  difference  of  opinion  as  to  the  origin,  the  existence  and  de- 
velopment of  the  germs.  They  all,  however,  maintained,  “ that  the  germ, 
as  the  exact  miniature  of  the  animal  or  vegetable  to  which  it  belongs,  exists 
in  the  female  prior  to  fecundation,  requiring  only  the  stimulus  of  the  male 
seed  to  excite  it  into  life,”  &c.  &c. 

By  thus  narrowing  the  definition  of  the  doctrine,  they  presented  it  in  a 
guise  exceedingly  alluring,  and  rested  its  vindication  on  a collection  of  ex- 
periments and  observations,  in  appearance,  the  most  definite  and  conclusive. 
These,  however,  on  a closer  examination,  exhibit  a very  different  aspect,  so 
much  so  indeed  that  a large  number  of  distinguished  physiologists  have  been 
induced,  upon  the  most  diligent  scrutinies,  to  question  altogether  the  pre- 
existence of  germs.  It  would  be  wholly  inconsistent  with  our  limits  to  detail 
the  arguments  and  reasonings  which  have  been  employed  by  the  adverse 
parties  in  this  interesting  controversy.  We  proceed  next,  therefore,  to  the 
doctrine  of  Epigenlsis. 

Discarding,  as  we  have  already  hinted,  the  notion  of  the  pre-existence  of 
germs,  it  presumes  that  “ the  prepared,  but  at  the  same  time  unorganized 


536 


ON  GENERATION, 


else,  to  bring  it  to  perfection.  It  has  been  observed,  that  in 
times  of  contagious  diseases,  even  where  the  plague  raged, 
pregnant  women  were  least  exposed  to  infection;  bnt,  at  the 
same  time,  when  they  are  seized  with  affections,  which  in 
other  persons  or  at  another  season,  would  be  without  danger, 
they  sink  under  them,  because  their  diseases,  though  at  first 
very  slight,  easily  put  on  a malignant  character.  The  progress 
of  mortal  diseases  is  retarded:  a phthisical  woman,  and  who 
has  only  a few  months  to  live,  shall  prolong  her  life  through 
the  whole  term  of  gestation.  The  consolidation  of  fractures  is 
nothing  slower,  though  Fabricius  Hildanus  pretends  that  the 
state  of  pregnancy  puts  a complete  stop  to  it. 

I have  never  been  able  to  find  any  difference  in  the  time  of 
formation  of  callus,  between  pregnant  women  and  others.  INI. 
Boyer  avows  the  same  opinion.*  Among  the  authors  who  have 
asserted  that  fractures  could  not  consolidate  during  pregnancy, 
some  have  conjectured  that  this  depends  on  nature,  who  is 

* Lecons  de  M.  Boyer,  sur  les  Maladies  des  os,  redigees  en  un  Traits  com- 
plet  de  ces  Maladies,  par  A.  Richerand,  2 vol,  Svo. 


rudiments  of  the  foetus,  first  begin  to  be  gradually  organized  when  they 
arrive  at  their  place  of  destination,  at  a due  time,  and  under  the  necessary' 
circumstances.”  This  is  the  definition  of  a learned  writer.  The  doctrine,  how- 
ever,  may  be  more  distinctly  enunciated.  We  would  say,  that,  denying  the 
pre-existence  of  germs  in  either  parent,  the  doctrine  of  Epigenisis  supposes, 
that  the  fluid  contained  in  the  ovarian  vesicle  is  the  rude  elementary  mat- 
ter which,  after  impregnation,  becomes  organized  into  an  embryon  by  the 
energies  of  the  semen  masculinum.  The  primary  traces  of  this  doctrine  are  to 
be  met  with  in  tlie  writings  of  Aristotle.  The  prevailing  opinion  on  the 
subject  of  generation,  in  the  time  of  this  eminent  philosopher  was,  that  each 
sex  furnishes  semen,  and  that  the  embryon  results  from  an  admixture  of 
the  two  fluids  in  the  cavity  of  the  uterus.  After  confuting  the  popular 
idea  of  women  having  semen,  he  asserted  that  they  contribute  nothing 
towards  conception,  except  the  menstrual  blood:  that  the  rudiments  of  the 
embry'on  are  derived  from  the  menses,  and  are  vivified  and  put  together 
by  a plastic  power,  which  he  imputed  to  the  semen.  With  various  modifi- 
cations this  hypothesis  has  been  handed  dotvn  to  us.  It  would  be  tedious  and 
impossible  to  point  out  all  the  shapes  which  at  different  times  it  has  as- 
sumed. Of  late,  its  most  able  and  determined  supporter  is  Blumenbach,  to 
whose  system  of  Physiology,  and  Essay  on  Generation,  we  must  refer  such 
of  our  readers  as  are  desirous  of  further  information  on  this  subject. — Ed. 


ON  GENERATION. 


537 

busy  in  directing  the  humours  to  the  uterus,  forgetting,  in  sorpss 
sort,  every  other  function,  and  omitting  to  institute  the  process, 
necessary  to  the  cure.  But  as  we  shall  see,  whatever  may  be 
the  importance  of  the  uterus,  charged  during  pregnancy  with 
the  fruit  of  conception,  the  foetus  is  merely  an  organ  added  to 
the  organs  of  the  mother,  and  assimilating  to  itself  the  juices 
it  receives  from  the  uterine  vessels.  It  does  not  hinder  the 
other  parts  from  getting  their  nourishment;  they  all  go  on 
living,  and  separating  to  themselves  the  juices  their  existence 
or  their  functions  require.  Haller  ascribes  the  difficulty  with 
which  the  broken  ends  unite,  in  pregnant  women,  to  the  great 
quantity  of  earthy  matter  which  the  fetus  draws  off  from  the 
mother.  This  opinion  will  not  stand:  for,  as  I have  shown 
in  my  preliminary  discourse,  the  phosphate  of  lime  has  butlit- 
tle  to  do  in  the  work  of  re-union,  which  chiefly  goes  on  by 
changes  in  that  part  of  the  bone  which  is  really  organic.  Be- 
sides, this  hypothesis  would  imply  that  consolidation  were  as 
difficult  in  nurses,  whose  milk  carries  off  a large  quantity  of 
phosphate  of  lime.  Yet  it  has  not  been  observed  that  the  for- 
mation of  callus  is  more  difficult  during  suckling.  Lastly,  on 
this,  as  on  all  occasions,  experience  is  more  effectual  than 
reasoning;  now,  experience  shows,  that  the  time  required  for 
the  formation  of  callus,  in  pregnant  women,  is  not  sensibly 
longer  than  in  their  ordinary  state. 

Meanwhile,  the  uterus,  imbued  with  prolific  fluid,  swells,  to 
avail  myself  of  the  expression  of  a modern,  like  a lip  stung  by 
a bee:  it  becomes  a centre  of  fluxion  towards  which  the  humours 
tend  from  all  quarters.  The  diameter  of  its  vessels  increases 
with  the  thickness  of  its  parietes:  these  soften,  and  their  mus- 
cular nature  becomes  more  marked.  Till  the  end  of  the  third 
month,  the  only  appearance  of  pregnancy  is  in  the  suspension 
of  menstruation;  the  uterus,  of  which  the  cervix  has  yet  under- 
gone no  change,  has  concentrated  itself  behind  the  pubis,  but 
very  soon  it  rises  above  the  upper  outlet  of  the  pelvis,  pushing 
upwards  the  intestines  and  the  rest  of  the  abdominal  viscera. 
Towards  the  end  of  pregnancy,  it  rises  above  the  umbilicus, 
its  fundus  comes  in  contact  with  the  arch  of  the  colon,  and 
reaches  sometimes  to  the  epigastric  region.  The  compression 
it  exerts  on  the  organs  of  digestion,  explains  the  loathings,  and 

3 Y 


ON  GENERATION. 


538 

the  nausea  which  belong  to  the  state  of  pregnancy.  The  de- 
rangement of  sensibility,  by  the  affection  of  the  great  sympa- 
thetics,  accounts  equally  for  those  depraved  tastes,  those  fan- 
tastic appetites,  which  the  ignorant  think  it  so  important  to 
gratify.  When  the  term  of  pregnancy  draws  near,  respiration 
is  oppressed,  the  diaphragm  forced  upward  by  the  abdominal 
viscera,  descends  with  difficulty;  accordingly,  nature  has,  as 
much  as  possible,  delayed  this  moment  of  oppression,  by  giving 
the  lower  part  of  the  abdomen  a great  capacity,  at  the  expense 
of  the  chest,  which  in  woman,  is  much  shorter  than  in  man. 

If  the  growth  of  the  foetus,  its  size,  the  quantity  of  liquor 
amnii,  the  development  of  the  uterus,  were  always  the  same, 
we  might  settle  the  height  to  which  this  last  organ  must  rise, 
at  each  stage  of  pregnanev;  but  these  conditions  vary  so  much, 
in  every  individual,  that  the  terms  one  might  assign  would  suit 
but  a small  number:  let  it  suffice  to  have  spoken  of  the  ex- 
tremes. The  uterus  tends  to  rise  directly  upwards:  while  in- 
closed within  the  pelvis,  it  preserves  this  direction;  but,  as  soon 
as  it  has  passed  the  upper  outlet  of  the  pelvis,  it  is  no  longer 
supported,  and  inclines  forwards,  backwards,  or  to  the  sides. 
These  inclinations,  if  they  go  a certain  length,  constitute  those 
vices  of  situation  which  accoucheurs  call  obliquities  of  the 
uterus.  Their  direction  is  determined  by  the  disposition  of  the 
parts:  accordinglv,  they  almost  always  lie  forwards:  either  be- 
cause the  upper  outlet  of  the  pelvis  is  naturally  so  inclined,  and 
forms  with  the  horizon  an  angle  of  45  degrees,  or  because  the 
lumbar  column,  being  convex,  pushes  the  uterus,  which  cannot 
depress  it,  upon  the  anterior  parietes,  which  yields  the  easier, 
the  more  frequent  pregnancy  has  been. 

The  dilatation  of  the  uterus  is  not  the  effect  of  a simple  dis- 
tention of  its  parietes,  since  these,  far  from  stretching  thinner 
as  the  viscus  grows  in  size,  thicken  progressively,  on  the  con- 
trary, by  the  dilatation  of  vessels  of  all  sorts,  and  the  afflux  of 
humours.  In  this  sort  of  vegetation,  the  uterus  is  really' active, 
and  does  not  give  way  to  any'  efforts  of  the  foetus.  The  cervix 
of  this  viscus,  which  from  its  greater  consistency  had  at  first 
resisted  dilatation,  ends  by  yielding  to  the  efforts  of  the  fibres 
of  the  fundus,  on  the  edges  of  the  os  tincse;  the  edges  of  that 
opening  are  attenuated,  the  cervix  effaced,  the  orifice  enlarges, 


ON  GENERATION.  539 

and  you  may  feel  through  its  parietes,  the  fostus  plunged  in  the 
waters  which  its  membranes  contain.. 

Towards  the  term  of  gestation,  the  discharge  of  urine  is  more 
frequent,  because  the  bladder,  under  compression,  cannot  con- 
tain it  in  any  quantity.  The  lower  extremities  are  osdematous; 
the  veins  of  the  legs  varicose;  women  are  also  more  exposed 
to  haemorrhoids;  and  these  effects  depend  on  the  compression 
of  the  vessels,  which  bring  back  the  blood  and  the  lymph  of  the 
inferior  parts,  as  the  cramps,  to  which  pregnant  women  are 
subject,  depend  on  that  of  the  sacral  nerves.  The  groins  are 
alike  painful,  and  there  are  felt  in  them  twitchings  which  must 
be  ascribed  to  congestion  in  the  round  ligaments  of  the  uterus. 
Lastly,  the  skin  of  the  anterior  parietes  of  the  lower  part  of  the 
abdomen,  distended  beyond  measure,  cracks,  when  that  of  the 
neighbouring  parts  has  yielded  as  much  as  it  could. 

Before  explaining  how  the  uterus  expels  the  fetus  and  its 
covering,  at  the  term  of  gestation,  let  us  consider  a little,  this 
fruit  of  conception:  let  us  study  its  developement;  let  us  examine 
the  nature  of  the  relations  which  it  holds  with  its  mother. 

CCVIII.  History  of  the  foetus  and  its  coverings, — The  inte- 
rior of  the  uterus,  for  a short  period  after  the  instant  of  concep- 
tion, shows  nothing  that  leads  to  a knowledge  of  the  existence 
of  its  product.  But,  at  the  end  of  a few  days,  there  appears  a 
membranous  transparent  vesicle,  filled  with  a liquid  trembling 
jelly;  discovering  no  trace  of  organization  and  life.  But  the 
little  ovum  begins  to  grow,  parts  of  the  gelatinous  fluid  assume 
more  consistence,  losing  at  the  same  time  their  transparency: 
one  may  then  distinguish  the  first  rudiments  of  parts,  and  im- 
perfect appearance  of  the  head,  trunk,  and  limbs.  The  small 
ovum,  free  at  first  in  the  cavit3^  of  the  uterus,  contracts  adhe- 
sions to  this  viscus:  its  whole  exterior  surface  becomes  shaggy, 
and  this  sort  of  vegetation  is  no  where  more  marked,  than  in 
the  situation  to  be  occupied  bj’^  the  placenta.  Meantime,  to- 
wards the  seventeenth  day,  the  parts  which  showed  merely  a 
homogeneous  semi-transparent  mass,  discover  a more  determi- 
nate structure.  A red  point  appears  in  the  spot  of  the  heart,  it 
is  the  heart  itself,  distinguishable  by  the  pulsations  of  its  cavi- 
ties, and  the  motions  of  the  molecules  of  the  red  liquid  that 
fills  them.  Because  the  heart  is  the  punctum  saliens,  it  is  not 


ON  GENERATION. 


540 

therefore  to  be  concluded  that  it  is  the  jSriwww  vivens.  All  our 
parts  are  formed  together,  all  are  coev'al,  as  Charles  Bonnet 
has  said;  only  they  discover  themselves  earlier  or  later  to  the 
eye  of  the  observer,  according  as  the  nature  of  their  organiza- 
tion is  adapted  to  the  reflexion  of  light.  Were  we  to  admit  a 
successive  order  in  the  formation  of  our  organs,  the  brain  and 
the  nervous  system  might  exist  before  the  heart,  without  being 
perceptible  from  their  transparency. 

Meanwhile,  red  lines,  setting  off"  from  the  heart,  sketch  the 
course  of  the  larger  vessels,  and  seem  agitated  by  the  action  of 
these  tubes,  whose  parietes  are  still  semi-transparent.  As  the 
blood,  or  rather  its  red  part,  extends  from  the  centre  to  the 
circumference,  the  forms  become  more  determinate,  the  parts 
unfold  and  grow  rapidly:  points  quite  opake  are  seen,  and  the 
form  of  the  feetus  may  be  distinguished.  Bent  upon  itself,  the 
foetus  is  not  unlike  a French  bean,  suspended  by  the  umbilical 
cord,  which,  as  I shall  mention  by  and  by,  formed  with  the 
foetus  and  its  coverings,  proceeds  in  growth  with  them:  it 
swims  amidst  the  liquor  amnii,  changes  its  position  the  more 
easily,  as  the  space  in  which  it  is  inclosed  is  greater,  compared 
to  its  size.  As  it  grows,  it  stretches  out  a little,  without  ceas- 
ing however  to  retain  its  bent  posture  (CLXV):  the  head  com- 
poses the  greater  part  of  its  body:  the  upper  limbs,  like  little 
buds,  pullulate  first,  then  the  lower  limbs:  the  feet  and  the 
hands  appear  immediately  attached  to  the  trunk;  the  fingers 
and  toes  show  themselves  like  little  papillse.  Of  all  the  organs 
of  sense,  the  eyes  are  the  first  apparent:  they  are  discernible, 
as  two  little  black  spots,  by  the  end  of  the  first  month;  the  eye- 
lids are  produced  and  cover  them.  The  mouth,  at  first  gaping, 
closes  by  the  drawing  together  of  the  lips,  towards  the  end  of 
the  third  month.  During  the  fourth,  a reddish  coloured  fat  be- 
gins to  be  deposited  in  the  cells  of  the  mucous  tissue,  and  the 
muscles  already  exert  some  action.  The  growth  is  ever  more 
rapid,  as  the  foetus  draws  nearer  to  its  birth.  It  is  impossible  to 
assign  the  weight  and  the  length  of  the  foetus,  at  the  different 
stages  of  pregnancy,  since  the  time  of  conception  is  never  very 
certain;  and  further,  the  progress  of  growth  varying  much,  one 
foetus  at  six  months  shall  be  as  large  as  another  at  the  full  term. 


ON  GENERATION.  54  J 

Nevertheless,  at  the  time  of  birth,  the  body  is  commonly  18 
inches  long,  and  weighs  from  seven  to  eight  pounds. 

The  secretion  of  bile,  like  that  of  the  fat,  seems  to  begin, 
towards  the  middle  of  gestation,  and  tinges  the  meconium  yel- 
low, a mucus  previously  colourless,  which  fills  the  digestive 
tube:  a little  while  after  the  hairs  grow;  the  nails  are  formed 
about  the  sixth  or  seventh  month;  a very  thin  membrane,  which 
closed  the  pupil,  tears,  by  what  mechanism  is  unknown,  and 
the  pupil  is  seen.  The  kidneys  at  first  manifold,  that  is  to. say, 
formed  each  of  from  seventeen  to  eighteen  separate  glandular 
lobules,  unite,  and  form  on  each  side  a single  viscus.  Lastly,  the 
testicles,  placed  at  first  at  the  side  of  the  lumbar  column  and 
aorta,  near  the  origin  of  the  spermatic  arteries  and  veins,  then 
carried  along  the  iliac  vessels  to  the  inguinal  rings,  directed  by 
a cellular  cord,  which  Hunter  calls  the  gubernaculum  testis, 
clear  this  opening,  carrying  along  with  them  the  portion  of  the 
peritoneum,  which  is  to  form  their  tunica  vaginalis. 

This  covering  of  the  testicles,  furnished  by  the  peritoneum, 
not  only  covers  these  organs,  and  is  reflected  again  over  them, 
but  also  rises,  in  adults,  about  half  an  inch  high,  along  the 
lower  part  of  the  spermatic  cord.  If  it  do  not  reach,  it  is  said, 
to  the  inguinal  ring,  it  is  because  the  whole  portion  which, 
after  birth,  extended  from  this  opening  to  near  the  testicle,  has 
been  decomposed,  and  is  reduced  to  cellular  tissue.  Upon  re- 
flecting on  the  causes  of  the  spontaneous  decomposition  of  a 
portion  of  this  peritoneal  prolongation,  it  occurred  to  me,  that 
nothing  v/as  less  proved,  or  more  improbable;  in  fact,  in  ear- 
liest life,  the  testicles,  which  have  passed  out  from  the  abdo- 
men by  the  inguinal  rings,  are  very  little  removed  from  this 
opening.  The  portion  of  tunica  vaginalis,  which  is  carried  on 
upon  the  cord  of  the  spermatic  vessels,  rises  up  to  the  ring,  and 
even  extends  beyond;  communicating  with  the  peritoneum,  as 
is  sometimes  seen  in  congenital  bubonocele.  It  is  only  in  the 
progress  of  life,  that  the  testicles  descend  into  the  scrotum,  still 
departing  from  the  opening  which  gave  them  passage:  so  that, 
in  adults,  the  prolongation,  which  at  first  covered  the  whole 
cord,  (which,  just  after  birth,  was  not  more  than  a few  lines 
long,)  is  found  to  cover  only  its  lower  part,  when  it  is  lengthened 
some  inches,  without  any  necessity  of  decomposition;  a.pheno- 


542 


ON  GENERATION. 


menon,  which  it  is  as  difficult  to  conceive  as  to  explain.  This 
opinion  suggested,  for  the  first  time,  in  the  first  edition  of  this 
work,  is  now  almost  universally  received. 

Of  the  circulation  in  the  fcetus.  The  principal  differ- 
ence that  is  found  between  the  foetus  and  the  new-born  child, 
besides  the  inactivity  of  the  senses,  and  the  repose  of  the  mus- 
cles subject  to  volition,  lies  in  the  manner  in  which  the  circu- 
lation is  earned  on.  Too  feeble  to  assimilate  to  its  own  sub- 
stance foreign  substances,  the  foetus  receives  from  its  mother 
aliments  ready  prepared.  The  arteries  of  the  uterus  receive  a 
large  supply  of  blood;  this  is  not  all  employed  for  the  nourish- 
ment of  the  organ  itself,  but  passes  in  great  part  from  the  mo- 
ther to  the  child,  being  poured  by  the  uterine  vessels  into  the 
cells  of  a spungy  substance,  adhering  on  one  side  to  the  uterus, 
and  on  the  other  to  the  ovum  which  contains  the  foetus. 

This  cellulo-vascular  body,  known  under  the  name  of  placenta, 
is,  as  well  as  the  covering  of  the  fcetus  and  the  fcetus  itself,  a 
product  of  the  act  of  generation.  Though  it  adheres  commonly 
to  the  fundus  of  the  uterus,  it  may  adhere  to  any  other  point 
of  its  parietes;  sometimes  even  it  is  placed  on  its  orifice,  a 
circumstance  which  always  makes  delivery  difficult.  The  side 
by  which  it  is  united  to  the  internal  face  of  the  uterus  is  uneven, 
covered  with  mammillary  projections  {cotyledons)^  which  are 
sunk  in  corresponding  cells  of  the  parietes  of  the  uterus,  the 
internal  surface  of  which  loses,  as  it  develops  itself,  the  smooth- 
ness which  it  had  while  empt}',  is  furrowed  with  depressions 
destined  to  receive  the  placenta,  and  studded  with  projections 
which  penetrate  into  the  cells  of  the  latter. 

The  uterine  arteries,  and  perhaps  likewise  the  absorbents 
which  are  so  large  and  numerous  in  the  gravid  uterus,  that 
Cruickshank,  who  succeeded  in  injecting  them,  compares  them 
to  quills,  throw  out  on  the  surface  of  the  placenta  and  within 
its  spungy  tissue  the  arterial  blood  of  the  mother;  according  to 
some,  these  vessels  exhale  only  the  serous  part  of  the  blood, 
and  according  to  others  a chylous,  lymphatic,  whitish,  or  milky 
substance.^  These  fluids,  effused  within  the  cells  of  the  placenta, 

* A German  physician,  Schreger,  has  suggested  a very  ingenious  opinion 
on  the  mode  of  circulation  between  the  mother  and  child.  He  believes  that 
the  uterine  arteries  pour  out  nothing  but  serum,  into  tlie  cells  of  the  pla- 


ON  GENERATION. 


545 

are  absorbed  by  the  numerous  minute  divisions  of  the  umbilical 
vein,  which  by  their  union  form  the  trunk  of  this  vessel. 

The  umbilical  vein,  arising  from  the  interior  of  the  placenta 
by  numerous  branches,  detaches  itself  from  it  and  goes  towards 
the  umbilicus  of  the  child,  enters  his  body  at  that  aperture, 
ascends,  in  a fold  of  the  peritoneum,  behind  the  recti  muscles, 
to  the  anterior  extremity  of  the  sulcus  of  the  liver,  goes  along 
the  anterior  half  of  this  fissure,  sending  a number  of  branches 
to  the  lobes  of  that  viscus,  especially  to  the  left  lobe.  On  reach- 
ing the  right  extremity  of  the  transverse  fissure,  where  this  last 
meets  the  antero-posterior,  it  unites  in  part  with  the  sinus  of 
the  vena  portae  hepatica,  while  the  remainder  of  the  vessel, 
called  ductus  venosus,  follows  the  original  direction,- and  opens 
into  the  ascending  or  inferior  vena  cava,  very  near  to  the  spot 
where  this  vein  pours  its  contents  into  the  right  auricle  of  the 
heart. 

CCX.  The  arterial  blood  which  flows  along  the  umbilical 
vein  acquires  the  properties  of  venous  blood,  and  combines 
with  hydrogen  and  carbon,  and  parts  with  its  vivifying  qualities, 

centa.  This  serum  is  absorbed  by  tbe  lympliatics,  whose  existence  he  infers 
from  analogy,  in  this  organ  and  in  the  umbilical  cord,  in  which,  however,  no 
one  has  yet  succeeded  in  injecting  them.  These  vessels  convey  it  to  the 
thoracic  duct,  whence  it  is  poured  into  the  left  subclavian  vein,  and  at  the  last 
reaches  the  heart  which  sends  it  along  the  aorta.  It  returns  to  the  placenta 
by  the  umbilical  arteries,  after  being  converted  into  blood  by  the  action  of 
the  organs  of  the  fetus.  This  serosity,  after  undergoing  the  process  of  san- 
guification, returns  to  the  fetus  bj'  the  umbilical  vein,  and  following  the  well 
known  course  of  the  fetal  circulation,  is  subservient  to  the  nourishment  of  its 
organs.  The  branches  of  the  umbilical  arteries  and  vein,  ramified  in  the  pla- 
centa, and  communicating  together  in  this  spongy  tissue,  reject  through  the 
lateral  pores  that  which  can  no  longer  serve  to  the  maintenance  of  the  fetus. 
This  residue  of  nutrition,  deposited  in  the  cells  of  the  placenta,  is  absorbed 
by  the  lymphatics  of  the  uterus,  which  carry  it  back  into  the  mass  of  the 
fluids  of  the  mother.  Not  to  mention  the  impossibility  of  demonstrating  the 
presence  of  lymphatics,  in  the  placenta,  or  in  the  umbilical  cord,  Schreger’s 
hypothesis  is  attended  with  two  objections.  How  does  the  nutritious  fluid, 
coming  from  the  mother  and  sent  along  the  aorta  of  the  fetus  to  every  part 
of  its  body,  return  to  the  placenta,  to  be  brought  back  again  by  the  umbilical 
vein?  Absorption  scarcely  goes  on  in  the  fetus:  the  unctuous  substance  with 
which  the  body  of  the  fetus  is  covered,  prevents  that  function  from  taking 
place  on  the  surface  of  the  body.  It  goes  on,  with  very  little  more  activity, 
within  the  body;  the  excrementitious  secretions  scarcely  exist  before  birth: 
whatever  is  conveyed  to  the  fetus  is  employed  in  the  development  of  its  or- 
gans; hence  its  growth  is  so  rapid. 


544 


ON  GENERATION. 


in  flowing  along  the  vessels  of  the  mother  and  the  tortuous 
vessels  of  the  placenta.  It  parts  with  these  principles,  and  again 
becomes  vivified,  by  circulating  through  the  liver,  which  at  this 
period  of  life  fulfils  the  functions,  which  afterbirth  is  committed 
to  the  lungs.  Hence  the  liver  and  brain  form  the  greatest  part 
of  the  weight  of  a new  born  child.  The  former  alone  occupies 
the  greatest  part  of  the  abdomen.  It  acquires  this  bulk,  by  as- 
similating to  itself  the  hydrogen  and  carbon  of  the  umbilical 
blood,  its  substance  is  adipose,  oily,  and  contains  these  two 
principles  in  a considerable  proportion.  The  secretion  of  the 
bile  and  that  of  the  fat,  the  only  secretions  that  are  manifestly 
carried  on  in  the  foetus,  may  besides  supply  very  well  the  want 
of  respiration. 

The  blood  conveyed  by  the  umbilical  vein  into  the  lower  vena 
cava,  and  deposited  by  that  v-in  into  the  right  auricle,  does  not 
unite  with  that  which  is  brought  by  the  descending  cava,  from 
the  upper  parts;  for,  as  was  observed  elsewhere,  the' orifices  of 
these  two  vessels  not  being  directly  opposed  to  each  other,  the 
columns  of  blood  which  flow  in  them  do  not  meet  each  other. 
That  which  is  brought  by  the  lower  cava,  passes  through  the 
foramen  ovale,  towards  which  the  mouth  of  that  vessel  is  turn- 
ed; it  passes  into  the  left  auricle,  thence  into  the  left  ventricle, 
without  circulating  through  the  lungs,  which  containing  no  air 
and  being  dense  and  indurated,  could  not  have  received  it;  the 
contractions  of  the  left  ventricle  send  it  into  the  aorta,  the  force 
of  its  impetus  is  broken,  by  striking  against  the  great  arch  of 
this  artery.  It  enters  into  the  vessels  which  arise  from  it,  and 
these  convey  it  directly  to  the  brain  and  upper  parts.. This  blood 
is  the  most  pure,  the  most  oxygenated,  and  that  which  comes 
most  immediately  from  the  placenta;  it  has  not  yet  circulated 
in  the  body  of  the  feetus,  with  the  exception  of  a very  small 
quantity  brought  from  the  pelvis  and  lower  parts,  for  the  blood 
which  comes  from  the  abdominal  viscera,  is  purified  in  passing 
through  the  liver.  The  other  parts  of  the  body  receive,  on  the 
contrary,  blood  very  imperfectly  oxygenated,  since  the  very  in- 
considerable quantity  which  the  contractions  of  the  left  ventri- 
cle and  of  the  aorta  have  not  been  able  to  send  into  the  vessels 
arising  from  the  arch  of  this  vessel,  mixes  with  the  venous 
blood  which  is  brought  by  the  ductus  arteriosus,  immediately 


ON  GENERATION. 


545 


below  this  curvature.  Hence  the  growth  which  is  always  rela« 
tive,  not  only  in  repect  to  the  quantity,  but  likewise  to  the 
vivifying  qualities  of  arterial  blood,  is  much  more  rapid,  before 
birth,  in  the  upper  parts,  so  that  the  brain  alone  constitutes  the 
greatest  part  of  the  body,  and  the  shoulders,  the  chest  and 
the  upper  extremities  are  developed  in  a much  greater  degree 
than  the  abdomen,  and  especially  than  the  pelvis  and  lower  ex- 
tremities. 

The  blood  which  is  brought  by  the  descending  cava,  from 
the  upper  parts  of  the  body  of  the  foetus,  passes  into  the  right 
ventricle  which  forces  it  into  the  pulmonary  artery;  this  vessel 
sends  only  two  small  branches  to  the  lungs,  and  terminates  by 
a vessel  called  the  ductus  arteriosus,  into  the  aorta  immediately 
below  the  origin  of  the  left  subclavian  artery.  The  aorta,  at  its 
origin,  is  therefore  filled  with  arterial  blood,  sent  towards  the 
upper  parts  of  the  body  by  the  contraction  of  the  left  ventricle, 
while  the  remainder  of  this  artery  contains  venous  blood,  which 
is  expelled  by  the  combined  action  of  both  ventricles. 

It  is  impossible  in  this  arrangement,  not  to  recognize  an  evi- 
dent design.  In  fact,  if  the  whole  force  of  the  heart  had  been 
exerted  to  send  the  blood  towards  the  brain,  the  delicate  texture 
of  this  viscus  would  have  been  injured  by  it;  the  combined  ac- 
tion of  the  two  ventricles  was,  on  the  contrary,  required  to 
enable  the  blood  to  circulate  along  the  extensive  and  tortuous 
channels  of  the  umbilical  cord  and  placenta.  The  aorta  on  reach- 
ing the  body  of  the  fourth  or  fifth  lumbar  vertebra,  divides  into 
the  two  umbilical  arteries;  these  send  to  the  pelvis  and  to  the 
lower  parts  only  very  insignificant  branches,  which  convey  blood 
that  contains  a very  small  quantity  of  oxygen,  they  then  bend 
along  the  sides  of  the  bladder,  incline  inwards,  approach  to- 
wards the  urachus,  pass  out  of  the  abdomen  at  the  umbilicus, 
and  joining  the  umbilical  vein  which  had  entered  through  the 
same  opening  into  the  body  of  the  fcstus,  form  with  it  the  um- 
bilical cord. 

CCXI.  The  length  of  the  umbilical  cord,  measured  from  the 
umbilicus  to  the  placenta,  is  from  twenty  to  twenty-four  inches. 
It  ma*y  not  be  above  six  inches  long,  or  may  greatly  exceed  that 
length,  as  is  proved  by  a case  of  M.  Baudelocqne,  in  which 
the  umbilical  cord  was  fifty-seven  inches  in  length,  and  passed 

3 Z 


546 


ON  GENERATION. 


seven  times  round  the  child’s  neck,  which  circums  tance  hythe 
way,  shows  that  the  foetus  moves  in  its  mother’s  womb.  Of  the 
three  vessels  which  form  the  umbilical  cord,  two  which  are  the 
smallest  have  an  arterial  structure,  though  they  convey  blood 
that  is  truly  venous,  while  the  umbilical  vein  carries  arterial 
blood  to  the  foetus.  The  umbilical  arteries  on  reaching  the  pla* 
centa,  divide  and  are  lost  in  its  substance  in  a multitude  of 
vessels  whose  extremities  deposit  into  the  areolae  of  its  tissue 
the  blood  coming  from  the  foetus,  and  which  is  to  be  returned 
to  the  mother.  Does  the  course  of  injection  from  the  umbilical 
vein  into  the  arteries,  prove  that  there  exists  an  anastomosis 
between  the  extremities  of  these  vessels? 

The  foetus  is  connected  to  the  mother,  by  the  umbilical  cord 
and  placenta;  the  veins,  or  the  lymphatics  of  the  uterus,  and 
perhaps  both  these  sets  of  vessels,  take  up  in  the  spungv  tissue 
of  the  placenta,  the  blood  that  has  been  employed  in  the  nutri- 
tion of  the  fcEtus,  and  return  it  to  the  mother,  that  after  undergo- 
ing a change  by  the  action  of  her  organs,  and  especially  by  that 
of  the  atmospherical  air,  by  means  of  the  pulmonary  circula- 
tion, it  may  become  fit  for  the  nourishment  of  the  fcEtus.  Whe- 
ther we  inject  the  uterine  vessels,  or  whether  we  force  the  wax 
along  the  umbilical  vein,  it  never  fills  but  a part  of  the  placenta, 
which  has  led  to  the  division  of  this  substance  into  two  parts, 
the  one  belonging  to  the  mother,  which  has  been  called  uterine, 
the  other  called  the  foptal  portion,  which  forms  a part  of  the 
umbilical  cord. 

The  vessels  of  the  mother  do  not,  therefore,  anastomose  with 
those  of  the  foetus  within  the  placenta,  the  circulation  is  not  con- 
tinued from  the  one  to  the  other.  If  the  communications  were 
immediate,  the  beats  of  the  pulse  of  the  child,  ought  to  be 
simultaneous  with  those  of  the  mother,  whereas  they  are  much 
more  frequent,  as  may  be  observed,  at  the  time  of  birth,  before 
the  division  of  the  umbilical  cord.  If  the  veins  of  a bitch,  rea- 
dy to  whelp,  are  opened,  the  animal  dies  of  hemorrhage,  and 
her  body  remains  bloodless.  The  placenta,  however,  is  empty, 
only  in  the  part  that  adheres  to  the  uterus;  the  rest  of  the  pla- 
centa, as  well  as  the  foetus,  are  filled  with  blood,  as  usual.  It  is 
obvious,  that  if  the  vessels  of  the  uterus  had  been  directly  con- 
tinuous with  those  of  the  placenta,  delivery  would  not  have  taken 


ON  GENERATION. 


547 

place,  without  their  being  torn;  alarming  hemorrhage,  inflam- 
mation, and  even  suppuration  of  the  uterus  would  have  been 
the  consequence.  Lastly,  the  force  with  which  the  heart  and 
arteries  of  the  mother  impel  the  blood  along  her  vessels,  would 
have  been  attended  with  danger  to  the  organs  of  the  foetus, 
which  are  too  soft  to  sustain,  without  injury,  so  violent  a shock. 
Though  the  placenta  and  the  umbilical  cord  form  the  bond  of 
union  between  the  foetus  and  the  mother,  it  must  be  confessed, 
that  they  belong  chiefly  to  the  former,  and  may  be  considered 
as  a continuation  of  its  body. 

CCXII.  The  existence  of  the  foetus  is  solely  vegetative:  he 
is  continually  drawing  from  the  juices,  which  the  vessels  of  the 
mother  send  to  the  placenta,  what  is  to  serve  to  his  nourish- 
ment and  growth.  He  may  be  considered  as  a new  organ,  the 
product  of  conception,  participating  in  general  life,  but  having 
a peculiar  life,  and,  to  a certain  degree,  independent  of  that  of 
the  mother.  Bent  on  himself,  so  as  to  occupy  the  least  possible 
space,  he  cannot  be  considered  as  asleep;  for,  not  only  are  the 
organs  of  sense  and  of  motion  in  a perfectly  quiescent  state, 
but  besides,  several  of  the  functions  of  assimilation  are  inactive, 
as  digestion,  respiration,  and  most  of  the  secretions.  The  foetus 
performs,  in  the  midst  of  the  liquor  amnii,  spontaneous  motions, 
which  accoucheurs  reckon  among  the  signs  of  pregnancy.  The 
existence  of  these  phenomena  has  been  denied,  and  the  dis- 
placement of  the  foetus  has  been  ascribed  to  a mere  shaking  of 
the  body;  this  was  asserted  on  the  ground  of  the  intimate  con- 
nexion between  respiration  and  muscular  motion.  It  was  said, 
that  the  blood  of  the  foetus,  not  being  impregnated  with  oxygen 
in  its  passage  through  the  lungs,  contractility  would  not  exist. 
But  besides  that  a fact  may  be  certain,  without  being  easily 
explained,  it  may  be  answered,  that  the  mother  fulfils  this  office 
for  the  foetus,  and  sends  it  arterial  bio  od,  fitted  to  maintain  the 
contractility  of  the  muscles. 

As  we  perforra  no  motion,  but  in  virtue  of  impressions  pre- 
viously received,  and  as  the  organs  of  sense,  in  the  foetus,  are 
completely  inactive,  it  is  not  easy  to  say,  why  it  should  move 
in  the  womb.  The  touch,  however,  is  exerted,  when  any  part 
of  the  surface  of  the  body  of  the  fcEtus  comes  in  contact  with 
the  internal  part  of  the  cavity  in  which  it  is  contained.  Lastly, 


ON  GENERATION. 


548 

the  internal  impressions  experienced  by  the  great  sympathetics, 
may  act  as  an  occasional  cause  of  such  motions. 

The  foetus  is  nourished,  like  every  other  organ,  by  appro- 
priating to  itself  whatever  is  suited  to  its  nature,  in  the  blood 
brought  to  it  by  the  vessels  of  the  uterus.  The  interception  of 
this  fluid,  by  a ligature,  or  by  compression  of  the  umbilical 
cord,  would  occasion  death,  though  not,  as  has  been  imagined, 
by  a sudden  and  quick  suffocation,  but  the  action  of  the  organs 
would  become  gradually  weakened,  and  at  last  cease,  when  the 
fluids  of  the  foetus,  being  no  longer  vivified  by  the  mixture  of 
new  juices  from  the  mother,  would  be  completely  deprived  of 
their  nutritive  parts.  It  is  now  well  ascertained,  that  the  liquor 
amnii  does  not  serve  to  the  nutrition  of  the  foetus,  whose  mouth 
is  closed,  whose  head  is  bent  on  his  breast,  and  whose  intesti- 
nal canal  is  filled  with  a fluid  different  from  that  in  which  the 
whole  body  is  immersed.  Besides,  may  not  the  unctuous  sub- 
stance with  which  the  surface  of  the  skin  is  covered,  prevent 
the  absorption  which  might  otherwise  take  place  from  the  outer 
part  of  the  body? 

It  was  long  believed  that  the  foetus  was  in  an  upright  position, 
during  the  first  months  of  life,  but  that,  towards  the  end  of 
pregnancy,  it  fell  into  a different  position  and  lay  with  its  head 
downwards.  This  erroneous  opinion,  believed  from  its  antiqui- 
ty, and  because  it  was  admitted  by  several  physiologists,  is  com- 
pletely refuted  in  Professor  Baudelocque’s  work  on  Midwifery. 
The  absurdity  of  this  hypothesis  is  manifest,  if  it  be  considered 
that  the  head  of  the  embryo,  the  most  bulky  and  weighty  part 
of  the  body,  must  necessarily  occupy  the  most  depending  part. 

The  plumpness  and  strength  of  the  feetus  do  not  altogether 
depend  on  the  strength  of  the  mother.  Corpulent  and  strong 
women  often  bring  forth  pun}'  children,  while  others  who  are 
thin  and  feeble,  bring  forth  children  plump  and  healthy.  Such 
instances,  however,  are  exceptions  to  the  general  rule,  as,  caete- 
ris  paribus,  the  healthy  state  of  the  fostus  is  to  be  estimated  by 
that  of  the  mother.  The  morbid  condition  of  the  fluids  of  the 
mother  has  a considerable  influence  on  the  health  of  the  feetus, 
and  is  perhaps  the  way  in  which  hereditary  diseases  are  trans- 
mitted, which,  by  others,  are  ascribed  to  a diseased  state  of  the 


semen. 


ON  GENERATION. 


549 

The  fffitus  is  subject  to  affections  of  various  kinds,  whether 
of  spontaneous  origin  or  arising  from  a germ  received  from  the 
mother.  Foetuses  have  been  seen  with  cicaitrices,  which  clearly 
showed  that  solutions  of  continuity,  of  various  kinds,  had  taken 
place.  A child,  born  with  the  loss  of  some  limb,  has  met  with 
the  accident,  in  consequence  of  some  affection  experienced  in  the 
womb.  Professor  Chaussier  having  been  called  in  to  a case  of 
this  kind,  found  the  hand  and  a portion  of  the  fore-arm  among 
the  membranes. 

CCXIII.  Of  monsters.  As  it  is  useful  to  study  nature,  even 
in  her  irregularities,  I shall  say  a few  words  on  the  subject  of 
monsters,  adopting  the  arrangement  proposed  by  Buffon,  of 
dividing  them  into  three  classes:  the  first  including  monsters 
from  excess;  the  second,  monsters  from  defect;  the  third  in- 
cluding those  in  which  there  is  a misplacement  of  organs.  In 
the  first,  are  included  those  which  have  supernumerary  limbs 
or  fingers,  or  even  two  bodies  joined  in  various  ways.  In  the 
second,  children  born  with  a harelip,  or  who  are  deficient  in  some 
one  part.  In  the  last  place,  those  monsters  belong  to  the  third 
class,  in  which  there  is  a general  transposition  of  organs;  when, 
for  example,  the  heart,  the  spleen  and  the  sigmoid  flexure  of 
the  colon  are  on  the  right  side,  and  the  liver  and  csecum  on  the 
left;  those  born  with  hernise  of  different  kinds,  likewise  belong 
to  this  class.  One  may  reckon  among  those  monstrous  confor- 
mations, spots  in  the  skin,  the  colour  of  which  always  resembles 
that  of  some  of  our  fluids,  but  whose  various  forms  are  purely 
accidental,  though,  from  prejudice,  one  is  apt  to  imagine  some 
likeness  to  objects  longed  for  by  pregnant  women  accustomed 
to  those  fantastic  appetites  and  longings,  so  frequent  during 
pregnancy. 

Various  attempts  have  been  made  to  account  for  these  unna- 
tural formations:  some,  as  Mallebranche,  attributed  them  to  the 
influence  of  the  mother’s  imagination  on  the  foetus  in  the  womb; 
others,  as  Maupertuis,  thought  that  her  passions  communicated 
to  her  humours  irregular  motions,  which,  acting  with  violence 
on  the  delicate  body  of  the  embryo,  disturbed  its  structure. 
Disease,  while  the  child  is  in  utero,  is  a much  more  probable 
cause  of  such  affections. 


ON  GENERATION. 


550 

If  two  foetuses,  contained  in  one  ovum,  lie  back  to  back,  and 
if  the  surfaces  at  which  they  are  in  contact  become  affected 
with  inflammation,  it  is  easy  to  conceive  that  adhesion  may  take 
place  between  them.  By  placing,  in  a confined  vessel,  the  fecun- 
dated ova  of  a tench  or  any  other  fish,  the  numerous  young 
ones,  which  are  formed,  not  having  space  sufiicient  for  their 
growth,  adhere  to  each  other,  and  fishes  truly  monstrous  in  their 
formation  are  produced. 

When,  from  disease,  or  from  an  original  malformation,  the 
body  of  the  foetus  is  deficient  in  some  of  its  parts,  the  others 
are  better  nourished  and  grow  to  a large  size.  Hence,  in  ace- 
phalous monsters,  as  there  is  no  brain,  the  blood  which  should 
be  sent  to  that  viscus,  going  to  the  face,  it  acquires  a remarka- 
ble enlargement. 

One  of  the  most  curious  of  all  the  cases  of  monstrosities  de- 
pending on  an  original  defect  in  the  organization  of  the  germs, 
is  that  which  was  sent,  a few  years  ago,  by  the  Minister  of  the 
Interior  to  the  School  of  Medicine  at  Paris.  I shall  give  an 
abstract  of  it,  from  a more  detailed  account,  drawn  up  with 
much  accuracy  and  sagacity  by  M.  Dupuytren. 

A young  man,  thirteen  years  of  age,  had  complained  from 
his  earliest  infancy,  of  pain  in  the  left  side  and  lower  part  of 
the  abdomen.  This  side  had  been  prominent  and  contained  a 
tumour,  from  the  earliest  period  of  life.  At  the  age  of  thirteen 
he  was  seized  with  fever,  the  tumour  increased  in  bulk,  and 
became  very  painful.  Some  days  after  he  voided  by  stool,  pu- 
rulent and  fetid  matters;  at  the  end  of  three  months,  he  became 
wasted  by  marasmus,  he  passed,  by  stool,  a ball  of  hairs,  and, 
in  the  course  of  a few  weeks,  died  of  consumption. 

On  opening  his  body,  there  was  found,  in  a cavity  in  contact 
with  the  transverse  arch  of  the  colon,  and  communicating  with 
it,  some  balls  of  hair  and  an  organized  mass.  The  cyst,  situa- 
ted in  the  transverse  mesocolon,  near  the  colon,  and  externally 
to  the  digestive  canal,  communicated  with  the  intestine.  But 
this  communication  was  recent  and  accidental,  and  one  could 
plainly  see  the  remains  of  the  septum  between  these  cavities. 
The  organized  mass  presented,  in  its  forms,  a great  number  of 
features  of  resemblance  with  the  human  foetus,  and,  on  dissec- 
tion, no  doubt  could  be  entertained  of  its  nature.  There  was 


ON  GENERATION. 


551 

discovered  it  in  the  trace  of  some  of  the  organs  of  sense,  a brain, 
a spinal  marrow,  very  large  nerves,  muscles  converted  into  a 
sort  of  fibrous  matter,  a skeleton  consisting  of  a vertebral  co- 
lumn, a head  and  pelvis,  and  limbs  in  an  imperfect  state;  lastly, 
a very  short  umbilical  cord  attached  to  the  transverse  mesoco- 
lon, at  the  outer  part  of  the  intestine,  an  artery  and  vein,  rami- 
fying at  each  of  their  extremities,  where  they  were  in  contact 
with  the  foetus  and  with  the  individual  which  contained  it. 
much  is  sufficient  to  establish  the  distinct  existence,  as  an  indi- 
vidual, of  this  organized  mass,  though,  in  other  respects,  desti- 
tute of  organs  of  digestion,  of  respiration,  of  the  secretion  of 
urine,  and  of  generation.  The  absence,  however,of  a great  num- 
ber of  the  organs  necessary  to  the  maintenance  of  life,  should 
make  it  be  considered  as  one  of  those  monstrous  foetuses,  not 
destined  to  live  beyond  the  moment  of  birth.  This  foetus  was 
evidently  contemporary  with  the  boy  to  whose  body  it  was 
attached.  Similar  to  the  product  of  extra-uterine  conceptions',  it 
received  its  nourishment  from  that  which  may  be  considered 
as  its  brother,  and  whose  germ  had  originally  enclosed  its  own. 
During  the  thirteen  years  of  the  life  of  Bissieu  (this  was  the 
name  of  the  subject  of  this  singular  case),  the  organized  mass 
obtained  from  the  mesocolon,  by  means  of  vessels  of  its  own, 
the  blood  necessary  for  its  existence;  this  blood,  propelled  by 
the  organs  of  circulation  into  the  body  of  the  fcetus,  returned 
afterwards  to  the  mesocolon  of  the  boy  who  had  so  long  been 
to  him  as  a mother.  At  last,  the  period  fixed  by  nature  for 
expulsion,  being  arrived,  and  this  expulsion  being  impractica- 
ble, the  cyst  became  inflamed;  the  inflammation  extended  to  the 
intestine,  the  part  which  separated  these  two  cavities  was  de- 
stroyed, and  the  cyst  opened  into  the  colon;  pus  and  hairs  were 
voided  by  stool,  and  the  patient  died  of  marasmus.  The  draw- 
ings of  different  parts  of  the  body  of  this  fetus,  taken  by  M. 
Cuvier  and  M.  Jadelot,  render  this  interesting  case  most  com- 
plete. They  will  be  published  in  the  first  volume  of  the  trans- 
actions of  the  Academical  Society,  near  the  Faculty  of  Medi- 
cine at  Paris.* 

* Mr.  Young,  of  London,  has  communicated  a case  of  the  same  kind,  in  a 
valuable  paper  inserted  in  the  first  volume  of  the  .Medico-Chirurgical  Trans- 


ON  GENERATION. 


552 

We  ought  not  to  be  too  ready  to  place  implicit  confidence  m 
the  extraordinary  stories  contained  in  the  older  writers,  and 
even  in  some  of  the  moderns.  In  reading  the  periodical  publi- 
cations  of  the  seventeenth,  and  even  of  the  eighteenth  century, 
one  is  apt  to  wonder  at  the  marvellous  things  which  they  con- 
tain. Among  other  strange  cases,  is  that  of  a girl  that  was  born 
with  a pig’s  head;  another  of  a woman  who  was  delivered  of 
an  animal,  in  every  respect  like  a pike.  There  was  a time,  says 
a philosopher,  when  philosophy  consisted  merely  in  seeing  pro- 
digies in  nature. 

CCXIV.  Of  the  coverings  of  the  foetus.  The  name  of  after- 
birth is  given  to  the  envelopes  of  the  foetus,  because  they  are  not 
expelled  from  the  uterus,  till  after  the  birth  of  the  child.  The 
ovoid  sac,  which  contains  the  foetus,  is  formed  by  two  mem- 
branes in  contact  with  each  other.  The  name  of  chorion  is  given 
to  that  which,  by  its  external  and  shaggy  surface,  adheres  to  the 
inside  of  the  uterus:  the  other,  a concentric  membrane  to  the 
former,  but  of  less  thickness,  and  to  be  considered  as  the  secre- 
tory organ  of  the  fluid  which  fills  the  ovum,  is  called  the  am- 
nion. The  third  envelope,  admitted  by  Hunter,  and  called  by 
that  physiologist,  the  membrana  decidua,  is  nothing  more  than 
the  lanuginous  tissue  presented  by  the  external  part  of  the  cho- 
rion, after  tearing  the  multitude  of  cellular  and  vascular  fila- 
ments by  means  of  which  the  ovum  adheres  to  the  uterus. 
The  placenta  is  itself  merely  a thicker  portion  of  nearly  the 
same  tissue,  in  which  the  umbilical  vessels  are  ramified.  The 
uterus  is  also  thicker  at  the  part  which  corresponds  to  the  pla- 
centa, because  it  is  there  that  the  communication  of  the  foetus 
with  the  mother  is  established. 

The  liquor  amnii  is  a serous  fluid,  of  a sweetish  odour,  of 
insipid  taste,  rendered  slightly  turbid  by  a milky  substance 
which  it  holds  suspended,  and  somewhat  heavier  than  distilled 
water,  1,004.  It  is  almost  completely  aqueous;  albumine,  soda, 
muriate  of  soda  and  phosphate  of  lime,  discovered  in  it  by 

actions.  In  Mr.  Young’s  case,  the  ftxtus  was  contained  in  a cyst  that  seemed 
to  answer  the  purpose  of  membranes  and  placenta;  it  was  without  a brain, 
but  had  imperfectly  formed  digestive  organs  and  extei^ial  organs  of  genera- 
tion.— See  vol.  1st  of  the  Medico-Chirnrgical  Transactions.  T. 


ON  GENERATION. 


553 


MM.  Buniva  and  Vauquelin,  forming  only  0,012  of  the  whole 
mass.  It  turns  of  a green  colour,  cincture  of  violets,  and  red- 
dens that  of  turnsol;  a very  remarkable  circumstance,  as  is 
observed  by  the  last  mentioned  philosophers,  and  indicating  the 
co-existence  of  an  alkali  and  of  an  acid  in  separate  state.  The 
latter  is  in  so  small  a quantity,  so  volatile,  and  so  soluble  in  the 
liquor  amnii  of  woman,  that  it  has  never  yet  been  obtained  by 
itself;  there  is  found,  however,  in  the  liquor  amnii  of  the  cow, 
a peculiar  acid,  called  by  MM.  Buniva  and  Vauquelin,  the 
amniotic  acid.  The  liquor  amnii  is  in  greater  quantity,  in  pro- 
portion to  the  size  of  the  foetus,  according  as  the  latter  is  nearer 
the  period  of  its  formation.  It  is  the  product  of  arterial  exhala- 
tion. Its  materials  are  supplied  by  the  blood  conveyed  by  the 
vessels  of  the  uterus.  This  is  proved,  not  merely  by  analogy, 
but  likewise  by  observing  the  connection  between  the  qualities 
of  the  liquor  amnii  and  the  regimen  of  the  mother.  In  a woman 
who  had  used  mercurial  friction,  in  the  course  of  her  preg- 
nancy, the  liquor  amnii  was  observed  to  whiten  copper. 

The  fundus  of  the  bladder  in  quadrupeds,  is  continuous  with 
a canal,  of  which  the  rudiments  are  observed  in  man,  and  which 
is  called  the  urachus.  This  canal  joins  the  umbilical  vessels, 
passes  out  with  them  at  the  umbilicus,  and  terminates  in  a 
membranous  sac,  between  the  chorion  and  the  amnion;  it  is 
called  the  allantois;  it  is  always  found  in  the  foetus  of  the  lower 
animals,  but  it  is  very  indistinct,  and  often  does  not  exist  in 
man.  Some  anatomists  say  they  have  seen  the  urachus  arising 
from  the  human  bladder,  and  which  is  commonly  ligamentous, 
terminate  in  a small  vesicle  which  some  of  them  compare  to  a 
melon  seed;  while  others  say  its  bulk  does  not  exceed  a millet 
or  hemp  seed.  So  small  a vesicle  can  certainly  answer  no  pur- 
pose; the  urachus  always  forming  a solid  cord,  seldom  pervious, 
and  even  of  very  small  bore,  in  the  part  nearest  the  fundus  of 
the  bladder.  The  existence  of  these  parts  furnishes  an  addi- 
tional proof  of  what  was  stated  in  speaking  of  the  uses  of  the 
valve  of  the  caecum,  viz.  that  there  are  in  the  animal  body,  or- 
gans which  answer  no  purpose,  and  which  merely  indicate  the 
•plan  which  nature  has  followed  in  the  reproduction  of  beings, 
and  the  gradations  which  she  has  uniformly  observed  in  the 
divisions  of  the  species. 

4 A 


554 


ON  GENERATION. 


CCXV.  Of  the  natural  term  of  gestation.  The  foetus  may 
exist  without  the  maternal  influence,  when  arrived  at  the  period 
of  seven  or  eight  months  from  the  instant  of  conception.  All 
accoucheurs  agree  that  it  may  be  delivered  alive  at  this  period, 
and  that  it  stays  two  months  longer  in  the  uterus,  only  that  it 
may  gain  more  strength,  and  be  better  fitted  to  resist  the  new 
impressions  which  it  is  to  experience  on  coming  into  the  world. 
A child,  however,  has  been  known  to  live,  though  born  at  the 
sixth  month  of  pregnancy,  in  premature  labour;  but,  in  general 
the  child  is  the  more  likely  to  live  when  born  at  the  usual  pe- 
riod; that  is,  towards  the  end  of  the  ninth  solar  month,  or  of 
the  tenth  lunar.  It  is  observed,  that  children  born  at  seven 
months,  however  robust  they  may  prove  afterwards,  are  very 
feeble  when  born,  have  their  eyes  closed,  and  are  in  a state  of 
extreme  debility  and  suffering,  during  the  two  months  which 
they  ought  to  have  spent  in  their  mother’s  womb;  this  proves 
how  necessary  it  is  that  gestation  should  be  carried  on  to  the 
end  of  the  ninth  solar  month. 

If  the  foetus  may  live,  though  separated  from  its  mother, 
before  the  natural  period,  may  it  not  likewise  remain  longer 
within  the  womb,  grow  with  less  rapidity,  and  be  expelled 
some  days,  weeks,  and  even  months  later?  How  difficult  there- 
fore will  it  not  be  to  assign  a precise  term,  beyond  which  we 
shall  not  be  able  to  admit  the  possibility  of  a late  birth! 

There  are  said  to  be  authentic  cases  of  children  born  more 
than  ten  months  after  conception;  yet  the  laws,  which  cannot  be 
founded  on  rare  exceptions,  do  not  allow  of  so  long  a period  in 
deciding  of  the  legitimacy  of  children  born  after  the  dissolution 
of  matrimony. 

CCXVI.  Of  parturition.  When  the  fcetus  has  remained  suf- 
ficiently long  within  its  mother’s  womb,  to  acquire  the  degree 
of  strength  required  for  its  insulated  existence,  it  becomes 
separated  from  her, carrying  along  with  it  the  parts  which  enclos- 
ed it,  and  by  which  it  was  connected  to  the  uterus.  Its  expulsion 
from  the  uterus  is  called  delivery.  The  most  ridiculous  opinions 
have  been  entertained,  with  regard  to  the  causes  which  deter- 
mine the  coming  on  of  labour;  according  to  some,  Fabricius 
of  Aquapendente  for  instance,  it  is  the  want  of  fresh  air,  which 
makes  the  foetus  rupture  its  membranes;  according  to  others, 


ON  GENERATION. 


555 

the  foetus  is  determined  to  the  same  process,  by  the  necessity 
of  voiding'the  meconium,  an  excrementitious  fluid,  which  fills 
the  intestinal  canal.  It  has  been  said  that  the  fetus  was  urged 
to  it  by  the  want  of  food,  or  that  labour  depends  on  the  re- 
action of  the  fibres  of  the  uterus,  which  distended  beyond 
measure,  towards  the  end  of  pregnancy,  close  on  themselves, 
and  overcome  the  resistance  of  the  cervix  uteri,  which  is  thinned 
and  gradually  dilated.  But,  if  this  last  hypothesis  be  correct, 
and  is  the  only  one  that  is  at  present  in  any  esteem,  how  comes 
it,  that  in  a woman,  whose  uterus  is  of  a determinate  size,  la- 
bour does  not  come  on  when  there  are  twins,  at  the  end  of  four 
months  and  a half,  by  which  period  the  same  degree  of  disten- 
tion would  be  produced,  as  by  one  child  at  the  full  time. 

It  is  very  true,  that  for  a fortnight,  and  even  sometimes  for 
a month  before  labour,  the  uterus  seems  to  be  preparing  for 
the  expulsion  of  the  fetus.  This  at  least,  may  be  inferred  from 
the  prominence  of  the  cervix  of  the  uterus,  which  may  then 
sometimes  be  felt;  and  which  is  evidently  produced  by  the 
membranes  containing  the  waters,  which  insinuate  themselves 
within  the  orifice  of  the  uterus,  when  this  organ  contracts,  and 
which  collapse  and  recede,  when  the  uterus  is  relaxed. 

The  product  of  conception  after  a certain  time,  reaches  a 
period  at  which  it  may  exist,  separated  from  the  mother.  When 
this  period  is  arrived,  the  ovum  in  which  it  is  contained,  de- 
taches itself  from  the  uterus,  by  a mechanism,  in  every  respect 
similar  to  that,  by  which  the  stalk  of  a ripe  fruit  drops  from  the 
bough  on  which  it  hung.  Then,  in  all  probability  the  fetus  re- 
fuses to  admit  the  blood  sent  to  it  by  the  umbilical  vein.  The 
placenta  becomes  affected  with  congestion;  this  stagnation  of 
the  fluids  extends  gradually  to  the  uterus,  and  to  the  neighbour- 
ing parts.  Stimulated  by  their  presence,  these  organs  are  called 
into  action,  the  woman  feels  wandering,  irregular  pains,  similar 
to  col'C  pains,  which  become  more  acute,  are  attended  with  a 
feeling  of  constriction,  and  act  from  above  downwards,  that  is, 
from  the  fundus  to  the  cervix  of  the  uterus. — This  contractile 
cavity,  assisted  by  the  diaphragm  and  abdominal  muscles,  then 
acts  with  redoubled  effort  to  expel  its  contents.  The  pains  be- 
come more  acute  and  frequent;  the  face  red,  the  pulse  full  and 
frequent,  the  whole  body  seems  to  partake  in  the  affection  of 


ON  GENERATION. 


556 

the  uterus,  and  is  agitated  with  convulsive  motions.  The  mem- 
branes, filled  with  the  waters,  force  themselves  like  a wedge 
through  the  mouth  of  the  uterus,  whose  edges  are  much  weak- 
ened; the  throes  of  labour  increase  in  strength  and  number, 
the  membranes  rupture,  the  liquor  amnii  escapes,  the  head  of 
the  child  follows,  and  it  soon  clears  the  mouth  of  the  uterus 
with  most  excruciating  pains. 

These  pains  are  particularly  severe,  when  the  sacrum  not 
being  sufficiently  concave,  the  nerves  of  the  sacral  plexus  are 
violently  compressed  by  the  head  of  the  foetus;  this  part  of  the 
body  almost  always  presents  first;  it  passes  through  the  upper 
outlet  of  the  pelvis,  in  an  oblique  direction,  the  occip«t  being 
turned  forward,  and  corresponding  to  one  of  the  acetabula, 
whi!e  the  face  is  directed  backward  towards  one  of  the  sacro- 
iliac junctions.  It  passes  thus  along  the  greatest  diameter  of  the 
pelvis,  but  in  descending  lower  down  in  the  pelvis,  it  describes 
a portion  of  a circle,  and  passes  through  the  lower  outlet  of  the 
pelvis,  at  its  greatest  diameter,  which  is  from  the  fore  to  the 
back  part.  The  head  descends  through  the  vagina,  appears  out- 
wardly, soon  disengages  itself,  and  is  followed  by  the  shoulders 
and  the  rest  of  the  body.  Thus  it  is  that  nature,  after  having 
produced  fecundation  by  an  act  attended  with  pleasure,  expels 
the  product  of  conception  in  the  midst  of  pain. 

CCXVII.  The  passages  along  which  the  foetus  is  carried  out 
of  the  body,  would  be  too  confined,  in  their  ordinary  state,  to 
allow  expulsion  to  take  place  without  laceration,  if,  as  I am  go- 
ing to  explain,  nature  had  not  disposed  every  thing  to  facilitate 
labour.  In  fact,  nature  has  not  only  formed  the  foetal  skull  of 
several  flexible  pieces,  separated  by  membranous  unossified 
spaces,  so  as  to  allow  the  bones  to  move  over  one  another,  and 
the  whole  head  to  be  reduced  in  size,  in  passing  through  the 
female  pelvis,  but  she  has  besides  united  the  bones  of  the  pelvis, 
in  such  a manner,  that  their  articulations  become  evidently  re- 
laxed towards  the  end  of  pregnancy.  During  the  progress  of 
pregnancy,  the  fluids  of  the  mother  flow  in  every  direction  to- 
wards the  pelvis  and  the  parts  which  it  contains;  the  ligamcnto- 
cartilaginous  aijticulations  of  the  pubis,  of  the  sacrum  and 
coccyx,  soaked  in  fluids,  unite  with  less  firmness  the  bones  be- 
tween which  they  are  placed.  Hence,  being  softened  and  swollen, 


ON  GENERATION. 


557 

they  do  not  force  them  asunder  like  a wedge,  by  increasing  the 
diameters,  but  facilitate  the  separation  of  the  bones,  by  the 
passage  of  the  head  through  the  pelvis.  It  is  on  the  relaxation 
of  the  articulations  of  the  pelvis,  that  the  indication  for  the 
operation  of  dividing  the  symphysis  pubis,  rests;  an  operation 
performed  successfully  by  Sigault  and  by  Professor  Alphonse 
Leroy.  Analog}^  led  very  naturally  to  this  operation,  as  is  judi- 
ciously observed  by  M.  Thouret,  in  the  same  manner  that  the 
invention  and  application  of  the  forceps  were  founded  on  a 
consideration  of  the  means  employed  by  nature,  to  lessen  the 
bulk  of  the  child’s  head,  during  the  progress  of  labour. 

The  foresight  of  nature  is  not  limited  to  the  facilitating  the 
motion  on  one  another  of  the  osseous  parts  of  the  skull  of  the 
fcjtus,  and  of  the  pelvis  of  the  mother;  her  care  extends  to  the 
soft  parts  of  the  latter;  these  are  soaked  in  mucus,  so  as  to  re- 
lax their  tissue  several  days  before  parturition,  and  are  so  dis- 
posed, as  was  already  observed  (CCI),  that  the)’  may,  without 
rupture  or  violence,  and  by  the  mere  unfolding  of  the  folds  of 
the  skin,  yield  to  a considerable  degree.  As  the  placenta  and 
membranes  are  not  expelled,  immediately  after  the  foetus,  it  is 
customary  to  separate  them  by  dividing  the  umbilical  cord  near 
the  navel.  It  is  unnecessary  to  tie  this  cot;d,  at  the  part  near 
the  mother,  every  communication  being  intercepted  between 
the  placenta  and  the  uterus,  so  that  no  blood  could  flow  but 
that  of  the  placenta.  Not  so,  however,  with  the  part  nearest 
the  foetus;  though  the  changes  which  take  place  in  the  circula- 
tion, at  the  moment  when  the  chest  is  dilated,  and  allows  the 
air  to  distend  the  pulmonary  tissue,  divert  the  blood  from  the 
umbilical  vessel;  these  changes,  however,  in  the  circulation  of 
the  fluids  might  come  on  slowly  from  the  weakness  of  the  new 
born  child:  hence  it  is  always  prudent  to  prevent  by  a ligature 
a loss  of  blood  that  tvould  increase  the  debility. 

The  human  ov’um  is  very  seldom  detached  entire,  and  never 
so  without  considerable  danger;  that  is,  the  foetus  is  not  expelled 
with  its  membranes  and  in  the  liquor  amnii,  for  these  are  not  in 
general  expelled  till  a quarter  of  an  hour,  half  an  hour,  or  even 
a full  hour  after  the  delivery  of  the  foetus.  When  the  uterus  is 
completely  emptied,  its  cavity  becomes  obliterated  by  the  ap- 
proximation of  its  sides;  this  organ  contracted  on  itself,  sinks 


ON  GENERATION. 


558 

behind  the  pubis,  its  cervix  closes  and  this  even  impedes  the 
delivery  of  the  after-birth,  when  the  latter  is  protracted  too 
long.  The  parietes  of  the  uterus,  imbued  with  fluids,  are  thicker 
than  in  their  natural  condition:  but  they  decrease  in  size,  in 
consequence  of  the  lochial  discharge,  and  return  to  their  wonted 
thickness. 

Vv’hen  the  labour  is  over,  the  uterus  falls  as  it  were  asleep, 
and  enjoys  repose  after  painful  exertion.  The  humours  cease  to 
be  determined  to  that  organ,  towards  which  they  are  no  lo.iger 
directed  by  any  irritation,  and  they  flow  towards  the  mammary 
glands,  to  supply  the  secretion  of  the  fluid  which  is  to  nourish 
the  new  born  child. 

CCXVIIl.  Of  twins.  Though  in  the  human  subject  the 
offspring  is  generally  single,  it  is  not  uncommon  for  a woman 
to  bring  forth  two  children  at  once;  it  has  been  ev^  n calculated, 
that  the  proportion  of  twin  cases  to  single  births,  was  as  one  to 
eighty.  Indeed,  there  are  cases  of  women  who  have  brought 
three  children  at  a birth.  Haller  calculates  that  the  number  of 
these  last,  to  those  of  single  births,  is  as  one  to  seven  thousand. 
The  cases  of  four  children  at  a birth,  are  still  less  frequent,  and 
if  three  children  born  at  once,  seldom  live  long,  the  others  which 
when  born,  are  of  the  size  of  children  at  five  months,  cannot 
live.  Only  one  or  two  instances  are  known  of  five  children  hav- 
ing been  born  at  a birth;  Haller,  therefore  is  guilty  of  exaggera- 
tion in  saying  that  these  cases  are  to  the  ordinary  cases,  in  the 
proportion  of  one  to  a million.  I take  no  notice  of  the  instances 
in  which  a greater  number  are  said  to  have  been  delivered  at 
once,  because  those  cases  are  not  well  authenticated.  In  the 
case  of  twins,  each  child  has  its  own  umbilical  cord,  terminat- 
ing sometimes  in  a separate,  and  sometimes  in  a single  placenta. 
Both  foetuses  are  enveloped  in  one  chorion,  but  each  has  a dis- 
tinct amnion,  and  floats  in  a separate  liquor  amnii.  It  would  be 
curious  to  know  whether  in  women  who  have  had  twins,  as 
well  as  in  animals,  one  should  find  two  cicatriculae,  both  in  the 
same  ovarium,  or  one  in  each.  Twins  are,  generally,  very  like 
one  other  in  features,  and  dispositions. 

The  multiplicity  of  foetuses  in  the  same  pregnancy,  is  occa- 
sioned by  the  presence  of  several  vesiculee,  ready  to  be  detached 
from  the  ovaria,  and  consequently  ripe  for  fecundation.  This 


ON  GENERATION. 


559 


multiplicity  of  offspring  contributes  very  little  to  iricrease  popu- 
lation, for  they  are,  in  general,  less  robust  and  strong,  and  not 
so  capable.of  reproduction;  they,  besides,  exhaust  the  strength 
of  the  mother,  and  their  birth  is  often  fatal  to  her.  The  num- 
ber of  children  which  a woman  might  bring  into  the  world, 
from  the  period  of  puberty  to  the  cessation  of  the  menstrual 
discharge,  would  be  much  greater  than  it  generally  is,  if  no 
time  were  lost.  Some  women  have  been  known  to  have  twenty- 
four,  thirty,  thirty-nine, and  even  fifty-three  children.  A woman 
died  in  North  America,  after  having  had  five  hundred  children 
and  grand-children,  of  whom  two  hundred  and  five  survived 
her. 

It  is  now  well  known,  that  the  number  of  male  children  who 
are  born,  exceeds  in  general,  that  of  the  females.  The  differ- 
ence, in  some  countries,  is  estimated  at  one  in  twenty-one,  at  a 
fourteenth,  a twelfth,  and  sometimes,  though  rarely,  at  a third. 
In  all  countries  of  the  world,  polygamy  is  therefore  in  direct 
opposition  to  the  intentions  of  nature,  and  to  the  multiplica- 
tion of  the  species;  this  is  proved  in  a most  undeniable  manner, 
by  the  loss  of  population  in  those  countries  in  which  this  prac- 
tice exists.  The  boys,  more  numerous  than  the  girls  during 
the  early  part  of  life,  exposed  afterwards  to  the  dangers  of  war, 
of  navigation,  and  occupied  in  laborious  occupations,  lead  a 
more  laborious  and  anxious  life,  and  die  in  greater  numbers, 
so  that  the  equilibrium  is  soon  restored,  and  the  least  numerous 
portion  of  the  human  species  at  the  cradle,  forms  about  two 
thirds  of  it  in  old  age,  since  we  always  see  more  women  than 
men  reach  a very  advanced  age. 

CCXIX.  Of  superf (Stations.  The  cases  of  foetuses  born  with 
unequal  degrees  of  development,  are  not  to  be  considered  as 
superfcctations,  but  as  twin  cases.  Thus,  if  in  a case  of  twins,  one 
foetus  is  of  its  full  size,  while  the  other  is  an  embryo  whose 
size  does  not  exceed  that  of  a foetus  in  the  first  month;  it  does 
not  fbllow  that  their  conception  took  place  at  different  and  dis- 
tant periods,  but  merely  that  for  some  reason  or  other,  one  of 
the  germs  has  been  incapable  of  growth  and  development. 

To  settle  the  question  of  superfostations,  one  should  know 
whether  a woman,  with  a single  uterus,  is  capable  of  conceiv- 
ing, two  months  after  effective  copulation.  Haller  is  of  opinion, 


560 


ON  GENERATION. 


that  the  cervix  of  the  uterus  is  always  open  to  the  semen;  but 
how  is  the  latter  to  reach  the  ovaria,  through  the  adhesions  of 
the  chorion  to  the  uterus?  It  appears  easier,  where  the  two 
conceptions  are  separated  by  a short  interval;  thus,  the  Ameri- 
can woman  mentioned  by  Buffon,  who,  in  the  course  of  one 
morning,  had  connexion  with  her  husband  and  with  a negro 
slave,  bore  two  children  of  different  colours.  Hence,  likewise, 
it  sometimes  happens,  that  one  of  two  twins  is,  by  its  features, 
a living  testimony  of  adulter)'. 

Two  children,  born  with  an  interval  of  some  months  between 
their  births,  cannot  be  considered  as  twins,  though  they  may 
have  existed  some  time  together  within  the  mother’s  womb. 
The  possibility  of  such  superfostations  is  well  proved;  they  are 
ascribed  to  septa,  dividing  the  uterus,  sometimes  into  two  cavi- 
ties, merely  because  such  an  arrangement  would  explain,  to  a 
certain  degree,  how  two  conceptions  might  take  place,  at  some 
interval  from  one  another;  for  it  has  never  been  ascertained,  by 
actual  dissection,  that  any  woman,  in  whom  such  superfoetations 
took  place,  had  a double  uterus. 

* It  seems  to  me,  that  a belief  in  superfoetations  can  hardly  be  entertained 
by  any  one  who  is  conversant  with  the  human  economy,  and  particularly 
with  the  changes  which  the  uterine  system  undergoes  in  consequence  of 
pregnancy.  W'e  know  that  soon  after  conception,  the  os  tincae,  as  well  as 
the  internal  apertures  of  the  fallopian  tubes,  are  closed  by  a deposition  of  a 
thick  tenacious  mucus.  But  to  accomplish  still  more  perfectly  an  end  so  im- 
portant to  the  scheme  of  generation  as  the  occlusion  of  the  uterus,  nature 
resorts  to  another  provision. 

By  the  sprouting  forth  of  minute  blood-vessels,*  or  by  the  effusion  of  a 
species  of  lymph,f  or  out  of  coagulated  blood,J  a membrane  of  some  firmness 
of  texture  is  quickly  fprmed.  This  membrane,  which  is  called  decidua,  or 
caduca,  from  its  being  shed  at  the  period  of  delivery,  lines  completely  the 
uterus,  and  thus  co-operates  with  the  dense  mucus  already  alluded  to,  in 
obliterating  the  three  openings  into  its  cavity. 

Such  too,  is  the  enlargement  of  the  gravid  uterus,  and  the  change  thereby 
produced  in  the  relative  position  of  its  appendages,  that  a new  series  of  im- 
pediments arises  to  the  frustration  of  a second  conception. 

In  this  state  of  tiie  organ,  it  is  accurately  ascertained,  that  the  tubes  lie 
parallel  to  its  sides,  and  subsequently  in  the  progress  of  gestation,  become 
bound  in  the  same  situation,  instead  of  running  in  a transverse  direction 
tow’ards  the  ovaries,  wuth  their  extremities  loose  and  fluctuating. 

tV'ere 


* K alter. 


f Dr.  Hunter. 


I Mr.  Hunter. 


ON  GENERATION. 


561 

CCXX.  Of  suckling.  Nothing  is  more  generally  known  in 
physiology,  than  the  strict  sympathy  which  subsists  between 
the  uterus  and  mammae;  a connexion,  in  consequence  of  which, 
these  two  organs  are  called  into  action  at  the  same  period  of 


Were  an  embryon,  therefore,  to  be  generated  by  an}'-  anomalous  combina- 
tion  of  circumstances,  the  tubes  could  not  possibly  embrace  the  fecundated, 
vesicle,  and  the  embryon,  of  course,  must  remain  in  the  ovary,  or  fall  into 
the  abdomen,  constituting  an  extra  uterine  conception. 

Let  us,  however,  withdraw  all  the  obstacles  which  have  been  enumerated 
to  the  passage  of  the  embryon,  and  admit  the  j)racticability  of  its  reaching 
the  uterine  cavity.  What  in  this  event  would  happen?  Disorganization  fatal 
to  each  foetus  must  ensue. 

It  is  to  be  recollected,  that  the  uterus  had  prepared,  in  the  first  instance, 
whatever  was  required  for  the  reception,  the  nourishment,  and  evolution  of 
the  foetus.  It  had  originally  supplied  it  with  a decidua,  as  a medium  of 
attachment,  and  afterwards  with  a placenta  for  still  more  important  pur= 
poses.  For  the  second  foetus,  the  same  offices  are  to  be  rendered.  These 
it  could  not  execute,  without  suspending  the  action  existing  at  the  time, 
and  taking  on  such  as  are  necessary  to  the  fabrication  of  an  additional  deci- 
dua and  placenta. 

That  actions  so  incompatible  cannot  co-exist,  strikes  me  as  sufficiently 
obvious.  Were  the  uterus,  therefore,  to  attempt  this  new  process,  the  res  ult 
would  be,  the  separation  of  the  primary  decidua  and  placenta,  occasioning 
an  abortion,  accompanied  with  hemorrhage,  which  would  sweep  out  the 
whole  of  its  contents. 

It  is  probably,  on  this  account,  that  menstruation  uniformly  ceases  with 
the  accession  of  pregnancy.  I am  aware,  that  this  is  a point  not  altogether 
conceded.  The  weight  of  authority  is,  however,  decidedly  against  menstru- 
ation continuing  during  gestation.  By  all  the  very  recent  writers  it  is  de- 
nied. Those  who  hold,  or  I might  rather  say,  did  hold  the  contrary  opinion, 
have  mistaken  a hemorrhagy  from  the  vagina,  which  sometimes  recurs  with 
considerable  periodical  regularity,  for  the  catamenial  flux.  Several  cases  of 
this  kind  have  come  under  my  own  observation,  where  I had  an  opportunity 
of  Inspecting  the  discharge  accurately.  In  every  instance,  I found  it  pure 
coagulable  blood,  having  neither  the  colour,  nor  odour,  nor  any  other  of  the 
peculiar  properties  of  the  genuine  menstrual  fluid. 

By  again  adverting  to  the  condition  of  the  pregnant  uterus,  we  shall  see 
that  a suppression  of  the  catamenia  is  exactly  what  ought  to  be  expected. 
The  deciduous  membrane  is  framed  while  the  process  of  conception  is  pro- 
ceeding in  the  ovary.  The  vessels  which  had  secreted  the  catamenia  are 
now  engaged  in  a new  operation.  They  form  the  membrane  and  then  sup- 
port it  While  thus  employed,  their  secretory  function  is  suspended.  They 
cannot  at  the  same  period,  perform  actions  so  incongruous  and  inconsistent. 
The  one  must  yield  to  the  other.  This  is  a very  strikingly  illustrated  by  the 
fact  which  has  not  been  sufficiently  attended  to,  that  in  a large  proportion  of 
the  cases  of  obstinate  amenorrhea,  the  membrana  decidua  exists,  and  that 

4 B 


ON  GENERATION. 


562  ' 

life,  are  evolved,  and  cease  to  perform  their  functions,  at  the 
same  time,  when  woman  becomes  incapable  of  co-operaiing  in 
the  reproduction  of  the  species.  I shall  not  endeavour  to  ac- 
count for  this  sympathy,  by  ascribing  it  to  the  influence  of  the 
nervous  system,  or  to  the  anastomosis  of  the  epigastric  with 
the  internal  mammary  arteries;  an  anastomosis  which  is  not 
uniform,  for,  instead  of  inosculating  with  each  other,  these  ves- 
sels frequently  terminate  in  the  recti  muscles  of  the  abdomen. 
But  even  though  this  anastomosis  should  exist,  as  distinctly  as 
it  is  often  met  with  in  some  subjects,  it  would  not  account  for 
this  sympathy,  since  the  uterus  and  the  mammae  often  receive 
no  branches  from  the  epigastric  and  mammary  arteries,  and 
when  they  do  they  are  exceedingly  small. 

The  new-born  child,  on  being  brought  in  contact  with  the 
breasts,  applies  his  mouth  to  the  nipple,  and  withdrawing  his 
tongue,  while  with  his  lips  he  compresses  the  edges  of  the  nip- 
ple, he  draws  in  the  fluid  whose  flow  is  facilitated  by  the  erec- 
tion of  the  lactiferous  tubes.  These  ducts,  from  twelve  to  fif- 
teen in  number,  not  only  become  enlarged,  when  the  nipple, 
which  almost  entirely  consists  of  them,  is  elongated  by  being 

the  first  symptom  of  the  return  of  the  discharge  is  the  coining  away  of  the 
membrane.  Of  the  identity  of  the  two  membranes,  there  can  be  no  doubt. 
It  has  been  determined  by  very  competent  judges.* 

By  one  less  averse  than  myself  to  speculative  reasonings  in  matters  of 
science,  a variety  of  considerations  of  this  nature,  might  be  pressed  against 
the  hypothesis  which  I am  combating.  It  could,  I think,  in  particular,  be 
urged  with  great  plausibility,  that  changed  as  is  the  whole  uterine  system 
by  gestation,  not  only  in  the  mechanical  distribution,  but  also  in  the  struc- 
ture and  functions  of  its  parts,  it  cannot  possibly  assume  that  peculiar  con- 
dition which  seems  indispensable  to  conception.  Of  all  the  operations  of  the 
animal  economy,  that  of  conception  undoubtedly  requires  the  most  harmo- 
niously concerted  action  in  the  several  organs  by  which  it  is  commenced, 
carried  on  and  consummated.  Derangements  in  any  one  portion  of  this  com- 
plex apparatus  are  confessedly  productive  of  sterility.  So  essential,  indeed, 
to  the  generative  process  in  the  human  species,  is  a perfect  integrity  in  the 
functions  of  the  uterine  system,  that  by  the  suppression  or  even  vitiation  of 
the  catamenia,  the  aptitude  to  conception  is  lost  or  diminished.  But  enough 
of  these  speculations;  I am  content  to  rest  the  defence  of  the  questi.  n on  the 
facts  which  I have  stated.  If  they  be  correct,  it  results  that  superfoetation 
cannot  take  place  in  the  human  species. — Ed. 


*Baillie,  Burns,  &c.  &c. 


ON  GENERATION. 


565 

drawn  out  by  the  child,  but,  besides,  being  excited  by  his 
touch,  they  become  affected  with  a certain  degree  of  erection, 
and  emit  their  fluid.  This  excretion,  like  that  of  other  glands, 
is  excited  by  the  touch  and  the  motion  of  the  hands  of  the 
child  on  his  nurse’s  breasts.  The  use  of  these  gentle  compres- 
sions, is  not  so  much  to  express  the  milk  mechanically,  as  to 
excite  of  the  organ  to  excretion. 

The  irritation,  produced  by  the  child  on  the  nipple,  is  the 
most  powerful  exciting  cause  of  the  determination  of  milk  into 
the  breasts;  this  irritation,  or  any  other  of  the  same  kind,  is 
sufficient  to  excite  the  secretion  of  milk,  even  under  circum- 
stances not  provided  for  by  nature.  It  is  thus  that  virgins 
have  been  enabled  to  suckle  another  mother’s  child;  that 
young  girls,  under  the  age  of  puberty,  have  had  so  complete  a 
secretion  of  milk,  so  as  to  furnish  a pretty  considerable  quantity 
of  this  fluid.  There  have  been  known  men,  in  whom  a long 
continued  titillation  of  the  breasts  had  determined  so  consi- 
derable an  afflux  of  the  humours,  that  there  oozed  from  them, 
a whitish,  milky,  and  saccharine  fluid,  not  unlike  the  milk  of  a 
woman.  The  sucking  of  the  new  born  child  is  necessary  to 
keep  up  the  secretion  of  milk  in  the  mammae.  It  ceases  to  be 
formed  in  them,  when  the  child  is  committed  to  the  care  of  a 
different  nurse;  the  mammae,  at  first  turgid,  soon  collapse, 
especially  if  care  have  been  taken  to  determine  the  fluids 
downwards,  by  exhibiting  gentle  laxatives. 

The  erection  of  the  breasts,  by  titillation  on  the  nipple,  the 
spasmodic,  and  almost  convulsive  action  which  follows  this 
kind  of  excitement,  may  be  carried  so  far  as  to  produce  an 
emission  of  the  fluid  to  some  distance.  While  its  excretion 
lasts,  women  experience  in  their  breasts  an  agreeable  sensa- 
tion; these  parts  are  tense  and  swollen;  they  feel,  as  they  ex- 
press it,  the  milk  rising;  several  feel  a sensation  of  extension 
reaching  to  the  axilla,  to  the  arms  and  chest.  The  whole  mass 
of  cellular  substance  surrounding  the  breasts  and  extending  to 
the  neighbouring  parts,  partakes  in  their  activity. 

The  breasts,  themselves,  consist,  in  great  measure,  of  cellu- 
lar substance;  an  adipose  and  lymphatic  layer,  of  a certain 
thickness,  covers  the  gland,  which  is  divided  into  several 


564 


ON  GENERATION. 


lobes,  and  incloses  it  within  its  substance.  They  receive  a num> 
ber  of  nerves,  but  very  few  blood-vessels  for  their  bulk. 

Their  structure  appears  almost  wholly  lymphatic;  the  vessels 
of  this  kind,  after  being  distributed  to  the  neighbouring  glands, 
and  especially  to  those  of  the  axilla,  penetrate  into  the  breasts, 
in  which  their  proportion,  compared  to  that  of  the  sanguineous 
vessels,  is  as  eight  to  one.  These  lymphatic  vessels,  which  en- 
ter in  considerable  numbers  into  the  composition  of  the  breasts, 
increase  greatly  in  size,  in  nurses;  and  when  injected  in  this 
condition,  it  has  been  ascertained,  that  several  of  them  joined 
to  form  larger  trunks,  which  going  towards  the  nipple,  contri- 
buted in  forming  what  are  called  the  lactiferous  tubes.  If  the 
lymphatic  vessels  be  immediately  continuous  with  the  excretory 
ducts  of  the  breasts,  there  is  reason  to  believe,  that  it  is  these 
vessels  which  convey  the  materials  of  the  fluid  which  they 
separate,  especially  if  it  be  considered  how  small  the  number 
of  minute  arteries  which  are  distributed  into  their  tissue,  and 
what  a disproportion  there  is  between  the  caliber  of  these 
small  vessels  and  the  quantity  of  blood  which  the  breasts  sub- 
ply. The  opinion  that  the  lymphatic  vessels  bring  to  the 
breasts  the  materials  of  the  secretion  of  milk,  is  not  in  oppo- 
sition to  the  laws  of  the  circulation  in  the  lymphatics;  all  who 
are  acquainted  with  these  laws,  know  that  the  course  of  the 
lymph,  though  in  general,  from  the  circumference  to  the  centre, 
is  naturally  liable  to  a number  of  aberrations  or  deviations, 
facilitated  by  the  numberless  anastomoses  of  these  vessels. 
(XLV). 

CCXXI.  The  granulated  structure  is  not  as  apparent  in  the 
breasts,  as  in  the  other  glandular  organs,  hence  they  bear  a 
greater  resemblance  to  the  lymphatic,  than  to  the  conglome- 
rate glands.  The  milk  which  they  secrete,  has  always  been 
considered  as  very  like  the  chyle,  which  it  resembles,  in  its 
white  colour,  its  smell,  and  its  saccharine  taste.  Like  the  chyle, 
it  is  the  least  animalized  fluid,  the  sweetest,  that  on  which  the 
action  of  the  organs  produces  the  least  effect,  and  that  which 
preserves  most  the  characteristic  qualities  of  the  food  taken  by 
the  nurse. 

It  is  well  known,  that  instead  of  giving  medicines  to  infants 
at  the  breast,  we,  most  frequently,  administer  the  medicine  to 


ON  GENERATION. 


565 

the  nurse;  thus,  the  milk  acquires  purgative  qualities,  and  acts 
on  the  bowels  of  the  child,  when  the  nurse  has  been  purged. 
The  chyle  is  white  and  opake,  only  in  those  animals  which 
suckle  their  young;  in  the  others, dt  is  as  transparent  as  lymph. 
(Cuvier.) 

In  the  last  place,  if  the  arteries  carried  to  the  breasts  the 
materials  of  their  secretion,  these  vessels  ought  to  increase  in 
size,  when  these  organs  become  twice,  or  even  three  or  four 
times  larger  than  natural;  in  the  same  manner  that,  in  open  can- 
cer, and  in  other  similar  affections,  in  which  the  determination 
of  blood  being  increased,  the  caliber  of  the  vessels  is  propor- 
tioned to  them.  Nothing,  however,  of  the  same  kind  occurs, 
whatever  size  the  breasts  may  acquire  from  the  presence  of 
milk;  their  arteries  preserve  their  almost  capillary  minuteness, 
as  I had  an  opportunity  of  ascertaining,  by  injecting  the  mam- 
mae of  a woman  twenty-nine  years  of  age,  who  died  in  the 
second  month  of  suckling,  and  whose  breasts  were  remarka- 
ble by  their  size,  and  by  the  quantity  of  milk  they  were  able  to 
secrete. 

Notwithstanding  all  these  reasons,  which  have  long  made 
me  adopt  the  opinion  of  the  celebrated  Haller,  who  considers 
the  milk  as  immediately  extracted  from  the  chyle,  I own  that 
it  must  be  considered  as  hypothetical,  and  resting  solely  on 
probability.  The  impossibility  of  demonstrating,  anatomically, 
the  branches  going  from  the  mesentery  to  the  breasts,  without 
communicating  with  the  thoracic  duct,  gives  still  greater  pro- 
bability to  the  generally  received  opinion,  which  makes  the 
milk,  like  all  the  other  secreted  fluids,  with  the  exception  of 
the  bile,  to  be  supplied  by  arterial  blood. 

The  milk  does  not  resemble  chyle,  in  every  respect,  though 
it  may  be  considered  as  extracted  from  the  food*,  changed  in 
its  way  to  the  mammae,  by  the  glands  through  which  it  has 
passed,  and  especially  by  the  action  of  the  organs  themselves. 
This  action  is  so  evident,  that,  as  Bordeu  observes:  “ There 
are  women  who  seem  to  have  no  milk  in  their  breasts,  which 
are  flaccid  and  empty;  but  as  soon  as  the  child  excites  them, 

* “Lac  utilis  alimenti  est  superfluum.”  Gal.  De  Usu  part.  Lib.  VII.  Cap. 
XXII. 


566 


ON  GENERATION, 


they  become  distended,  and  the  milk  comes  spontaneously.” 
It  is  well  known,  and  the  same  author  has  pointed  it  out,  that 
women,  cows,  and  the  females  of  other  animals,  allow  them- 
selves more  willingly  to  be  sucked  by  a suckling  that  knows 
how  to  excite  their  sensibility,  and  to  apply  due  irritation  to 
the  nipple;  and  that,  on  the  contrary,  they  retain  their  milk, 
when  the  suckling  does  not  excite  the  sensation  in  which  they 
feel  pleasure.  It  is  thought,  in  some  countries,  that  serpents 
know  how  to  tickle  the  teats  of  cows,  and  that  these  animals 
enjoy  this  excitement  and  allow  themselves  to  be  sucked  by 
these  reptiles. 

CCXXII.  Of  the  phnsical  properties  of  milk^  and  of  the 
chemical  nature  of  this  fiu  'id.  The  quantity  of  milk  is  in  general, 
proportioned  to  that  of  the  aliments,  to  the  degree  of  their 
nutritious  qualities,  to  their  moist  and  farinaceous  nature. 
Though  it  equals  in  weight  about  one  third  of  the  quantity  of 
food  taken  by  the  nurse,  it  may  exceed  that  proportion,  or  may 
not  come  up  to  it.  Its  specific  gravity,  even  when  the  milk  is 
lightest,  is  greater  than  that  of  distilled  water,  and  is  always 
proportioned  to  its  consistency.  The  latter  quality  is  in  an  in- 
ferior degree  in  woman,  but  is  greater  in  the  cow,  the  goat, 
the  ass,  and  the  ewe.  Its  fluidity  is  intermediate  between  that 
of  aqueous  and  oily  liquids;  its  colour,  its  smell  and  flavour 
have  something  very  peculiar,  and  by  which  it  is  easily  recog- 
nized; in  the  last  place,  it  is  not  exactly  alike,  at  different 
periods  of  the  same  milking.  This  is  proved  by  the  work  of 
MM.  Deyeux  and  Parmentier  on  milk,  a work  abounding  in 
valuable  observations,  and  which  may  be  considered  as  the 
complete  history  of  this  animal  fluid.  They  observed  that  the 
milk  first  drawn  from  the  cow  is  serous,  that  its  consistency 
gradually  increases,  and  that  the  richest  milk  is  that  which  is 
obtained  towards  the  end  of  milking,  as  if  the  fluid  contained 
in  the  udder  were  affected  by  the  laws  of  gravitation.* 

The  milk,  when  exposed  to  the  open  air  in  a vessel,  becomes 
decomposed  like  the  blood,  and  separates  into  three  parts;  the 
serum,  the  curd  or  cheesy  part,  and  the  fatty  part  or  cream. 

* The  author  seems  toforp^et  that  he  is  speaking  of  the  cow,  and  that  her 
udder  hangs  in  a situation  unfavourable  to  this  hypothesis.  T. 


ON  GENERATION. 


567 

The  latter,  which  is  lighter  than  the  others,  is  always  on  the 
surface,  and  its  quantity  depends,  not  only  on  the  richness  of 
the  milk,. but  also  on  the  extent  of  the  surface  by  which  it  is 
in  contact  with  the  air;  and  this  proves,  as  was  first  observed 
by  Fourcroy,  that  the  oxygen  of  the  atmosphere  has  some  in- 
fluence on  its  separation.  The  caseous  part,  which  coagulates 
spontaneously,  appears  albuminous  and  abounds  in  oxygen. 
MM.  Parmentier  and  Deyeux  consider  it  as  the  colouring 
matter  of  milk,  and  as  giving  to  it  its  most  characteristic  pro- 
perties. Lastly,  the  serum  or  whey,  which  alone  constitutes  the 
greatest  part  of  this  fluid,  contains  besides  a peculiar  acid 
{the  lactic  acid')  which  is  formed  when  this  substance  is  allow- 
ed to  remain  for  some  time;  a saccharine  matter,  which  may 
be  obtained  by  evaporation,  and  which,  when  crystallized  in 
rhomboidal  parallepipeds,  constitutes  the  sugar  of  milk,  whose 
purity  depends  on  the  degree  of  care  with  which  the  process 
has  been  carried  on.  This  sugar  of  milk  contains,  as  Scheele 
first  ascertained,  while  endeavouring  by  means  of  the  nitric 
acid,  to  convert  it  into  the  oxalic,  a peculiar  acid  in  the  form  of 
a powder,  difficult  of  solution,  and  to  which  he  gave  the  name 
of  saclactic  acid.  Milk  may  be  considered  as  one  of  the  most 
compound  of  the  animal  fluids,  whose  qualities  are  very  va- 
riablc'^nd  whose  parts  have  but  an  imperfect  affinity  to  each 
other.  So  that  it  is  liable  to  spontaneous  decomposition,  and 
this  takes  place  very  easily.  This  kind  of  emulsion  contains 
but  a small  quantity  of  azote,  so  that  it  retains  its  vegetable 
character.  Hydrogen,  carbon,  and  oxygen  predominate  in 
milk;  in  the  last  place,  it  contains  several  salts,  amongst  others 
muriate  of  soda,  muriate  of  potash,  and  phosphate  of  lime. 

The  presence  of  the  two  last  of  these  substances,  leads  to 
the  following  considerations.  Muriate  of  potash,  as  is  observ- 
ed by  Rouelle,  does  not  exist  in  the  blood;  the  probability  is, 
therefore,  that  it  is  not  the  blood  which  supplies  the  mammae 
with  the  materials  whence  the  milk  is  secreted,  muriate  of 
potash  being  found,  in  greater  quantity  in  milk,  than  muriate 
of  soda.  These  salts  of  potash,  on  the  contrary,  are  found  in 
considerable  proportions,  in  the  chyle,  formed  from  vegetable 
substances;  which  would  lead  one  to  think,  that  milk  is  fur- 
nished by  the  absorbent  system.  The  phosphate  of  lime  which 


ON  GENERATION. 


568 

is  found,  in  smaller  quantity,  in  the  urine  of  nurses,  and  which 
is  wholly  determined  towards  the  mammae,  was  absolutely 
necessary  in  a fluid  which  supplies  nourishment  to  the  new 
being,  while  the  bones  become  indurated,  and  all  the  parts 
acquire  solidity. 

If  we  now  wish  to  inquire  into  the  causes  which  render 
suction  necessary,  and  which  subject  the  new-born  child  to 
this  peculiar  mode  of  nutrition,  these  causes  will  be  found  in 
the  general  weakness  of  its  organs.  The  organs  of  digestion 
would  have  been  incapable  of  extracting,  from  the  aliments, 
their  nutritive  parts,  these  substances  not  having  undergone 
the  due  degree  of  trituration,  from  the  want  of  teeth,  and  from 
the  imperfect  state  of  the  other  organs  of  mastication.  It  was 
of  consequence,  therefore,  that  the  mother  should  perform 
this  preliminary  function,  and  that  she  should  transmit  the 
aliment  ready  digested.^'  It  is  not,  however,  to  be  imagined, 
that  the  milk  passes,  without  undergoing  any  change,  into  the 
vessels  of  the  child;  the  child  digests  the  milk,  and  obtains 
from  it,  in  a short  space  of  time,  and  without  effort,  a conside- 
rable quantity  of  nutritious  particles,  necessary  to  the  rapidity 
of  its  growth. 

The  connexion  between  the  mother  and  child  is  far  from 
being  broken,  at  the  period  of  birth;  the  relations  between 
them,  though  not  so  close,  are  not  less  indispensable.  Before 
birth,  the  vital  power  was  so  limited  in  the  child,  that  it  was 
necessary  it  should  receive  a fluid  already  animalized,  and  in 
a state  to  yield  to  the  function  of  assimilation  and  nutrition. 
When  the  child  has  breathed,  when  its  strength  is  increased, 
it  may  be  entrusted  with  a greater  share  of  the  process;  it  is 
then  sufficient  that  the  aliment  should  have  undergone  the  first 
degree  of  elaboration,  within  the  digestive  canal.  But  it  is  not 
merely  to  assist  in  preparing  its  food,  that  the  neu  -bv  n child 
requires  the  aid  of  the  mother;  its  lungs,  which  are  delicate  and 
imperfectly  evolved,  do  not  supply  a due  quantity  of  oxygen 
to  the  blood  which  circulates  through  them;  the  animal  heat 
would  be  under  what  is  required  by  the  wants  of  life,  if  the 

* Lac  est  ciltus  exacti  confcctus.  Galenus  de  usu  partium. 

Lib.  VII.  cap.  XXII. 


ON  GENERATION. 


569 


ftiother  did  not  make  up  for  this  deficiency,  by  transmitting 
some  of  her  own  warmth.  She  folds  her  infant  gently  to  her 
bosom',  warms  it  with  her  breath,  and  by  this  kind  of  maternal 
incubation  continues  to  cherish  it  with  that  calorific  influence 
to  which  it  was  fully  exposed,  while  forming  a part  of  herself. 
Besides,  she  feels  for  it,  keeps  it  from  danger,  foresees  its 
wants,  and  understands  its  language;  and  this  very  interesting 
intercourse  takes  place,  after  the  bonds  of  their  physical  com- 
munication are  loosened;  but  it  does  not  tear  them  asunder. 
The  infant  is,  therefore,  detached  from  the  mother  only  by 
degrees,  since  it  is  only  in  proportion  as  it  grows  older,  that 
it  acquires  the  means  of  living  independent. 

The  secretion  of  milk,  in  the  breasts,  may  be  prevented  by 
irritation  in  the  uterus,  if  the  labour  have  been  difficult,  if  the 
woman  have  suffered  a certain  degree  of  injury,  the  irritation 
in  the  parts  so  affected,  prevents  the  determination  of  the  fluids 
towards  the  mammae.  Hence  these  organs  collapse,  during 
puerperal  fever;  not  that  the  milk  flows  back  into  the  hu- 
mours, and  becomes  the  cause  of  the  complaint,  but  that  the 
inflammation  of  the  uterus  prevents  the  fluids  from  flowing  in 
their  natural  direction. 

During  the  first  few  days  after  delivery,  the  parietes  of  the 
uterus  discharge  a fluid,  at  first  bloody,  then  of  a reddish  co- 
lour, and,  in  the  last  place,  mucous  and  whitish,  termed  the 
lochia. 

CCXXIII.  All  the  parts  of  the  lungs  are  not  distended 
with  air,  in  the  first  inspirations  of  the  child,  after  birth.  Some 
of  the  lobes  which  are  harder  and  more  compact,  take  some 
time  to  admit  this  fluid,  and  even  sometimes  altogether  re- 
ject it.  A child  died  twenty-one  days  after  birth;  the  body  was 
opened  by  Professor  Boyer.  On  examining  the  lungs,  he  found 
that  the  posterior  part  of  these  organs  was  as  hard  and  com- 
pact as  in  the  fcEtal  state.  The  anterior  part  alone  was  distend- 
ed, contained  air,  .could  be  felt  to  crepitate,  and  floated  in 
water.  The  heart  was  examined,  to  ascertain  whether  its  struc- 
ture was  connected  with  this  condition  of  the  lungs,  which 
depended  on  the  want  of  power  in  the  respiratory  functions. 
The  foramen  ovale  was  found  pervious,  so  that  the  blood 
could  pass  from  the  right  into  the  left  cavities  of  the  heart, 

4C 


ON  GENERATION. 


S70 

without  flowing  through  the  lungs.  The  child  had  been  exceed- 
ingly languid,  during  the  whole  of  its  short  life;  its  skin  was, 
at  times  pale,  at  others  livid.  It  was  very  difficult  to  keep  it 
warm. 

The  child  of  Madame  died  nine  days  afterbirth, 

with  the  same  appearances.  I opened  the  chest,  and  found  the 
upper  part  of  both  lungs  indurated  and  compact;  the  foramen 
ovale  was  quite  pervious.  This  aperture  is  often  closed  very 
imperfectly,  so  that  there  remains,  at  the  upper  part  of  it,  an 
opening,  varying  in  size,  which  would  enable  a small  quantity 
of  venous  blood  to  pass  from  the  right  into  the  left  auricle,  if 
these  cavities  did  not  contract  at  the  same  moment,  and  if  the 
fluid  which  they  contain,  did  not  present  equal  resistance  on 
both  sides.  There  are  cases  of  persons,  in  whom  the  foramen 
ovale  remained  pervious,  and  who,  nevertheless,  lived  to  a 
pretty  advanced  age.  Their  skin  was  purple  and  livid,  all  their 
moral  and  physical  faculties  feeble  and  torpid.  It  would  be 
interesting  to  ascertain,  by  dissection,  whether  in  good  divers, 
who  can  remain  a long  while  under  water,  without  breathing, 
the  foramen  ovale  is  not  imperfectly  inclosed. 


S7l 


CHAPTER  XL 

CONTAINING  THE  HISTORY  OP  THE  AGES,  THE  TEMPERAMENTS 
AND  THE  VARIETIES  OF  THE  HUMAN  SPECIES;  OF  DEATH,  AND 
PUTREFACTION. 

CCXXrV.  Of  infancy.  The  epidermis  of  the  new-born  babe 
thickens,  the  redness  of  the  skin  grows  paler,  the  wrinkles  are 
effaced,  the  soft  down,  which  covered  the  face,  falls  and  dis- 
appears; the  buttocks  swell  out  and  soon  conceal  the  opening 
of  the  rectum.  During  the  first  month  of  life,  it  seems  to  need 
nothing  but  nourishment  and  sleep.  In  the  meanwhile,  the 
understanding  is  beginning  to  form,  it  looks  fixedly  at  objects, 
and  seeks  to  take  cognizance  of  all  the  bodies  that  surround  it. 
Confined,  at  first,  to  the  uneasy  sensations,  which  it  expresses 
by  almost  continual  cries,  its  existence  becomes  less  painful, 
as  it  grows  accustomed  to  the  impressions  of  outward  things 
upon  its  delicate  organs.  Towards  the  middle  of  the  second 
month,  it  becomes  capable  of  agreeable  sensations.  If  it  feels 
them  before  that  time,  at  least  it  is  only  then  that  it  begins  to 
express  them  by  laughing.* 

CCXXV.  Detention.  Towards  the  end  of  the  seventh  month, f 
the  middle  incisor  teeth  of  the  upper  jaw,  cut  through  the 

* At  Hercules  risus  prsecox  ille  et  celerrimus,  ante  quadragesimum  diem 
nulli  datur. — Plln.  Hist.  Nat.  Prsef.  ad  lib.  VIII. 

f It  would  be  very  difficult  to  say,  why  a tertian  fever  often  terminates  of 
itself,  when  it  has  reached  its  seventh  paroxysm,  whilst  a continued  fever  is 
judged  of  by  critical  evacuations,  in  seven,  fourteen,  or  twenty-one  days;  why 
delivery  happens  at  the  end  of  nine  months;  why  the  first  teething  begins  at 
seven  months  old,  the  second  at  seven  years;  why  puberty  shows  itself  to. 
wards  the  fourteenth  year,  and  menstruation  is  repeated  at  determinate  periods. 
Nature  appears  to  subject  herself,  in  all  her  acts,  to  certain  periods,  which  ob- 
servation may  ascertain,  without  any  possibility  of  arriving  at  a knowledge  of 
the  causes  of  these  phenomena  so  easy  to  establish.  Because  their  manifesta- 
tion is  correlative  to  certain  numerical  terms,  we  are  not  to  put  faith,  like 
Pythagoras,  in  the  power  of  numbers,  and  believe  that  the  number  3 and  the 
numbers  7 and  9 enslave  all  nature  to  their  supreme  influence.  We  find  traces 
of  this  ancient  error  in  all  sciences,  in  all  religions,  even  in  those  of  enlightened 
nations. 


ON  AGES. 


572 

substance  of  the  gums:  a little  while  after,  the  corresponding 
incisors  of  the  lower  jaw  show  themselves:  next,  the  lateral 
incisors  of  the  upper  jaw,  those  of  the  lower,  then  the  cuspidati, 
in  the  same  order.  At  the  age  of  between  eighteen  months  and 
two  years,  the  small  molar  teeth  appear,  but  in  reversed  order; 
those  of  the  lower  preceding  those  of  the  upper  jaw.  When 
these  molar  teeth  have  come  through,  the  first  dentition  is 
complete;  the  life  of  the  child  is  more  secure:  it  was  before 
very  uncertain,  since  the  calculations  of  the  probable  duration 
of  human  life  show,  that  a third  of  the  children  born  at  any 
given  time,  die  before  the  age  of  twenty-three  months.  Con- 
vulsions and  diarrhoeas  are  the  most  fatal  accidents  attending 
difficult  dentition.  To  these  twenty  teeth  are  added  two  new 
grinders  in  each  jaw,  when  the  child  has  reached  the  end  of  his 
fourth  year.  These  last  will  afterwards  become  the  first  large 
grinders.  They  differ  from  those  that  precede  them  in  this,  that 
they  are  to  remain  all  life  long,  whilst  the  primitive  or  milk 
teeth  are  lost  at  seven  years  old,  in  the  same  order  in  which 
they  appeared,  and  are  replaced  by  new  teeth,  better  formed, 
and  larger,  excepting  the  small  grinders,  and  with  longer  and 
more  perfect  roots.  Towards  the  ninth  year,  two  new  large 
grinders  appear  beyond  the  others.  The  child  has  then  twenty- 
eight  teeth,  and  dentition  is  complete,  though  between  eighteen 
and  thirty,  ahd  sometimes  much  later,  the  dentes  sapientiae,  two 
to  each  jaw,  show  themselves  at  the  extremities  of  the  alveolar 
processes. 

The  order  observed  in  the  successive  cutting  of  the  teeth,  is 
not  so  invariable,  but  it  is  frequently  inverted.  A child  ten  years 
old,  now  under  my  care,  cut  the  four  first  small  grinders  before 
the  canine  teeth.  Dentition  is,  in  this  respect,  like  all  other  acts 
of  the  living  economy:  instability  is  its  principal  character.  An 
attentive  examination  soon  shows  how  irregularly  those  phe- 
nomena proceed,  whether  physiological  or  pathological,  which 
appear  the  most  to  be  subjected  to  calculable  and  determinate 
periods.* 

This  double  range  of  successive  teeth  existed  in  the  jaws  of 
the  foetus.  Each  alveolar  process,  at  that  age  of  life,  contains 

* See  Erreiirs  populaires,  sec:  edit:  Cbap  4.  des  Annies  cUniateriques,  ei  des 
Joxws  critiques  dans  les  maladies. 


ON  AGES. 


573 

two  membranous  follicles,  lying  one  over  the  other.  That 
which  is  to  form  the  primitive  tooth  swells  the  first,  a calcare- 
ous matter  covers  its  surface  and  forms  the  body  of  the  tooth, 
which  invades  also  the  follicle  bv  which  the  osseous  part  is 
secreted,  so  that  the  growth  of  the  little  bone  being  completed, 
the  membranous  vesicle,  in  the  parietes  of  which  the  dental 
vessels  and  nerves  branch  out,  is  found  in  the  centre  of  its 
body,  and  adheres  to  the  parietes  of  its  internal  cavity.  It  is 
difficult  to  say,  why  the  growth  of  the  dental  germs  is  succes- 
sive; why,  in  the  seventh  year,  the  primitive  teeth  are  detach- 
ed, and  are  replaced  by  others  which  have  remained  so  long 
buried  within  the  alveolar  processes.  Dentition  is  like  all  the 
other  phenomena  of  the  living  economy;  it  is  subject  to  end- 
less varieties  in  its  period  and  duration,  &c.  Thus,  teeth  of  a 
third  set  have  been  known  to  be  cut  in  very  old  people.  There 
are  instances,  but  they  are  very  scarce,  of  children  that  have 
come  into  the  world  with  two  incisors  in  the  upper  jaw;  there 
are  often  supernumerary  teeth.  See. 

CCXXVI.  Ossification,  The  process  which  goes  on  in  the 
osseous  system,  is  not  confined  to  the  cutting  and  growth  of 
the  little  bones  which  are  attached  to  the  two  jaws.  All  other 
parts  of  the  skeleton  harden;  osseous  nuclei  are  formed  in  the 
centre  of  the  cartilages,  which  hold  the  place  of  the  short  bones 
of  the  carpus  and  tarsus;  the  thickness  of  the  cartilaginous  sub- 
stances, which  separate  the  epiphyses  of  the  bodies  of  the  long 
bones,  is  diminished;  the  large  bones  grow,  and  acquire  soli- 
dity, from  the  centre  to  the  circumference.  Those  of  the  skull 
meet  at  their  edges,  their  fibres  cross  and  form  the  sutures; 
the  cartilaginous  spaces  {fontanels')  which  were  situated  at  the 
meeting  of  their  edges  and  angles  disappear.  The  urine  con- 
tains exceedingly  little  phosphate  of  lime,  that  salt  being  entire- 
ly taken  up  in  the  solidification  of  the  bones.  About  the  middle 
of  the  second  year,  these  have  already  acquired  substance  and 
solidity  enough  to  support  the  weight  of  the  body;  the  child  can 
stand  and  walk.  Before  this  time,  it  would  be  dangerous  for 
him  to  try  it:  the  pillars  of  support,  yet  too  flexible,  would  yield 
under  the  burthen,  and  bend  permanently  in  different  directions. 
It  is  towards  the  head,  that  the  vital  motions  tend  in  infancy: 
accordingly,  this  part  is  the  principal  seat  of  the  affections  pe- 


ON  AGES. 


574 

culiar  to  this  age,  affections  in  which  it  is  often  of  use  to  procure 
local  evacuations. 

The  organs  of  the  senses,  open  to  all  sorts  of  impressions, 
receive  them  with  ease;  but  if,  in  early  infancy,  sensation  is 
easy,  it  is  very  transient;  no  doubt  from  the  want  of  consistence 
in  the  cerebral  ftrgan.  As  it  grows  older,  the  mobility  of  the 
child  is  lessened,  without  diminution  of  susceptibility;  and  it  is 
during  the  years  that  precede  the  boisterous  season  of  puberty, 
that  he  enjoys,  in  the  highest  degree,  the  faculty  of  recalling 
things  that  have  affected  him,  that  his  mem  .ry  is  most  distinct 
and  extended;  but  soon  overpowered  by  imagination,  roused 
up  by  the  powerful  re- action  of  the  sexual  organs  on  the  brain, 
it  ceases  to  have  the  same  exactness. 

CCXXVII.  Of  puberty.  Scx,  climate,  manner  of  life,  have 
great  influence  on  the  earlier  or  later  manifestation  of  the  phe- 
nomena of  puberty.  Women  reach  it  one  or  two  years  before 
men:  the  inhabitants  of  southern,  long  before  those  of  northern 
countries.  Thus,  in  the  hottest  climates  of  Africa,  Asia,  and 
America,  girls  arrive  at  puberty  at  ten,  even  at  nine  years  old, 
but  in  France,  not  till  twelve,  fourteen,  or  fifteen;  whilst  in 
Sweden,  Russia,  and  Denmark,  the  menstrual  discharge,  the 
most  characteristic  mark  of  puberty,  is  from  two  to  three  years 
later. 

The  male  is  known  to  be  capable  of  generation,  and  that  he 
begins  to  live  the  life  of  the  species,  by  the  emission  of  prolific 
semen,  and  the  change  of  voice,  which  becomes  fuller,  more 
grave,  and  sonorous:  the  chin  becomes  covered  with  beard,  the 
genitals  with  hair,  and  they  attain  rapidly  their  full  size.  The 
whole  body  grows;  the  general  characters  which  distinguish  the 
two  sexes,  and  which  are  so  obscure,  before  puberty,  that  they 
may  often  be  mistaken,  become  very  decided,  and  can  no  longer 
be  confounded. 

all  these  signs  of  strength  and  virility,  woman,  urged  by 
desires  which  may  be  termed  wants,  recognizes  the  being  capa- 
ble of  gratifying  them.  The  change  of  voice  is  the  most  certain 
of  the  indications  of  male  puberty.  It  depends,  as  the  following 
observations  show,  on  the  development  of  the  vocal  organs, 
which  constantly  accompanies  that  of  the  sexual  parts. 


ON  AGES. 


575 

CCXXVIII.  A boy,  aged  fourteen,  died  in  the  year  VII.  at 
the  Hospital  of  la  Charite.  On  opening  the  larynx,  I was  sur- 
prised to  see  it  so  small;  and  especially  the  glottis,  whigh  was 
not  above  five  lines  in  its  antero-posterior  diameter,  and  about 
a line  and  a half  in  its  transverse  diameter,  where  its  dimen- 
sions are  greatest;  an  observation  that  must  not  be  omitted,  is, 
that  he  was  very  tall;  but  that  the  development  of  the  genital 
organs  was  as  backward  as  of  the  vocal.  I have  repeated  the 
same  observation  on  subjects  further  from  the  age  of  puberty'; 
have  extended  my  researches  to  those  who  had  passed  it,  and  I 
have  obtained  as  a general  result,  that  between  the  larynx  and 
the  glottis  of  a child  of  three  or  of  twelve,  the  difference  of  size 
is  very  inconsiderable,  and  cannot  be  estimated  b\'  the  height  of 
the  figure: — 

That,  at  the  epoch  of  puberty,  the  organ  of  the  voice  enlarges 
rapidly,  and  that  in  less  than  a year,  the  opening  of  the  glottis 
increases,  in  the  proportion  of  five  to  ten,  that  its  extent  is  thus 
doubled  both  in  length  and  breadth. 

That  these  changes  are  less  remarkable  in  women,  whose 
glottis  increases,  in  the  proportion  only  of  about  five  to  seven; 
that  in  this  respect,  they  still  resemble  children,  as  the  tone  of 
their  voice  would  lead  us  to  suppose. 

These  differences,  in  the  size  of  the  glottis,  account  for  the 
danger  which,  in  children,  accompanies  the  croup.  For,  sup- 
pose an  opening  of  a line  and  a half  in  width,  of  which  the 
edges  are  covered  with  a membrane  of  coagulable  lymph,  the 
opening  will  be  entirely  stopped:  it  would  be  only  narrowed  if 
its  width  were  double;  a sufficient  space  would  remain  free  for 
the  passage  of  the  air.  This  supposition,  which  I have  em- 
ployed to  make  myself  understood,  is  only  the  expression  of  the 
truth,  since  anatomical  inspection  shows  that  the  glottis,  in 
adults,  is  double  the  size  it  is  before  puberty. 

CCXXIX.  Menstruation,  The  symptoms  by  which  puberty 
is  known,  in  women,  are  not  less  remarkable.  The  swelling  of 
the  genital  organs  straitens  the  opening  of  the  canals  that  make 
part  of  them.  The  breasts  become  enlarged,  and  form,  at  the 
fore  part  of  the  thorax,  marked  projections.  Further,  there 
comes  on  a discharge  of  blood,  which  takes  place  every  month, 
from  the  vessels  of  the  womb,  and  which  is  known  by  the  name 


ON  AGES. 


576 

of  the  menstrual  discharge,  or  menses.  This  periodical  evacua- 
tion declares  itself,  in  most  women,  by  all  the  s\  mptoms  that 
indicate  fulness  of  blood,  as  spontaneous  lassitude,  heat,  and 
flushings  in  the  face,  and  by  others  which  show  a direction  of 
the  humours  towards  the  uterus,  and  a local  plethora  of  that 
organ,  as  pains  m the  kidneys,  and  a certain  itching  of  the  parts. 
The  first  eruption  puts  an  end  to  this  state;  which,  in  many, 
may  be  considered  as  a real  disease.  A pure  red  blood  flows  in 
more  or  less  abundance,  for  some  days;  the  general  heaviness 
goes  off  and  the  woman  feels  hersell  relieved. 

I shaii  not  now  speak  of  the  many  deviations  incident  to  the 
menstrual  discharge,  and  which  must  be  considered  as  real  dis- 
eases. Thus,  the  uterine  discharge  has  been  known  to  be  sup- 
plied by  bleeding  from  the  nose,  bsemoptysis,  melaena,  some- 
times by  unusual  evacuations  of  blood,  from  the  eyes,  ears,  the 
fore-finger,  from  ulcerated  surfaces  over  different  parts  of  the 
body. 

It  is  easily  conceived,  that  the  different  parts  of  the  sanguine- 
ous system  may  supply  each  others  place,  and  that  the  bloody 
secretion,  in  which  menstruation  consists,  in  failure  of  the  inter- 
nal surface  of  the  uterus,  may  be  carried  on  by  another  part, 
equally  provided  with  capillary  vessels:  but  that  similar  devia- 
tions ma)r  take  place  for  the  fluids  secreted  by  the  conglomerate 
glands,  as  urine,  bile,  saliva,  is  difficult  to  believe,  notwithstand- 
ing the  many  testimonies  and  authorities  that  may  be  brought 
in  support  of  this  opinion. 

The  fluids  are  not  in  existence  before  the  work  of  secretion; 
the  urine,  retained  in  the  bladder  and  in  the  ureters,  the  bile 
stopped  in  the  gall-bladder  and  the  hepatic  ducts,  after  it  has 
been  prepared  by  the  peculiar  action  of  the  liver,  ma\,  it  is  true, 
from  absorption,  by  the  lymphatic  vessels,  be  carried  into  the 
blood,  and  produce  there  a diseased  urinary  or  bilious  diathe- 
sis; occasion  an  irritation  and  derangement,  after  which,  the 
humour  of  the  cutaneous  perspiration,  and  of  the  sweat,  and  the 
saliva  itself  will  exhibit  some  of  the  qualities  of  the  humour  re- 
tained, and  introduced  bj'  the  absorbents  into  the  circulation. 
The  blood,  contaminated  by  the  admixture  of  a certain  quantity 
of  urine,  may  purify  itself  by  various  emunctories,  by  urinous 
vomitings  and  sweats;  but  that  urine  may,  like  the  menstrual 


ON  AGES. 


577 

blood,  come  out  at  the  eyes,  the  ears,  or  the  navel,  except  in 
case  of  urinary  umbilical  fistula;  that  one  whose  urinary  dis- 
charge, by  the  urethra,  is  not  interrupted,  may  spontaneously 
vomit  it,  is  what  no  man  who  has  any  sound  notions  on  phy- 
siology will  believe;  and  yet  it  is  related,  with  full  details,  in  a 
late  work,  where  these  errors  are  found,  in  the  midst  of  many 
interesting  researches,  on  various  points  of  physiological  che- 
mistry. I have  seen  myself  the  woman,  whose  urine  has  been 
so  well  analysed  by  Dr.  Nysten,  when  the  clinical  professor  of 
medicine,  at  Paris,  obliged  her  to  submit  to  a severe  but  neces- 
sary examination,  and  I am  astonished  that  well-informed  men 
should  so  long  have  given  credit  to  such  gross  impostures.  The 
reader  will,  I hope,  excuse  this  long  digression,  for  the  sake  of 
its  importance.  Literary  criticism  is  now  carried  on  with  such 
partially,  that  no  journalist,  in  praising  justly  what  is  praise- 
worthy, in  the  valuable  work  of  Dr.  Nysten,  has  pointed  out 
the  imposture  of  which  he  was  the  dupe. 

At  first  irregular,  the  menstrual  discharge  assumes  regularity, 
is  repeated  every  month,  and  lasts  from  two  days  to  a week, 
with  evacuation  of  from  three  ounces  to  a pound  of  blood, 
every  time.  Women  of  sanguine  temperament,  robust  and  libi- 
dinous, are  those  whose  menses  last  longest,  and  flow  most 
copiously.  The  blood  is  arterial,  red,  and  has  not,  in  a healthy 
woman,  any  of  the  pernicious  qualities  which  have  been  ascrib- 
ed to  it. 

During  the  whole  time  of  menstruation,  women  are  weaker, 
more  delicate,  more  susceptible  of  impressions;  all  their  organs 
partake  more  or  less,  in  the  affection  of  the  uterus;  and  it  is  not 
difficult  to  an  observer,  of  any  practice,  to  discern  this  state, 
not  merely  by  the  pulse,  but  by  the  change  of  the  countenance 
and  tone  of  the  voice.  Women  then  require  very  careful  ma- 
nagement. An  improper  blood  letting,  a purge,  or  any  other 
remedy  untimely  administered,  may  suppress  the  discharge, 
and  occasion  the  most  serious  aflections.  Climate  evidently 
influences  the  duration  and  quantity  of  the  discharge;  since,  in 
Africa,  it  flows  almost  continually;  whilst  in  Lapland,  it  takes 
place  only  two  or  three  times  a year. 

I shall  not  dwell  upon  the  different  explanations  that  have 
been  given  of  this  phenomenon.  Some  have  ascribed  it  to  the 

4 D 


578 


ON  AGES. 


oblique  position  of  the  uterus,  without  considering,  that  upon 
their  principle,  menstruation  should  take  place  from  the  Soles 
of  the  feet.  Richard  Mead  believe  that  it  depended  on  the 
influence  of  the  moon  over  the  female  system;  but  why  is  it  not 
then  subjected  to  the  lunar  phases?  Those  who  have  found  the 
cause  of  it  in  plethora,  general  or  local,  have,  if  we  admit  their 
explanation,  only  changed  the  difficulty;  for  then,  we  must  ask 
what  are  the  causes  of  this  plethora?  But,  if  this  opinion  had 
any  ground,  nervous  women,  with  a small  quantity  of  blood  in 
their  system,  ought  not  to  menstruate;  and  yet  they  do  so, 
plentifully.  Must  we  ascribe  menstruation  to  an  acquired  habit? 

Is  the  problem  resolved,  by  saying  that  all  the  secretory 
organs  of  women  are  too  weak  to  evacuate  the  superfluity  of 
humours,  which  would  require  for  them  a new  emunctory? 
But  is  not  this  taking  the  effect  for  the  cause?  Does  not  this 
smaller  quantity  of  fluids,  proceeding  from  the  blood,  arise 
from  the  purification  which  the  blood  undergoes  in  the  uterus? 
Let  it  be  remarked,  in  the  mean  time,  that  this  periodical  dis- 
charge seems  to  exempt  the  sex  from  many  inconveniences, 
from  which  ours  suffers;  such  as  gout,  stone  and  gravel,  so 
unfrequent  with  them,  and  so  common  with  us.  Nor  can  we 
avoid  recognizing,  in  this  discharge,  a utility  relative  to  con- 
ception: does  it  not  seem  to  dispose  the  uterus  to  that  func- 
tion?* (CCIV).  Was  it  not  requisite  that  this  organ  should  be 
accustomed  to  receive  a great  quantity  of  blood,  that  pregnancy, 
which  calls  for  this  afflux,  might  not  be  injured,  by  bringing  on 
a sudden  change  in  the  system,  and  the  whole  of  the  vital  func- 
tions. 

Menstruation  is  suspended  during  pregnancy;  it  is  so  during 
the  first  months  of  suckling;  though  this  rule  admits  of  many 
exceptions.  Its  cessation,  in  our  climate,  is  from  the  fortieth  to 
fiftieth  year;  some  times  before,  seldom  later:  though  I have 
now  before  me  the  instance  of  a woman  of  seventy,  who  has  not 
yet  ceased  to  menstruate;  a fact,  which,  after  all,  is  nothing 
more  surprising,  than  that  of  menstruation  beginning  at  an 
early  period  of  life.  When  menstruation  ceases,  the  breasts 
collapse,  plumpness  goes  off  and  the  skin  shrivels,  and  loses  it 
softness,  colour,  and  suppleness.  This  cessation  is  the  cause  of 

♦ The  greater  part  of  female  quadrupeds  have  the  parts  of  generation  bathed 
in  a reddish  lymph,  during  the  time  of  being  in  heat. 


ON  AGES. 


579 

% great  many  diseases  which  break  out,  at  this  season  of  life, 
called  the  turn  of  life,  and  are  fatal  to  many  women:  but  then, 
it  is  observed,  that  when  this  period  is  past,  their  life  is  more 
secure,  with  more  hope  of  prolonging  it,  than  a man  has  at  the 
sanfe  age. 

CCXXX.  Of  manhood.  To  youth  succeeds  manhood:  which 
may  be  considered  as  beginning  from  the  twenty-first  to  the 
twenty-fifth  year.  Then,  all  increase  of  the  body,  in  height,  is 
at  an  end.  The  processes  are  completely  united  to  the  body  of 
the  bones.  But  still,  growth  goes  on  in  other  dimensions.  All 
the  organs  acquire  remarkable  hardness,  solidity,  and  consist- 
ency. It  is  the  same  with  the  intellectual  and  moral  faculties. 
To  the  empire  of  imagination,  succeeds  that  of  judgment.  Man 
is  capable  of  fulfilling  all  the  duties  of  family  and  society.  This 
period  of  life,  to  which  we  give  the  name  of  mature  age,  ex- 
tends to  the  fiftieth  or  the  fifty-fifth  year  for  men:  it  scarcely 
goes  beyond  the  forty-fifth  for  women,  with  whom  it  begins 
also  a little  sooner.  During  this  long  interval,  men  enjoy  the 
whole  plenitude  of  their  existence. 

Although,  in  general,  it  is  not  difficult  to  distinguish,  at  first 
sight,  a man  of  twenty-five,  from  one  of  fifty,  the  differences 
which  mark  them,  depending  on  the  quantity  and  colour  of 
their  hair,  and  on  their  muscular  strength,  are  neither  many 
nor  very  essential. 

Let  us  avail  ourselves  of  this  age,  during  which  the  charac- 
ters of  the  human  species,  merely  sketched,  in  childhood  and 
youth,  take  a more  defined  and  lasting  form,  to  trace  the  fea- 
tures of  individuals  and  of  races. 

CCXXX  1.  Of  temperaments  and  idiosyncrasies.  We  give  the 
name  of  temperaments  to  certain  physical  and  moral  differences 
in  men,  which  depend  on  the  various  proportions  and  relations 
among  the  parts  that  make  up  their  organization,  as  well  as 
upon  different  degrees  in  the  relative  energy  of  certain  organs. 
There  is,  besides,  in  each  individual,  a mode  of  existence  which 
distinguishes  his  temperament  from  that  of  any  other,  to  whom, 
however,  he  may  bear  great  resemblance.  We  express  by  the 
term  idiosyncrasy.^  these  individual  temperaments,  the  know- 
ledge of  which  is  of  no  small  importance  in  the  practice  of 
medicine. 


ON  TEMPERAMENTS. 


S80 

The  predominance  of  any  particular  system  of  organs,  modi- 
fies the  whole  economy,  impresses  striking  differences  on  the 
results  of  the  organization,  and  has  no  less  influence  on  the 
moral  and  intellectual,  than  on  the  physical  faculties.  This 
predominance  establishes  the  temperament;  it  is  the  cause,  and 
constitutes  its  essence. 

If  the  heart  and  the  vessels  which  carry  the  blood,  through 
every  part,  are  of  predominant  activity,  the  pulse  will  be  sharp, 
frequent,  regular,  the  complexion  ruddy,  the  countenance  ani- 
mated, the  shape  good,  the  forms  softened  though  distinct,  the 
flesh  of  tolerable  consistence,  moderate  plumpness,  the  hair  fair 
and  inclining  to  chesnut;  the  nervous  susceptibility  will  be 
lively,  and  attended  with  rapid  successibility,  that  is  to  say, 
that  being  easily  affected  by  the  impressions  of  outward  objects, 
men  of  this  temperament  will  pass  rapidly  from  one  idea  to 
another;  conception  will  be  quick,  memory  prompt,  the  imagina- 
nation  lively;  they'  will  be  addicted  to  the  pleasures  of  the  table 
and  of  love;  w’ill  enjoy  a health  seldom  interrupted  by  disease; 
and  all  their  diseases,  and  these  slight,  modified  by  the  tem- 
perament, will  have  their  seat  principally'  in  the  circulatory' 
system  (injlammatory  fever^  or  angeio-tenique;  phlegmasia; 
acute  hamorrhage;')  and  will  terminate,  when  moderate,  by  the 
mere  force  of  nature,  and  require  the  use  of  the  remedies,  call- 
ed antiphlogistic,  among  which  bleeding  is  the  chief.  The 
ancients  applied  the  name  of  sanguine  to  this  disposition  of 
body;  they  considered  it  as  produced  by  the  combination  of 
warmth  and  moisture,  and  had  very  correctly  perceived  that  it 
existed  in  the  young  of  both  sexes,  was  heightened  by  the 
spring,  the  season  which  has  been  justly  compared  to  youth, 
calling  that  age  the  spring  time  of  life. 

That  the  specific  characters  of  the  temperament  I have  just 
described,  may  show  themselves,  in  all  their  truth,  it  is  requi- 
site that  the  moderate  development  of  the  lymphatic  system, 
concide  with  the  energy  of  the  sanguineous  system,  so  that 
these  two  sects  of  vascular  organs  may'  be  in  true  equipoise. 
The  physical  traits  of  this  temperament  are  to  be  found  in  the 
statues  of  Antinous  and  the  Apollo  of  Belvedere.  Its  moral 
physiognomy  is  drawn  in  the  lives  of  Mark  Antony'  and  Alci- 
biades.  In  Bacchus  are  found  both  the  forms  and  the  character. 


ON  TEMPERAMENTS. 


581 

But  why  seek  amongst  the  illustrious  men  of  antiquity,  or 
among  its  gods,  the  model  of  the  temperament  I have  been 
describing,  whilst  it  is  so  easy  to  find  it  among  the  moderns? 
No  one,  in  my  opinion,  exhibits  a more  perfect  type  of  it  than 
the  Marshal  Duke  of  Richelieu,  that  man,  so  amiable,  fortu- 
nate and  brave  in  war,  light  and  inconstant,  to  the  end  of  his 
long  and  brilliant  career.* 

Inconstancy  and  levity  are,  in  fact,  the  chief  attribute  of  men 
of  this  temperament:  excessive  variety  appears  to  be,  to  them, 
a necessity  as  much  as  an  enjoyment;  good,  generous,  feeling, 
quick,  impassioned,  delicate  in  love,  but  fickle,  disgust,  in  them, 
follows  close  upon  enjoyment:  meditating  desertion,  in  the 
midst  of  the  most  intoxicated  caresses,  they  make  their  escape 
from  beauty,  at  the  very  moment  she  thought  to  have  bound 
them  by  indissoluble  chains.f  In  vain  he  whom  nature  has 
endowed  with  a sanguine  temperament,  will  think  to  renounce 
the  pleasures  of  the  senses,  to  take  fixed  and  lasting  likings,  to 
attain,  by  profound  meditation,  to  the  most  abstract  truths; 
mastered  by  his  physical  dispositions,  he  will  be  forever  driven 
back  to  the  pleasures  from  which  he  flies,  to  the  inconstancy 
which  is  his  lot;  more  fitted  to  the  brilliant  products  of  wit, 
than  the  sublime  conceptions  of  genius.j:  His  blood,  which  a 
vast  lung  impregnates,  plentifully,  with  atmospherical  oxygen, 
flows  freely  in  very  dilatable  canals,  and  this  facility  in  the  dis- 
tribution and  course  of  the  humours  is,  at  once,  the  cause  and 
the  image  of  the  happy  dispositions  of  his  mind. 

* See  his  Memoirs,  6 vols.  8vo. 

Voltaire  has  painted  his  character,  with  superior  ability,  in  many  verses 
addressed  to  him. 

Rival  du  conquerant  de  I’Inde, 

Tu  hois,  tu  plais,  tu  combats,  8ic. 

t The  history  of  Henry  IV.  of  Lewis  XIV.  of  Reg'nard,  and  of  Mirabeau, 
proves  that,  to  the  extreme  love  of  pleasure,  sanguine  men  join,  when  cir- 
cumstances require  it,  great  elevation  of  thought  and  character;  and  call  bring 
into  action  the  highest  talents,  in  every  department. 

t I have  just  met,  in  a gazette,  with  an  assertion  at  least  singular.  All  the 
•world  knows,  says  the  journalist,  that  Newton  was  sanguine,  and  this  proves 
clearly,  he  adds,  that  temperaments  have  no  influence  on  the  intellectual 
powers.  I would  ask  the  journalist  where  he  has  discovered  that  Newton  was 
sanguine.  The  few  details  which  biographers  have  preserved  on  the  physical 
temperament  of  this  illustrious  philosopher,  lead  us  to  believe  that  his  tempera- 


ON  TEMPERAMENTS 


582 

CCXXXII.  If  men  of  this  temperament  apply  themselves, 
from  circumstances,  to  labours  which  greatly  exert  the  organs 
of  motion,  the  muscles,  plentifully  supplied  with  nourishment 
and  disposed  to  acquire  a development  proportioned  to  that  of 
the  sanguinous  system,  increase  in  bulk:  the  sanguineous  tem- 
perament undergoes  a great  modification;  and  there  results  from 
it  the  muscular  or  athletic  temperament,  conspicuous  by  all  the 
outward  signs  of  vigour  and  strength.  The  head  is  very  small, 
the  neck  sunk,  especially  backward,  the  shoulders  broad,  the 
chest  large,  the  haunches  solid,  the  intervals  of  the  muscles 
deeply  marked. 

The  hands,  the  feet,  the  knees,  all  the  articulations  not 
covered  by  muscles,  seem  very  small,  the  tendons  are  marked 
through  the  skin  which  covers  them;  the  susceptibility  is  not 
great:  feeling  dull  and  difficult  to  rouse,  the  athlete  surmounts 
all  resistance,  when  he  has  once  broken  from  his  habitual  tran- 
quillity. The  Farnese  Hercules  exhibits  the  model  of  the 
physical  attributes  of  this  particular  constitution  of  body,  and 
what  fabulous  antiquity  relates  of  the  exploits  of  this  dcmi-god, 
gives  us  the  idea  of  the  moral  dispositions  that  accompany  it. 
In  the  history  of  his  twelve  labours,  without  calculation,  with- 
out reflection,  and  as  by  instinct,  we  see  him  courageous, 
because  he  is  strong,  seeking  obstacles  to  conquer  them,  certain 
of  overwhelming  whatever  resists  him:  but  joining  to  such 
strength  so  little  subtlety,  that  he  is  cheated  by  all  the  kings  he 
serves,  and  all  the  women  he  loves.  It  would  be  difficult  to  find 
in  history  the  example  of  a man  who  has  combined,  with  the 
physical  powers  which  this  temperament  implies,  distinguished 
strength  of  the  intellectual  faculties.  For  excelling  in  the  fine 
arts  and  in  the  sciences,  there  is  need  of  exquisite  sensibility,  a 
condition  absolutely  at  variance  with  much  development  of  the 
muscular  masses. 

CCXXXIII.  If  sensibility,  which  is  vivid  and  easily  ex- 
cited, can  dwell  long  upon  one  object;  if  the  pulse  is  strong, 

ment  was  the  melancholic,  which  is  very  frequently  met  with  in  England.  I will 
not  dare  to  pronounce  absolutely,  on  subjects  on  which  we  can  attain  only  a 
certain  degree  of  probability;  but  if  Newton  had  been  sanguine,  he  would  not 
have  carried  his  maidenhead  with  him  to  the  grave,  at  the  age  of  fourscore, 
as  it  was  affirmed  he  did. 


ON  TEMPERAMENTS, 


583 

hard,  and  frequent,  the  sub-cutaneous  veins  prominent,  the  skin 
of  a brown,  inclining  towards  yellow,  the  hair  black,  moderate 
fulness  of  flesh,  but  firm,  the  muscles  marked,  the  forms  harshly 
expressed;  the  passions  will  be  violent,  the  movements  of  the 
soul  often  abrupt  and  impetuous,  the  character  firm  and  inflexi- 
ble. Bold  in  the  conception  of  a project,  constant  and  indefati- 
gable in  its  execution,  it  is  among  men  of  this  temperament  we 
find  those  who  in  different  ages  have  governed  the  destinies  of 
the  world;  full  of  courage,  of  boldness  and  activity,  all  have 
signalised  themselves  by  great  virtues  or  great  crimes,  have 
been  the  terror  or  admiration  of  the  universe.  Such  were  Alex- 
ander and  Julius  Caesar,  Brutus,  Mahomet,  Charles  XII.,  the 
Czar  Peter,  Cromwell,  Sixtus  V.,  Cardinal  Richelieu. 

As  love  in  the  sanguine,  ambition  is  in  the  bilious  the  govern- 
ing passion.  Observe  a man,  who,  born  of  an  obscure  family, 
long  vegetates  in  the  lower  ranks:  great  shocks  agitate  and  over- 
throw empires:  actor,  at  first  secondary,  of  these  great  revolu- 
tions, which  are  to  change  its  destiny,  the  ambitious  hides  from 
all  his  designs,  and,  by  degrees,  raises  himself  to  the  sovereign 
power,  employing  to  preserve  it  the  same  address  with  which 
he  possessed  himself  of  it.  This  is,  in  two  words,  the  history  of 
Cromwell,  and  of  all  usurpers.* 

To  attain  to  results  of  such  importance,  the  profoundest  dis- 
simulation, and  the  most'obstinate  constancy,  are  equally  neces- 
sary; these  are,  further,  the  most  eminent  qualities  of  the  bilious. 
No  one  ever  combined  them  in  higher  perfection,  than  that 
famous  Pope,  who  slowly  travelling  on  towards  the  pontificate, 
went  for  twenty  years,  stooping,  and  talking  for  ever  of  his  ap- 
proaching death,  and  who,  at  once  proudly  rearing  himself,  cries 
out  “ I am  Pope!”f  petrifying  with  astonishment  and  mortifica- 
tion, those  whom  his  artifice  had  deceived  into  his  party. 

Such  too  was  Cardinal  Richelieu,  who  raised  himself  to  a 
rank  so  near  to  the  highest,  and  was  able  to  maintain  himself  in 
it;  feared  by  a king  whose  authority  he  established,  hated  by 
the  great,  whose  power  he  destroyed,  haughty  and  implacable 
towards  his  enemies,  ambitious  of  every  sort  of  glory,  Stc.j: 

* Vie  d’  Olivier  Cromwell,  par  Jeudy  Dugour,  2 vols.  18mo. 

f Fie  de  Sixte  ^uint,  2 vol.  in  12. 

4 See  his  character  drawn,  with  as  much  truth  as  eloquence,  by  Thomas,  in 
the  last  edition  of  his  Essai  sur  let  Eloget. 


ON  TEMPERAMENTS. 


584 

The  historians  of  the  time  inform  us,  that  this  celebrated 
minister  showed  all  the  customary  signs  of  the  bilious  tempera- 
ment. Gourville  tells  us  that  he  was  all  his  life,  subject  to  a 
very  troublesome  haemorrhoidal  discharge.* 

This  temperament  is  further  characterized  by  the  premature 
development  of  the  moral  faculties.  Scarcely  past  their  youth, 
the  men  I have  named  projected  and  carried  into  execution, 
enterprises  which  would  have  been  sufficient  for  their  fame.  An 
excessive  development  of  the  liver,  a remarkable  superabun- 
dance of  the  biliary  juices,  most  commonly  accompanying  this 
constitution  of  body,  in  which  the  vascular  sanguineous  system 
enjoys  the  greatest  energy,  to  the  prejudice  of  the  cellular  and 
lymphatic  system,  the  ancients  gave  it  the  name  of  bilious.  The 
diseases  to  which  those  distinguished  by  it  are  subject,  involve 
in  fact,  either  as  their  principal  characteristic,  or  as  accessary 
circumstances,  or  as  complication,  the  derangement  of  the  ac- 
tion of  the  hepatic  organs,  joined  to  changes  of  composition  in 
the  bile.  Among  the  remedies  directed  against  these  sort  of 
diseases,  evacuants,  and  especially  emetics,  are  the  best. 

If  all  the  characteristics  assigned  to  the  bilious  temperament 
are  carried  to  the  highest  degree  of  intensity,  and  to  this  state 
is  added  great  susceptibility,  men  are  irrascible,  impetuous, 
violent,  on  the  lightest  occasions.  Such,  Homer  describes  Achil- 
les, and  some  others  of  his  heroes. 

CCXXXIV.  When,  to  the  bilious  temperament,  is  added 
diseased  obstruction  of  any  one  of  the  organs  of  the  abdomen, 
or  derangement  of  the  functions  of  the  nervous  system,  so  that 
the  vital  functions  are  feebly'  or  irregularly  performed,  the  skin 
takes  a deeper  hue,  the  look  becomes  uneasy  and  gloomy,  the 
bowels  sluggish,  all  the  excretions  difficult:  the  pulse  hard  and 
habitually  contracted  (serre^.  The  general  uneasiness  affects  the 
mind;  the  imagination  becomes  gloomy,  the  disposition  suspi- 
cious; the  exceedingly  multiplied  varieties  of  this  temperament, 
called  by  the  ancients  the  melancholic.,  the  diversity  of  accidents 
that  may  bring  it  on,  such  as  hereditary  disease,  long  grief,  ex- 
cessive study,  the  abuse  of  pleasures,  &c.  justify  the  opinion 
which  Clerc  has  proposed,  in  his  natural  history  of  man,  in  a 


f Memoires  de  Gourville. 


ON  TEMPERAMENTS. 


585 

state  of  disease,  where  he  considers  the  melancholic  tempera- 
ment less  as  a primitive  and  natural  constitution,  than  as  a dis- 
eased affection  hereditary  or  acquired.  The  characters  of  Lewis 
XI.  and  Tiberius,  leave  nothing  wanting  for  the  moral  deter- 
mination of  this  temperament.  Read,  in  the  Memoirs  of  Philip 
de  Commines,  and  in  the  Annals  of  Tacitus,  the  history  of 
these  two  tyrants;  fearful,  perfidious,  mistrustful,  suspicious, 
seeking  solitude  by  instinct,  and  polluting  it  by  all  the  acts  of 
the  most  savage  atrocity,  and  the  most  ungoverned  debauch. 
Distrust  and  fearfulness,  joined  to  all  the  disorders  of  imagi- 
nation, compose  the  moral  character  of  this  temperament.  The 
passage  in  which  Tacitus  paints  the  artful  conduct  of  Tiberius, 
when  he  refuses  the  empire,  offered  him  after  the  death  of 
Augustus,  may  be  given  as  the  most  perfect  modtel  of  it.  Versa; 
inde  ad  Tiberium  preces,  £sfc.  Corn.  Tacit.  Annal.  lib.  i. 

As  Professor  Pinel  very  justly  observes,  in  his  treatise  on 
insanity,  the  history  of  men  celebrated  in  the  sciences,  letters, 
and  arts,  has  shown  us  the  melancholic  under  a different  light: 
endowed  with  exquisite  feeling,  and  the  finest  perception;  de- 
voured with  an  ardent  enthusiasm  for  the  beautiful,  capable  of 
realizing  it  in  rich  conceptions,  living  with  men  in  a state  of  re- 
serve bordering  upon  distrust,  analyzing  with  care,  all  their 
actions,  catching  in  sentiment  its  most  delicate  shades,  but  ready 
in  unfavourable  interpretations,  and  seeing  all  things  through 
the  dingy  glass  of  melancholy. 

It  is  extremely  difficult  to  delineate  this  temperament  in  a 
general  or  abstract  manner.  Though  the  ground-work  of  the 
picture  remains  always  the  same,  its  numerous  circumstances 
give  room  for  an  infinite  number  of  variations.  It  is  better, 
therefore,  to  have  recourse  to  the  lives  of  illustrious  men,  who 
have  exhibited  it  in  all  its  force.  Tasso,  Pascal,  J.  J.  Rousseau, 
Gilbert,  Zimmerman,  are  remarkable,  among  many  others,  and 
deserve,  by  their  just  celebrity,  to  fix  our  consideration.  The 
first,  born  in  the  happy  climate  of  Italy,  proscribed  and  unhappy 
from  his  childhood,  author,  at  twenty-two  years  old,  of  the 
finest  epic  poem  the  moderns  can  boast  of,  seized  in  the  midst 
of  the  enjoyments  of  premature  glory,  with  the  most  violent  and 
most  inauspicious  love  for  the  sister  of  the  Duke  of  Ferrara,  at 
whose  court  he  lived;  an  extravagant  passion,  which  was  the 

4 £ 


ON  TEMPERAMENTS. 


586 

pretext  of  the  most  cruel  persecutions,  and  which  followed  him 
to  his  death;  which  took  place  towards  the  thirty-second  year 
of  his  age,  on  the  eve  of  a triumphal  pomp,  which  was  prepared 
for  him  in  the  capitol. 

The  author  of  the  Provincial  Letters,  and  of  the  Thoughts, 
enjoying,  like  Tasso,  a premature  celebrity,  almost  on  quitting 
childhood  was  led  to  melancholy;  not  like  him,  by  the  crosses 
of  unhappy  love,  but  by  a violent  and  overpowering  terror, 
which  left,  in  his  imagination,  the  sight  of  a gulf  for  ever  open 
at  his  side;  an  illusion  which  left  him  only  at  his  death,  eight 
years  after  the  accident.* 

No  one,  perhaps,  has  ever  shown  the  melancholic  tempera- 
ment, in  a higher  degree  of  energy,  than  the  philosopher  of 
Geneva.  To  be.  convinced  of  it,  it  is  enough  to  read,  with  atten- 
tion, certain  passages  of  his  immortal  works,  and  especially  the 
two  last  parts  of  his  Confessions,  and  the  Reveries  in  the  Soli- 
tary Walker;  tormented  with  continual  distrusts  and  fears,  his 
fruitful  imagination  represents  to  him  all  men  as  enemies.  If  you 
believe  him,  the  whole  human  race  is  in  league  to  do  him  mis- 
chief: “ king's  and  nations  have  conspired  together^  against  the 
son  of  a poor  watch-maker  f children  and  invalids  are  brought  in 
to  execute  these  dreadful  plots.  But  let  us  leave  him  to  speak 
for  himself,  the  most  eloquent  and  most  unfortunate  man  of  the 
eighteenth  century:  “ Here  then  I am,  alone  upon  the  earth, 
without  brother,  neighbour,  friend,  without  society  but  myself; 
the  most  sociable  and  the  most  loving  of  men,  has  been  pro- 
scribed by  them  wdth  unanimous  consent.”  This  is  the  begin- 
ning of  the  first  walk;  further  on  he  adds,  “ Could  I believe  that 
I should  be  held,  without,  the  smallest  doubt,  for  a monster,  a 
poisoner,  an  assassin;  that  I should  become  the  horror  of  the  hu- 
man race,  and  the  game  of  the  rabble;  that  all  the  salutation  of 
those  that  passed  by  me,  would  be  to  spit  upon  me;  that  a whole 
generation  would  amuse  itself,  tvith  unanimous  consent,  in  bury- 
ing me  alive?”  It  is  idle  to  multiply  quotations,  in  speaking  of 
the  works  of  a philosopher,  who,  in  spite  of  his  errors,  will  for 
ever  be  the  delight  of  all  those  who  love  to  read  and  to  think. 

The  history  of  J.  J.  Rousseau,  like  that  of  all  the  melancho- 

* He  died  at  59.  See  his  life  by  Condorcet. 


ON  TEMPERAMENTS. 


587 

lies  who  have  distinguished  themselves  in  literature,  shows  us 
genius  struggling  with  misfortune;  a strong  soul  lodged  in  a 
feeble  bodj,  at  first  gentle,  affectionate,  open,  and  tender,  soured 
by  the  sense  of  an  unhappy  condition,  and  of  the  injustice  of 
men.  Till  the  time  when,  impelled  by  the  desire  of  fame, 
Rousseau  sprang  forward  in  the  careeV  of  letters,  we  see  him 
endowed  with  a sanguine  temperament;  acting  with  all  the 
qualities  belonging  to  it;  gentle,  loving,  generous,  feeling, 
though  Inconstant;  his  fertile  imagination  shows  him  nothing 
but  gay  images,  and  in  this  illusion  of  happiness,  he  lives  on 
agreeable  chimeras;  but  gradually  undeceived  by  the  hard  les- 
sons of  experience,  afflicted,  in  the  depth  of  his  heart,  with  his 
own  wretchedness,  and  the  wrongs  of  his  fellow  creatures, 
his  bodily  vigour  wastes  and  decays;  with  it  his  moral  nature 
changes,  and  he  may  be  referred  to  as  the  most  striking  proof 
of  the  reciprocal  influence  of  the  moral  on  the  physical,  and  the 
physical  on  the  moral  part  of  our  being.*  His  history  is  a proof, 
beyond  replj?,  that  the  melancholic  temperament  is  less  a pecu- 
liar constitution  of  the  body,  than  a real  disease,  of  which  the 
degrees  may  infinitely  vary,  from  a mere  originality  of  charac- 
ter, to  the  most  decided  mania. 

Gilbert  arrives  at  Paris,  with  the  germs  of  talents  fitted  for 
that  great  theatre.  Poor  and  rebuffed  by  those  on  whom  he  had 

* I have  no  doubt  that  tlie  influence  of  the  physical  organization  on  the  intel- 
lectual faculties  is  so  decided,  that  we  may  regard  as  possible  the  solution  of 
the  following  problem,  analogous  to  that  with  which  Condillac  concludes  his 
work  on  the  origin  of  human  knowledge. 

The  physical  man  being  given,  to  determine  the  character  and  extent  of  his  capa- 
city, and  to  assign,  consequently,  not  only  the  talents  he  possesses,  but  those  he  is 
capable  of  acquiring. 

The  profound  meditation  of  the  work  of  Galen  {quod  animi  snores  corporis 
temperasnenta  sequantiir;)  the  perusal  of  Plutarch’s  lives  of  Illustrious  Men, 
and  of  the  other  biographers  and  historians  of  ancient  and  morlern  times;  of 
the  Eulogies  of  Fontenelle,  Thomas,  D’Alembert,  Condorcet,  Vicq-d’Azyr, 
&c.,  and  the  study  of  the  medico-philosophical  works  of  Haller,  Cullen,  Caba- 
nis,  Pinel,  Halle,  who  have  modified  and  enriched  the  ancient  doctrine  of  tem- 
peraments, will  be  of  great  avail  in  the  seai’ch  of  this  solution.  “ Philosophy,” 
cries  an  eloquent  writer,  in  the  noble  enthusiasm  which  seizes  him  at  the 
sight  of  the  riches  accumulated  by  Fontana,  in  the  anatomical  museum  at 
Florence,  “ Philosophy  has  been  in  the  wrong,  not  to  descend  more  deeply 
into  physical  man;  there  it  is  that  the  moral  man  lies  concealed;  the  outward 
man  is  only  the  shell  of  the  man  within.” — Dupaty,  33d  letter  on  Italy. 


ON  TEMPERAMENTS. 


588 

built  his  hopes,  he  mixes  in  the  ranks  of  their  detractors,  and 
soon  signalizes  himself,  among  the  most  formidable,  by  a 
vigour  worthy  of  a better  cause.  Persecuted,  without  respite, 
by  want,  the  mortifying  sight  of  the  happiness  which  his  ene- 
mies enjoyed,  and  to  which  he  believed  himself  called,  led  him 
on  to  a state  ol  perfect  madness.  He  believes  himself  perse- 
cuted by  the  philosophers,  who  want  to  rob  him  of  his  papers; 
to  save  them  from  their  imagined  rapacity,  he  locks  his  manu- 
scripts in  a press,  and  swallows  the  key.  It  sticks  at  the  entrance 
of  the  larynx,  stops  the  passage  of  the  air,  and  suffocates  the 
patient,  who  dies,  at  the  Hotel-Dieu,  after  three  days  of  the 
most  cruel  sufferings.* 

Zimmerman,  early  exhausted  by  study,  already  a physician 
of  celebrity,  at  an  early  age  lives  in  solitude,  with  an  ardent 
imagination,  joined  to  the  highest  susceptibility;  abandoned  to 
himself,  devoured  with  the  thirst  of  glory,  he  gives  himself  up 
to  labour  in  excess,  publishes  his  Treatise  on  Experience,  and 
the  work  on  Solitude,  so  deeply  imbued  with  the  colouring  of 
his  soul.  Forced  from  the  solitude  he  loves,  he  carries  into  the 
courts  to  which  his  reputation  calls  him,  an  inexhaustible  store 
of  bitterness  and  sadness,  which  political  events  supervening, 
brought  to  greater  excess;  arrived  at  length  gradually  at  the  last 
term  of  hypochondria,  he  dies  beset  with  pusillanimous  fears, 
worthy  of  all  eulogium  and  all  regret.f 

* His  life  would  have  been  preserved,  if  the  cause  of  his  illness  had  been 
understood,  which  he  indicated  himself  by  repeating,  “the  key  chokes 
me.”  His  state  of  madness  made  this  pass  for  the  words  of  a madman;  but  on 
opening  the  body,  the  key  was  found,  of  which  the  ward  part  was  fixed  at  the 
entrance  of  the  larynx;  it  would  have  been  easy  to  draw  it  out,  by  putting  a 
finger  down  the  throat. 

This  unfortunate  young  man  expressed,  a few  days  before  his  death,  the 
melancholy  state  of  his  soul,  in  stanzas  most  touchingly  mournful;  this  is  one, 
full  of  interest  and  simplicity: 

Au  banquet  de  la  vie  infortune  convive, 

Je  parus  un  jour,  et  je  meurs; 

Je  meurs  et  sur  ma  tombe  ou  lentement  j’arrive 
* Nul  ne  viendra  verser  des  pleurs. 

f See  his  Eulogium  by  Tissot;  it  is  at  the  beginning  of  the  last  edition  of  the 
Treatise  on  Experience  in  Medicine.  It  there  appears  how  deeply  he  was  af- 
fected by  the  French  revolution,  of  which  he  foresaw,  with  a sort  of  prophetic 
spirit,  the  disastrous  consequences  to  his  own  country. 


ON  TEMPERAMENTS. 


589 

CCXXXV.  If  the  proportion  of  the  fluids  to  the  solids  is 
too  greaty  this  superabundance  of  the  humours,  which  is  con- 
stantly in  favour  of  the  lymphatic  system,  gives  to  the  whole 
body  considerable  bulk,  determined  by  the  development  and. 
repletion  of  the  cellular  tissue.  The  flesh  is  soft,  the  counte- 
nance pale,  the  hair  fair,  the  pulse  weak,  slow,  and  soft,  the 
forms  rounded  and  without  expression,  all  the  vital'  actions 
more  or  less  languid,  the  memory  treacherous,  the  attention  not 
continuous.  Men  of  this  temperament,  to  which  the  ancients 
gave  the  name  of  phuitous^  and  which  we  should  call  lymphatic^ 
because  it  depends  really  on  the  excessive  development  of  this 
system,  have,  in  general,  an  insurmountable  inclination  to  sloth, 
averse  alike  to  labours  of  the  mind  and  body;  accordingly,  wo 
are  not  to  wonder,  if  we  find  none  of  them  among  Plutarch’s 
illustrious  men.  Little  fitted  for  business,  they  have  never 
exercised  great  empire  over  their  fellow  creatures,  they  have 
never  changed  the  face  of  the  globe,  by  their  negociations  or 
their  conquests.  One  of  the  friends  of  Cicero,  Pomponius 
Atticus,  whose  history  Cornelius  Nepos  has  left  us,  conciliating 
to  himself  all  the  factions  which  tore  the  Roman  republic  to 
pieces,  in  the  civil  wars  of  Caesar  and  Pompey,  may  be  given 
as  the  model  of  it.  Among  the  moderns,  the  easy  Michel 
Montaigne,  all  whose  passions  were  so  moderate,  who  reasoned 
on  every  thing,  even  on  feeling,  was  truly  pituitous.  But,  in 
him,  the  predominance  of  the  lymphatic  system  was  not  carried 
so  far,  but  that  he  joined  to  it  a good  deal  of  nervous  suscepti- 
bility. In  the  pituitous,  from  the  excess  of  watery  particles  in 
the  fluid  which  should  carry  every  where  heat  and  life,  the  cir- 
culation goes  on  slowly,  the  imagination  is  weak,  the  passions 
languid;  and,  from  this  moderation  of  the  desires,  spring,  on 
many  occasions,  those  virtues  of  temperament^  which,  to  say  it, 
by  the  by,  should  not  supply  their  possessors  with  matter  of 
quite  so  much  self-complacency. 

CCXXXVI.  This  property  by  which  we  are,  more  or  less, 
sensible  to  impressions  on  our  organs,  weak  in  the  pituitous, 
almost  nothing  in  athletes,  moderate  in  those  of  sanguine  tem- 
perament, rather  quick  in  the  bilious,  constitutes,  by  its  excess, 
the  nervous  temperament;  seldom  natural  or  primitive,  but 
commonly  acquired,  and  depending  on  a sedentary  and  too 


ON  TEMPERAMENTS. 


590 

inactive  life,  on  habitual  indulgence  in  sensuality,  on  the  mor- 
bid action  of  the  brain,  promoted  by  reading  works  of  imagina- 
tion, &c.  This  temperament  shows  itself  in  the  emaciation,  in 
the  smallness  of  the  muscles,  soft,  and  as  it  were,  in  an  atrophy, 
in  the  vivacity  of  the  sensations,  in  the  suddenness  and  muta- 
bility of  the  determinations  and  judgments.  Nervous  women, 
whose  wills  are  absolute,  but  changeable,  with  excess  of  sensi- 
bility, frequently  exhibit  it  with  all  these  characteristics.  Often, 
however,  they  have  something  of  good  looks,  the  extreme  pre- 
ponderance of  the  nervous  system  still  allowing  a moderate 
development  of  the  lymphatic.  Spasmodic  affections  are  not 
uncommon  among  them;  and  when  it  is  observed  that,  on  the 
other  hand,  the  athletic  constitution,  directly  opposite  to  the 
nervous  temperament,  predisposes  to  tetanus,  may  we  not  say^, 
that  the  two  extremes  meet,  or  produce  the  same  effects? 

Antispasmodics  are  employed,  with  success,  in  the  treatment 
of  their  diseases,  which  partake  always,  more  or  less,  of  the 
temperament.  Stimulants,  on  the  contrary,  are  very  suitable  to 
those  of  a pituitous  or  lymphatic  temperament.  The  neivous 
temperament,  like  the  melancholic,  is  not  so  much  a natural 
constitution  of  the  body,  as  the  first  stage  of  a disease.  This 
temperament,  like  the  nervous  affections  which  are  the  result  of 
it,  has  never  shown  itself  but  among  societies  brought  to  that 
state  of  civilization,  in  which  man  is  the  farthest  possible  from 
nature.  The  Roman  ladies  became  subject  to  nervous  affections, 
only  in  consequence  of  those  depraved  manners  which  marked 
the  decline  of  the  Empire.  These  affections  were  extremely 
common  in  France,  during  the  eighteenth  century,  and  in  the 
times  preceding  the  fall  of  the  monarchy.  Of  that  epoch,  are 
the  works  of  Wytt,  Raulin,  Lorrey,  Pomme,  &c.  on  nervous 
affections.  Tronchin,  a Genevese  physician,  acquired  great 
W’ealth  and  reputation  by  the  treatment  of  these  diseases.  His 
whole  secret  consisted  in  exercising  to  fatigue,  women  ha- 
bitually inactive,  keeping  up  their  strength,  at  the  same  time, 
by  simple,  healthy,  and  plentiful  food.  The  two  most  re- 
markable men  of  the  eighteenth  century.  Voltaire  and  the 
great  Frederick,  may  be  given  as  instances  of  the  nervous 
temperament;  and  the  history  of  their  brilliant  and  agitated 


ON  TEMPERAMENTS.  59 

life,  shows,  sufficfently,  how  much  the  circumstances  in  which 
they  lived,  contributed  to  develop  their  native  dispositions. 

I shall  finish  this  article  on  temperaments  by  observing,  that 
in  truth,  we  bring  with  us  into  the  world  these  particular  dispo- 
sitions of  body;  but  that  from  education,  manner  of  life,  climate, 
acquired  habits,  they  are  altered,  or  altogether  changed.  Fur- 
ther, it  is  exceedingly  rare  to  find  individuals,  who  show,  in 
their  purity,  the  characters  assigned  to  the  different  tempera- 
ments: the  descriptions  given  are  drawn  from  an  assemblage  of 
individuals,  much  resembling  one  another.  Their  characters 
are  pure  abstractions,  which  it  is  difficult  to  realize,  because  all 
men  are  at  once  sanguine  and  bilious,  sanguine  and  lymphatic, 
See.  In  this  instance,  physiologists  have  imitated  the  artist,  who 
united  in  the  image  of  the  goddess  of  beauty,  a thousand  per- 
fections which  he  saw  separate  in  the  most  beautiful  women  of 
Greece.* 

It  is  an  observation  that  the  sanguine  constitution  is  directly 
opposed  to  the  melancholic,  and  never  combines  with  it;  that  it 
is  the  same  with  the  bilious  and  lymphatic:  though  it  may  hap- 
pen that  a man,  sanguine  in  youth,  shall  become  melancholic 
after  a lapse  of  time;  for,  as  I have  said  before,  man  never  re- 
mains such  as  he  came  from  the  hands  of  nature;  fashioned  by 
all  that  surrounds  him,  his  physical  qualities,  at  different  periods 
of  his  life,  are  as  much  changed  as  his  character. 

Of  all  the  causes  that  can  modify  the  nature  of  man,  and 
which  will  even  change  completely  the  nature  of  his  native 
dispositions,  there  is  none  more  powerful  than  the  long . con- 
tinued action  of  air,  water,  and  residence,  as  the  father  of 
medicine  has  said.  Climate,  in  fact,  exerts  upon  the  tempera- 
ment the  most  marked  influence.  Thus,  the  bilious  temperament 
is  that  of  the  greater  part  of  the  inhabitants  of  southern  coun- 
tries; the  sanguine  that  of  the  nations  of  the  north;  the  lympha- 
tic constitution  reigns,  on  the  contrary,  in  cold  and  moist  coun- 
tries, like  Holland.  We  have  seen  in  what  manner  the  athletic, 
melancholic,  and  nervous  temperament  grows  out  of  our  habits 

* It  is  thus  that,  in  the  arts  of  imitation,  the  ideal  grows  up;  now,  from  the 
exaggeration  of  features;  now,  from  the  union  of  qualities  which  nature  has 
produced  separate. 


ON  TEMPERAMENTS. 


592 

of  life:  let  us  now  endeavour  to  appreciate  the  power  of  climate 
over  the  constitution  of  the  greater  part  of  mankind. 

It  is  known,  that  the  influence  of  heat,  in  the  production  of 
bilious  diseases,  is  such,  that  after  having  been  extremely  pre- 
valent during  the  summer,  they  disappear,  or  at  least  become 
much  less  frequent  m the  autumn.  A notable  increase  of  per- 
spiration never  takes  place  without  a proportioned  diminution 
in  the  quantity  of  the  liquids  with  which  the  alimentar)’  surfaces 
are  moistened.  Now,  when  the  gastric  juice  is  less  abundant, 
the  bile,  being  mixed  with  a smaller  quantity  of  serosities,  irri- 
tates more  the  intestinal  surfaces;  the  digestive  powers  languish, 
and  there  is  an  approaching  disposition  to  meningo-gastnc 
fevers.  The  same  influences,  continued  during  the  whole  year 
in  hot  countries,  must  necessarily  increase,  with  the  activity  of 
the  biliary  system,  its  power  over  the  other  parts  of  the  eco- 
nomy, and  thus  establish  a predominance  of  the  bilious  consti- 
tution, through  both  health  and  disease. 

As  for  the  sanguine  temperament,  so  generally  met  with 
among  northern  nations,  it  is  the  necessary  consequence  of  the 
continual  and  very  energetic  re-action  of  the  powers  of  circula- 
tion, against  the  effects  of  external  cold.  It  is  only  by  the  con- 
stant activity  of  the  heart  and  vessels,  that  calorification  can  be 
effected  with  the  necessary  vigour.  Now,  the  effects  of  this  re- 
doubled action  are  the  same  to  the  organs  of  circulation,  as  to 
the  muscles  under  the  influence  of  volition:  in  both,  exertioij^ 
increases  the  power  of  the  organs  exerted.  The  diseases  of  the 
nations  of  the  north,  analogous  to  their  temperament,  have,  for 
the  most  part,  their  seat  in  the  system  of  sanguineous  vessels: 
their  character  is  eminently  inflammatory. 

Lastly,  the  lymphatic  state  of  nations,  living  under  a moist 
climate,  is  nothing  more  surprising  than  the  aqueous  nature  of 
plants,  and  small  density  of  the  wood,  in  trees  growing  under 
the  influence  of  a foggy  air.  Animal  bodies,  like  plants,  absorb 
by  their  surfaces,  and  become  gorged  with  humours,  the  excess 
of  which  always  produces  a remarkable  slackening  of  activity  in 
the  organic  motions. 

The  temperament  of  which  the  character  is  the  predominance 
of  one  organ  or  system  of  organs,  departs  from  that  ideal  state, 
where  all  the  powers  are  reciprocally  balanced,  so  as  to  exhibit 


ON  TEMPERATURES. 


593 


in  the  living  economy,  a perfect  equilibrium.  This  state,  which 
has  perhaps  never  been  found,  but  in  the  imaginations  of  phy- 
siologists,, and  which  was  called  by  the  ancients,  the  temperate 
temperament,  temperamentum  temperatum,  being  taken  as  the 
type  of  health,  it  follows  that  this  temperament  is  already  a step 
made  towards  disease.  Yet  the  action  of  the  predominant  sys- 
tem is  not  in  such  excess  as  to  destroy  all  equilibrium,  and  im- 
pede the  action  of  life;  but  let  the  constitutional  dispositions  be 
much  increased,  the  disease  is  begun,  and  this  transition  takes 
place  in  the  conversion  of  the  lymphatic  temperament  into 
scrophula.*  In  the  scrophulous  constitution,  there  is,  at  once, 
activity  of  the  absorbing  mouths,  great  facility  of  absorption, 
inertness  of  the  vessels  and  lymphatic  glands,  weakness  of  the 
absorbents,  and  consequently  a thickening  and  stagnation  of  the 
liquids  absorbed.  The  same  thing  is  seen  in  the  lymphatic  tem- 
perament, characterized  by  the  activity  of  the  inhaling  mouths, 
and  the  debility  of  the  lymphatic  system,  as  Professor  Cabanis 
was  aware,t  when  he  refuted  the  opinion  of  those  who  ascribe  the 
lymphatic  temperament  to  the  excess  of  activity  in  the  absorbent 
system,  though  the  only  part  of  this  system  really  quickened,  is 
that  which  immediately  performs  absorption,  whilst  the  rest  is 
in  a state  of  perfect  atony. 

CCXXXVII.  Varieties  of  the  human  species.  The  power  of 
producing,  by  copulation,  like  individuals,  is  considered,  by 
naturalists,  as  the  most  certain  test  for  fixing  the  species  in  red 
and  warm-blooded  animals.  This  power  of  self-perpetuation, 
by  a constant  succession  of  similar  beings,  is  found  in  all  the 
races  composing  the  human  species,  however^dilferent  in  colour, 
structure,  and  manner  of  life.  Men,  then,  are  but  one  species, 
and  the  difference  that  appears  in  them,  according  to  the  region 
of  the  globe  they  inhabit,  can  only  constitute  varieties  or  races. 
I admit,  with  M.  Lacepede,  the  worthy  continuator  of  Buffon, 
four  principal  races  of  the  human  species,  which  I shall  call, 

* See  Nnsographie  Chirurgicale,  tome  I.  for  the  history  of  scrophulous  tilcers, 
from  which  this  paragraph  is  taken  entire.  The  author,  in  that  work,  has 
aimed  at  introducing  physiology  into  surgery,  till  then  exclusively  abandoned 
to  explanations  of  the  grossest  mechanism. 

f Of  the  relations  of  the  physical  and  moral  man,  by  G.  Cabanis,  Senator, 
Professor  in  the  School  of  Medicine,  in  Paris,  &c. 

4 F 


594 


ON  THE  HUMAN  RACE. 


like  him,  the  European,  Arab,  the  Mogul,  the  Negro,  and  the 
Hyperborean.  We  might  add  a fifth,  of  the  American,  were  it 
not  most  probable,  that  the  new  continent  is  peopled  by  inhabi- 
tants, who,  coming  from  the  old,  either  by  land  in  the  austral 
hemisphere,  or  along  the  immense  Archipelago  of  the  Pacific 
Ocean,  have  been  altered  by  the  influence  of  that  climate,  and 
the  yet  virgin  soil,  so  that  they  are  to  be  regarded  less  as  a 
distinct  race  than  a simple  variety. 

There  is,  in  truth,  this  difference  between  varieties  and  races, 
that,  in  these  last,  there  are  implied  modifications  more  pro- 
found, more  essential  differences,  changes  not  confined  to  the 
surface,  but  extending  to  the  very  structure  of  the  body;  where- 
as, to  make  a variety,  nothing  more  is  needed,  than  the  superficial 
influence  of  climate  on  the  integuments  which  it  colours,  and 
on  the  hairs  which  it  makes  longer  or  shorter,  lank  or  curled, 
hard  or  soft.  An  Abyssinian,  scorched  by  the  heat  of  an  almost 
tropical  sky,  is  as  black  as  the  negro  under  the  equator:  yet  they 
are  by  no  means  of  one  race,  since  the  Abyssinian,  a negro 
only  in  colour,  resembles  the  European  in  the  cast  of  his  face, 
and  the  proportions  of  all  his  parts. 

The  characteristics  of  the  European  Arab  race,  which  takes  in 
the  inhabitants,  not  of  Europe  only,  but  of  Egypt  also,  Arabia, 
Syria,  Barbary,  and  Ethiopia,  are  an  oval,  or  almost  oval 
face,  in  the  vertical  direction,  a long  nose,  a prominent  skull, 
long  and  commonly  lank  hair,  a skin  more  or  less  white.  These 
fundamental  characteristics  are  no  where  more  decided  than  in 
the  north  of  Europe.  The  inhabitants  of  Sweden,  Finland,  and 
Poland,  give  the  prototype  of  the  race:  their  stature  is  tall,  their 
skin  of  perfect  whiteness,  their  hair  long,  lank,  and  of  a light 
colour;  the  colour  of  the  iris  generally  bluish.  The  Russians,  the 
English,  the  Danes,  the  Germans,  are  already  somewhat  re- 
moved from  this  primordial  type:  the  colour  of  their  skin  is  of 
less  pure  white,  their  hair  of  a deeper  hue.  The  French  seem 
to  stand  midway  betwixt  the  nations  of  the  North  and  those  of 
the  South  of  Europe.  Their  skin  is  shaded  with  a deeper  dye, 
their  hair  less  straight,  and  more  of  a chesnut  and  brown 
colour.  The  Spaniards,  the  Italians,  the  Greeks,  the  European 
Turks,  and  the  Portuguese,  are  browner,  their  hair,  in  general, 
black.  Lastly,  the  Arabs,  the  Moors,  and  the  Abyssinians,  have 
hair,  in  some  measure,  black  and  crisp,  the  skin  tawny,  and 


ON  THE  HUMAN  RACE. 


595 

might  serve  for  the  step  from  the  European  Arab  to  the  Negro 
race:  which  is,  however,  distinguished  from  them,  by  the  flat- 
tening of  .the  forehead,  the  smallness  of  the  skull,  the  slope  'of 
the  line  measuring  the  height  of  the  face,  the  thickness  of  the 
lips,  the  projection  of  the  malar  bones,  and  further,  by  a darker 
skin,  thicker,  greasy,  and,  as  it  were,  oily,  as  well  as  by  shorter, 
finer,  curly,  and  woolly  hair. 

The  Mogul  race  has  the  forehead  flat,  the  skull  jutting  but 
little,  the  eyes  looking  rather  obliquely  outwards;  the  cheeks 
are  prominent,  and  the  oval  of  the  face,  instead  of  extending 
from  the  forehead  to  the  chin,  is  drawn  between  the  two  malar 
bones.  The  Chinese,  the  Tartars,  the  inhabitants  of  the  Penin- 
sula, of  the  Ganges,  and  of  the  other  countries  of  India,  of 
Tonquin,  Cochin-China,  Japan,  of  the  kingdom  of  Siam,  &c. 
compose  this  race,  more  numerous  than  all  the  others,  and  ap- 
parently more  ancient  also,  which  is  spread  over  a far  greater 
extent  than  the  European  Arab  race,  and  yet  more,  than  the 
Negro  race,  since  it  reaches  from  the  fortieth  to  the  sixtieth 
parallel  of  latitude,  occupying  an  arc  of  the  meridian  of  nearly 
75°,  whilst  that  which  measures  the  countries  of  the  European 
race  is  only  of  50°,  and  the  Negro  race  lying  under  the  equator, 
between  the  tropics  of  Cancer  and  of  Capricorn,  is  bounded 
within  the  limits  of  an  arc  of  from  30  to  35°.* 

The  Hyperborean  race,  situated  in  the  north  of  the  two  con- 
tinents in  the  neighbourhood  of  the  polar  circles,  composed  of 
the  Laplanders,  the  Ostiaks,  the  Samoiedes,  and  the  Green- 
landers, is  characterised  by  a flat  face,  a squat  body,  and  a very 
short  stature.  This  degraded  portion  of  the  human  species 
derives,  evidently,  from  the  climate,  its  distinctive  characteris- 
tics. Striving  for  ever  with  the  inclemency  of  a severe  climate, 
the  destructive  action  of  an  icy  temperature,  nature,  fettered 
in  her  motions,  shrunk  in  her  dimensions,  can  produce  only 
beings  whose  physical  imperfections  explain  their  almost  bar- 
barous condition. 

The  small  progress,  of  the  negroes  in  the  study  of  the  sciences, 
and  in  civilization,  their  decided  taste  and  singular  aptitude  for 
all  the  arts  which  require  more  taste  and  dexterity,  than  un- 
derstanding and  reflection,  as  dancing,  music,  fencing,  See.  the 


* Lacepede,  Geograpbie  Zoologique. 


596 


ON  THE  HUMAN  RACE. 


figure  of  the  head,  which  is  midway  between  that  of  the 
European  and  the  ourang-outang,^  the  existence  of  the  inter- 
maxillary bones,  at  an  age,  when,  with  us,  the  traces  of  their 
separation  are  completely  effaced;  the  high  situation  and  small 
development  of  the  calf  of  the  leg,  have  been  arguments  more 
specious  than  solid  to  those  who  have  endeavoured  to  abase 
this  portion  of  the  human  species  in  order  to  justify  an  iniqui- 
tous traffic,  and  a cruel  tyranny:  reproaches  of  civilized  men, 
which  they  must  wipe  off  by  other  means  than  a presumptuous 
assertion  of  their  own  dignity,  or  a proud  insult  on  the  native 
character  of  those,  whom  they  themselves  have  cast  into  de- 
gradation. 

Without  admitting  this  belief,  which  owes  its  origin  to  a thirst 
of  riches,  w’e  cannot  help  acknowledging  that  the  differences  of 
organization  draw  after  them  a striking  inequality  in  the  deve- 
lopment of  the  moral  and  intellectual  faculties.  This  truth  would 
appear  in  its  full  light  if,  after  summarily  indicating,  as  I have 
just  done,  the  physical  characteristics  of  the  races  of  men,  I could 
unfold  their  moral  differences,  as  real  and  not  less  marked: 
opposing  the  activity,  the  versatility,  the  restlessness  of  the  Eu- 
ropean, to  the  indolence,  the  phlegm,  the  patience  of  the  Asiatic; 
examining  what  is  the  power,  on  the  character  of  nations,  of 
fertility  of  soil,  serenity  of  sky,  the  mildness  of  climate;  showing 
by  what  catenation  of  physical  and  moral  causes,  the  empire 
of  custom  is  so  powerful  over  the  people  of  the  East,  that  we 
find  in  India  and  China  the  same  laws,  manners,  and  religion 
which  prevailed  there  long  before  our  era:  inquiring  by  what 

* The  black  colour  of  the  skin,  in  Negroes,  seems  owing,  as  I have  already 
said,  to  the  scorching  of  the  gelatine,  which  is  the  base  of  the  rete  mucosum 
of  Malpighi.  This  colour,  acquired  in  a long  succession  of  ages,  perpetuated 
and  transmitted  by  generation,  is  become  one  of  the  characteristic  features 
of  the  Negro  race.  M.  Volney,  in  a work  which  should  be  a model  to  all  tra- 
vellers, grounds  on  the  face  of  the  blacks,  a conjecture  as  ingenious  as  it  is 
probable.  He  observes,  that  it  exhibits,  precisely,  that  state  of  contraction 
■which  our  face  takes  wdien  it  is  struck  by  light,  and  a strong  reverberation  of 
heat:  then,  says  this  philosophical  traveller,  the  brow  contracts,  the  cheek- 
bones rise,  the  eye-lid  contracts  and  the  lips  project.  Must  not  this  contrac- 
tion of  the  moveable  part  have  influenced,  in  course  of  time,  the  hai-d  parts, 
aivd  even  moulded  the  structure  of  the  bones?  Voyagt  tn  Syrie  et  en  E^ypte, 
Tom.  I.  p.  70,  3ieme  Edition. 


ON  THE  HUMAN  RACE. 


597 

singularity,  well  worthy  the  meditation  of  philosophers  and 
politicians,  these  laws,  this  worship,  and  these  manners  have 
undergone  no  change,  amidst  the  revolutions  which  have  so 
often  taken  place  among  those  nations,  many  times  conquered 
by  the  warlike  Tartars;  showing  how,  by  the  irresistible 
ascendancy  of  wisdom  and  knowledge,  ignorant  and  ferocious 
conquerors  have  adopted  the  usages  of  the  nations  they  had  sub- 
jugated: and  proving  that  the  stationary  condition  of  the 
sciences  and  arts  among  those  who,  so  long  before  ourselves, 
were  in  possession  of  the  advantages  of  civilized  society,  is 
derived  not  so  much  from  the  imperfection  of  their  organiza- 
tion as  from  the  degrading  yoke  of  a religion  loaded  with 
absurd  practices,  and  which  makes  knowledge  the  exclusive 
birthright  of  a privileged  cast.-*  But  such  an  undertaking, 
besides  exceeding  the  limits  I have  prescribed  myself,  does  not 
belong  directly  to  my  subject. 

The  Albinoes  of  Africa,  the  Cagots  of  the  Pyrenees,  and  the 
Cretins  of  the  Valais,  cannot  be  given  as  varieties  of  the  human 
species.  They  are  infirm,  feeble,  degraded  beings,  incapable  of 
reproducing  an  existence,  which  has  fallen  to  them,  in  the 
midst  of  a healthy,  vigorous,  and  robust  population. 

We  are  not  to  believe  what  some  travellers  have  written  on 
the  existence  of  tribes  of  Giants,  that  have  appeared  on  the 
Magellanic  coasts.  The  Patagonians,  concerning  whose  stature 
there  is  so  little  agreement  in  relations,  are  men  very  well 
formed,  and  whose  stature  does  not  exceed  ours  more  than 
nine  or  ten  inches.  The  Laplanders,  whose  stature  is  the 
smallest,  are  as  much  below,  as  the  Patagonians  are  above;  it 
does  not  exceed  from  four  feet  to  four  and  a half.  In  the  midst  of 
ourselves,  individuals  reach  from  time  to  time,  a stature  suffi- 
cient to  intitle  them  to  the  name  of  giants,  whilst  others,  shrunk 
in  all  their  proportions,  are  a renewal  of  the  pygmies.  Such  was 
Bebe,  the  dwarf  of  Stanislaus,  king  of  Poland;  Goliah,  spoken 

* See,  concerning'  the  religion  of  the  Bramins,  and  the  Indian  customs, 
Raynal’s  Philosopliical  History.  We  must  assign  further  as  a main  cause  of  the 
■want  of  progress  of  the  Indians  and  Chinese,  in  the  arts  and  sciences  sprung 
from  civilization,  the  imperfection  of  their  alphabet,  which,  being  composed 
of  a multitude  of  characters,  which  do  not,  like  ours,  represent  sounds,  but 
ideas.  It  is  no  part  of  my  object  to  show  how  much  signs  so  defective  must 
confine  the  sphere  ajud  fetter  the  combinations  of  the  mind. 


598 


ON  THE  HUMAN  RACE. 


of  in  the  Book  of  Kings,  Ch.  xvii.  v.  4.  the  King  Og,  Dent. 
Ch.  iii.  V.  2.  and  many  others,  whose  stature  varies  from  six  to 
ten  feet  high. 

CCXXXVIII.  Of  old  age  and  decrepitude.  The  human  body 
which,  from  the  twentieth  year  of  life,  ceases  to  grow  in  height, 
increases  in  every  other  dimension,  during  the  twenty  succeeding 
years.  After  this  period,  far  from  growing,  it  begins  to  decay, 
and  loses  daily  a part  of  its  strength.  The  decay  proceeds  at 
the  same  rate  as  the  growth,  and  is  not  more  rapid,  since  man 
requires  from  thirty  to  forty  years  in  reaching  to  his  full  growth, 
and  takes  about  the  same  time  in  his  progress  to  the  grave, 
provided  no  accident  hurries  him  to  an  untimely  end.*  The 
whole  bulk  of  the  body  diminishes,  the  cellular  tissue  becomes 
collapsed,  and  the  skin  wrinkled,  especially  that  of  the  forehead 
and  face.  The  hairs  of  the  head  and  over  the  rest  of  the  body 
turn  grey,  then  white;  the  organic  action  becomes  languid;  the 
fluids  become  more  disposed  to  putrefaction  (Hunter);  hence, 
at  this  period  of  life,  all  diseases  of  debility  are  more  frequent, 
and  attended  with  greater  danger. 

Decay  succeeds  old  age.  The  sensibility  of  the  organs  is 
blunted;  the  physical  and  intellectual  faculties  undergo  a gra- 
dual decay;  man  ceases  to  be  impressed,  in  the  same  manner, 
by  surrounding  bodies.  His  judgments  are  incorrect,  because 
self-love  preventing  him  from  being  aware  of  the  changes  which 
he  has  undergone,  he  is  more  disposed  to  ascribe  to  an  univer- 
sal degeneracy,  the  difference  which  exists  between  the  sensa- 
tions which  he  now  experiences,  and  those  which  he  experienced 
in  his  youth  (laudator  temporis  acti).  The  digestion  is  bad,  the 
pulse  W'eak  and  slow;  absorption  difficult,  from  the  almost  com- 
plete obliteration  of  the  lymphatics  and  the  induration  of  the 
conglobate  glands;  the  secretion  languid  and  nutrition  imper- 
fect. The  old  man  is  slow  in  all  his  actions,  and  stiff  in  all  his 
motions;  his  hair  falls  off,  his  teeth  drop  from  their  sockets,  the 
cartilages  ossify;  the  bones  grow  irregularly  and  become  anchy- 

*The  duration  of  life  ma)'-  be  estimated  by  that  of  the  growth.  A dog 
ceases  to  grow,  at  the  end  of  two  or  three  years,  and  lives  only  ten  or  twelve; 
Man,  whose  growth  requires  a space  of  from  twenty  to  thirty  years,  attains 
to  the  age  of  ninety  or  a hundred.  Fishes  live  several  centuries,  their  develop- 
ment requiring  a considerable  number  of  years. 


ON  OLD  AGE. 


599 

losed,  their  internal  cavity  enlarges;  all  the  organs  become  indu- 
rated, and  the  fibres  dried  and  shrivelled.  The  bones  become 
heavier,  from  the  gradual  accumulation  of  phosphate  of  lime, 
and  if  those  of  the  skull,  as  is  justly  observed  by  Scemmering, 
on  the  contrary,  become  lighter,  it  is  that  they  are,  in  a manner, 
worn  out,  by  the  continued  motions  of  the  brain,  on  their  inter- 
nal surface. 

I he  ossification  of  some  of  the  cartilages,  for  example,  of 
those  of  the  ribs  and  vertebras,  is  productive  of  remarkable  ef- 
fects. The  ribs  becoming  soldered,  in  a manner,  to  the  sternum, 
perform  very  imperfectly,  their  natural  motion  of  elevation  and 
twisting,  (LXXI.)  which  produces  the  enlargement  of  the  chest. 
This  cavity  dilating  less  fully,  the  pulmonary  combinations, 
which  are  the  abundant  sources  of  animal  heat,  take  place  in  a 
less  effectual  manner,  which,  joined  to  a want  of  tone  and  ener- 
gy in  the  lungs,  and  in  all  the  organs,  lowers  the  temperature 
of  old  people,  as  was  observed  by  the  father  of  physic,*  a cir- 
cumstance, however,  which  has  been  denied  by  Dehaen. 

Those  fibro-cartilaginous  laminae,  with  oblique  fibres  crossing 
each  other,  which  unite,  so  firmly,  the  bodies  of  the  vertebrae, 
become  indurated,  dried  and  shrivelled,  sink  under  the  weight 
of  the  body,  and  do  not  recover  their  former  thickness,  so  that 
the  stature  is  really  reduced;  besides,  the  weakened  condition 
of  the  muscles,  which  raise  the  trunk,  makes  the  weight  of  the 
viscera  bend  forward  the  vertebral  column,  whose  different  parts 
may  remain  fixed  in  this  attitude,  so  that  the  whole  column, 
consisting  of  twenty-four  vertebrae,  may  come  to  consist  of  only 
seven  or  eight  distinct  bones.  It  should  not  be  imagined,  how- 
ever, that  all  the  soft  parts  become  more  compact,  for  several, 
as  Haller  observes,  the  muscles,  for  instance,  become  softer,f 
and  seem,  in  losing  a part  of  their  vital  properties,  to  draw 
towards  a speedy  dissolution;  not  that  death  is  entirely  owing 
to  the  accumulation  of  phosphate  of  lime,  which  enters  into  the 
composition  of  all  the  organs,  converts  into  ossific  matter  the 

* Senibus  autem  modicus  est  calor  * * * * frigidum  est  enim  ipsorum  cor- 
pus.— Hippocr.  Aph.  14.  Sect.  2. 

fNon  ergo  in  sola  rigiditate  causam  send  mortis  oportet  ponere;  nam  ex 
defectu  irritabilitatis,  plurimijin  senibus  musculi  languent,  mollesque  pendent. 
— Elementa  Physiol,  torn.  VIII.  4to.  lib.  30. 


ON  OLD  AGE. 


600 

whole  osseous  system,  and  interrupts  the  action  of  the  animal 
machine.  If  this  ossific  matter  invade  every  part  of  the  animal 
system,  it  is  because  the  digestive  powers,  gradually  weakened, 
cease  to  affect,  in  a suitable  manner,  the  alimentary  substances. 
The  exuberance  of  calcareous  salts  is,  therefore,  not  so  much 
the  cause  as  the  effect  of  the  successive  destruction  of  the  vital 
powers. 

The  slowness,  the  rigidity,  and  the  difficulty  of  moving  do 
not  depend  so  much,  as  is  thought,  on  the  induration  of  the 
ligaments  and  other  fibrous  organs;  these  ligaments  become 
softened  and  relaxed,  to  a considerable  degree,  so  that  luxation 
is  more  easily  performed,  after  death,  in  old  people.  In  them, 
likewise,  organs,  which,  in  youth,  have  a degree  of  consistency, 
become  flaccid  and  soft;  this  is  the  case  with  the  heart,  which 
becomes  collapsed  in  old  people,  its  cavities  remaining  entire, 
while,  in  young  persons  and  in  adults,  their  parietes  are  not  in 
close  contact. 

The  brain  becomes  harder  and  firmer,  less  soluble  in  alkalies; 
its  albumen  appears  less  completely  oxydized  than  in  younger 
subjects:  impressions  are  less  easily  made,  and  the  motions  ne- 
cessary to  the  operations  of  the  understanding  are  performed 
with  difficulty.  Hence,  in  decrepitude,  man  returns,  as  far  as 
relates  to  his  intellectual  faculties,  to  a state  of  second  child- 
hood, limited  to  certain  recollections  which  are  at  first  confused, 
and,  in  the  end,  completely  lost,  incapable  of  judgment  or  will, 
or  of  new  impressions;  sleep  resumes  its  influence;  reduced  to 
a mere  vegetative  existence,  he  sleeps  the  greatest  part  of  the 
day,  and  wakens  only  to  satisfy  his  physical  wants,  and  to  take 
food,  which  he  digests  very  imperfectly.  For,  in  the  first  place, 
the  want  of  teeth  prevents  his  being  able  to  divide  sufficiently 
the  different  substances,  and,  in  the  next  place,  the  supply  of 
saliva,  of  gastric  and  intestinal  juices  is  almost  interrupted;  the 
bile  and  other  fluids  are  less  active,  and  the  intestinal  tube  is 
without  energy.  Universal  rigidity  will  be  admitted  as  one  of 
the  principal  causes  of  death,  if  it  be  considered  that  women,  in 
whom  the  organs  are  naturally  softer,  are  longer  in  reaching  that 
state,  are  more  retentive  of  life  th.an  men,  and,  generally,  live  to 
a greater  age. 


ON  DEATH. 


601 

The  body,  therefore,  dies  slowly  and  by  degrees,  says  the 
eloquent  M.  De  Baffon;  life  gradually  becomes  extinguished, 
and  death  is  but  the  last  term  of  this  series  of  degrees,  the  last 
shade  {nuance')  of  life, 

rCXXXIX.  Of  death.  Tong,  in  fact,  before  the  close  of  life, 
man  loses  the  power  of  reproduction;  and,  in  the  course  of  the 
agony  which  serves^as  a passage  between  life  and  death,  the 
organs  ot  sense  first  become  insensible  to  all  sorts  of  impres- 
sions;  the  eyes  grow  dim,  the  cornea  fades,  the  eye-lids  close, 
the  voice  becomes  extinct,  the  limbs  and  the  trunk  motionless; 
yet  the  circulation  and  respiration  continue  to  be  carried  on,  but 
at  last  cease,  first  in  the  vessels  furthest  from  the  heart,  and 
then,  gradually,  in  the  vessels  nearest  that  organ.  Respiration, 
gradually  slackened,  being  entirely  suspended  after  a strong  ex* 
piration,*  the  lungs  no  longer  transmit  the  blood  which  the 
veins  bring,  from  every  quarter,  to  the  heart.  This  fluid  stag- 
nates in  the  right  cavities  of  the  heart,  and  these  die  last,  {ulti- 
mum  mor'iensf^  and  distended  by  the  blood  which  collects  within 
them,  they  attain  a capacity  exceeding  greatly  that  of  the  left 
cavities,  which  are,  to  a certain  degree,  emptied. 

Such  is  the  course  of  natural  death;  the  brain  ceases  to  receive 
from  the  weakened  heart,  a suSicient  quantity  of  blood  to  keep 
up  sensibility;  there  remains  still  some  degree  of  contractility 
in  the  respiratory  muscles;  it  is  soon  exhausted,  however,  and 
the  circulatory  motion  of  the  blood  ceases  with  the  life  of  all 
the  organs,  of  which  this  fluid  is  one  of  the  principal  movers. 

As  to  accidental  death,  it  is  always  determined  by  the  cessa- 
tion of  the  action  of  the  heart  and  brain;  for,  the  death  of  the 
lungs  occasions  that  of  the  whole  body,  only  by  preventing  the 
action  of  the  heart,  by  interrupting  its  influence  on  the  encepha- 
lic organ.  In  natural  death,  therefore,  life  becomes  extinguished 
from  the  circumference  to  the  centre;  in  accidental  death,  on 
the  contrary,  the  centre  is  affected  before  the  extremities. 

Bichat,  in  his  work  entitled,  Recherches  sur  la  vie  et  la  mort^ 
has  given  a very  complete  account  of  the  manner  in  which  the 

* Does  this  last  and  powerful  expiration,  often  attended  by  sighing,  depend 
on  the  spasmodic  contraction  of  the  muscles  of  expiration;  or  rather  does  it 
not  depend  on  the  re-action  of  the  elastic  parts  which  form  the  chest,  a re. 
action  which  suddenly  ceases  to  be  counter-balanced  by  the  vital  properties, 

4 G 


ON  DEATH, 


602 

organs  of  the  animal  economy  cease  to  act  in  articulo  mortis; 
but  like  all  the  other  authors  who  vvent  before  him,  he  has 
limited  his  inquiries  to  certain  functions.  No  one  has  attempted 
to  extend  them  to  the  phenomena  of  the  action  of  the  brain,  nor 
has  any  one  traced  the  order  in  which  the  various  faculties  of 
thought  and  of  sensation  vanish.  I shall  endeavour  faithfully  to 
mention  the  results  of  several  hundred  observations  of  my  own 
on  this  subject. 

The  close  of  life  is  marked  by  phenomena  similar  to  those 
with  which  it  began.  The  circulation  first  manifested  itself,  and 
ceases  last.  The  right  auricle  is  the  part  first  seen  to  pulsate  in 
the  embryo,  and,  in  death,  is  the  last  to  retain  its  motion.  The 
phenomena  of  nutrition  to  which  the  fce  al  existence  is  almost 
entirely  limited,  continue,  even  when  the  organs  destined  to 
establish  a relation  with  the  beings  that  surround  us,  have  long 
been  sunk  into  a slumber  from  which  they  are  never  to  be 
rouzed. 

The  following  is  the  order  in  which  the  intellectual  faculties 
cease  and  are  decomposed."^  Reason,  the  exclusive  attribute  of 
man,  first  forsakes  him.  He  begins  by'  losing  the  faculty  of 
associating  judgments,  and  then  of  comparing,  of  bringing  to- 
gether, and  of  connecting  a number  of  ideas,  so  as  to  judge  of 
their  relations.  The  patient  is  then  said  to  have  lost  his  con- 
sciousness, or  to  be  delirious.  This  delirium  has,  generally,  for 
its  subject,  the  ideas  that  are  most  familiar  to  the  patient,  and 
his  prevailing  passion  is  easily  recognized.  The  miser  talks,  in 
the  most  indiscreet  manner,  of  his  hidden  treasures;  the  unbe- 
liever dies  haunted  by  religious  apprehensions.  Sweet  recollec- 
tions of  a distant  native  land,  then  it  is  that  ye  return  with  your 
all  powerful  energy  and  delight! 

After  reasoning  and  judgment,  the  faculty  of  associating 
ideas  is  next  completely  destroy’ed.  The  same  occurs  iu  faint- 
ing, as  I once  experienced  in  myself;  I was  conversing  with 
one  of  my  friends,  when  I experienced  an  insuperable  difficulty 

* I need  not  inform  the  reader,  that  I am  not  here  speaking  of  the  immor- 
tal soul,  of  that  divine  emanation  which  outlives  matter,  and  which,  freed 
from  our  perisliable  part,  returns  to  the  Almighty.  I am  speaking  merely  of 
the  intellectual  faculties  common  to  man,  and  to  those  animals  which,  like  him, 
are  provided  with  a brain. 


ON  DEATH. 


603 

in  associating  twa  ideas,  from  the  comparison  of  which  I wished 
to  form  a judgment.  Yet  syncope  was  not  complete,  I still  pre- 
served memory  and  the  faculty  of  feeling.  I could  distinctly 
hear  those  about  me  say,  he  is  fainting,  and  exert  themselves 
to  relieve  me  from  this  condition,  which  was  not  without  en- 
joyment. 

The  memory  then  fails.  The  patient  who,  during  the  early 
part  of  his  <lelirium,  recognized  the  persons  about  him,  no 
longer  knows  his  nearest  and  most  intimate  friends. 

At  last,  he  ceases  to  feel,  but  his  senses  vanish  in  succession 
and  in  a determinate  order;  the  taste  and  smell  cease  to  give 
any  sign  of  existence;  the  eyes  become  obscured  by  a dark  and 
gloomy  cloud;  the  ear  is  yet  sensible  to  sound  and  noise,  and 
no  doubt,  it  was,  on  this  account,  that  the  ancients,  to  ascertain 
that  death  had  really  taken  place,  were  in  the  habit  of  calling 
loudly  to  the  deceased. 

A dying  m.an,  though  no  longer  capable  of  smelling,  tasting, 
hearing,  and  seeing,  still  retains -the  sense  of  touch;  he  tosses 
about  m his  bed,  moves  his  arms  in  various  directions,  and  is 
perpetually  changing  his  posture;  he  performs,  as  was  already 
said,  motions  similar  to  those  of  the  foetus  within  the  mother’s 
womb. 

CCXL.  Of  the  period  of  death.  This  period  is  nearly  the 
same  with  all  men,  whether  they  live  near  the  poles,  or  under 
the  equator,  whether  they  live  exclusively  on  animal  or  vegetable 
substances,  whether  they  lead  an  active  life,  or  consume  their 
existence  in  disgraceful  sloth:  few  live  beyond  a hundred  years. 
There  are,  however,  cases  of  men  who  have  lived  far  beyond 
that  period;  as,  for  example,  those  men  mentioned  in  the  phi- 
losophical transactions,  one  of  whom  lived  to  a hundred  and 
sixty-five. 

Few  men,  however,  attain  a hundred  years;  and  death,  even 
when  natural,  overtakes  us  from  the  age  of  seventy-five  to  a 
hundred. 

Difference  of  climate,  though  producing  no  difference  in  the 
duration  of  life,  has,  however,  a remarkable  influence  on  rapi- 
dity of  growth.  Puberty,  manhood,  and  old  age,  come  on  much 
ooner  in  warm  climates,  than  in  northern  countries;  but  this 
premature  development  which  shortens  the  duration  of  the 


ON  DEATH. 


604 

periods  of  life,  augments,  in  the  same  proportion,  that  of  old 
age. 

It  is,  however,  difficult  to  say,  at  what  precise  period  old 
age  begins.  Is  it  towards  the  fortieth  year,  when  the  body 
begins  to  decrease  and  to  decay?  Can  the  change  of  the  colour 
of  the  hair  be  considered  as  the  certain  sign  of  old  age?  We 
daily  see  young  men  with  gray  hair.  May  we  determine  its  ac- 
cession, b}’^  the  cessation  of  the  functions  of  generation  and 
the  incapacity  of  reproduction?  Fecundity,  whose  term  is  so 
easily  determined  in  woman  by  the  cessation  of  the  menses,  is, 
in  man,  very  equivocal;  the  emission  of  seminal  fluid  is  an 
uncertain  sign,  from  the  difficulty  of  distinguishing  the  mucus 
of  the  vesiculse  seminales  and  of  the  prostate,  from  the  truly 
prolific  semen.  Erection  is  likewise  a sign  not  to  be  relied 
upon;  this  state  may  be  occasioned  by  sympathetic  irritation, 
by  the  compression  of  the  bladder,  distended  with  urine,  on 
the  vesiculae  seminales.  It  is  more  difficult  than  is  imagined,  to 
determine,  from  observation,  the  period  at  which,  in  the  human 
species,  the  male  is  entirely  deprived  of  the  power  of  genera- 
tion; and  it  may  be  said  that,  in  establishing  the  period  of  from 
forty-five  to  fifty-five,  as  the  beginning  of  old  age  in  our  climate, 
there  will  be  found  men  arrived  at  that  state,  before  having 
reached  that  age;  as,  on  the  other  hand,  others  will  be  foond 
after  the  age  of  flit) -five,  with  all  the  characters  of  manhood. 
The  climacterical  period  of  sixty-three  is  the  decided  and  con- 
firmed period  of  old  age.  Whatever  regimen  may  have  been 
followed,  man,  at  that  age,  is  truly  old  and  cannot  but  be  aware 
of  it. 

CCXLI.  Of  the  probabilities  of  human  life.  Man  dies  at  all 
ages;  and  if  the  duration  of  his  life  surpass  that  of  the  lower 
animals,  the  great  number  of  diseases  to  which  he  is  liable,  ren- 
ders it  much  more  uncertain,  and  is  the  cause  why  a much 
smaller  number  arrive  at  the  natural  term  of  existence.  It  has 
been  attempted  to  discover  what  are  the  probabilities  of  life, 
that  is,  to  ascertain,  from  observation,  how  long  a man  may 
expect  to  live,  who  has  already  reached  a determinate  age. 
From  late  accurate  observations  of  the  age  at  which  a number 
of  persons  have  died,  and  from  a comparison  of  the  deaths 
with  the  births,  it  has  been  ascertained,  that  about  one  fourth 
of  the  children  that  are  bom,  die  within  the  first  eleven  months 


ON  DEATH. 


605 

of  life;  one  third  before  twenty-three  months;  and  one  half 
before  they  reach  the  eighth  year.  Two  thirds  of  mankind  die 
before  the  thirty-ninth  year,  and  three  fourths  before  the  fifty- 
first;  so  that,  as  Buffon  observes,  of  nine  children  that  are  born, 
only  one  arrives  at  the  age  of  seventy-three;  of  thirty,  only  one 
lives  to  the  age  of  eighty;  while  out  of  two  hundred  and  ninety- 
one,  only  one  lives  to  the  age  of  ninety;  and  in  the  last  place, 
out  of  eleven  thousand  nine  hundred  and  ninety-six,  only  one 
drags  on  a languid  existence  to  the  age  of  a hundred  years. 

The  mean  term  of  life  is,  according  to  the  same  author,  eight 
years,  in  a new  born  child.  As  the  child  grows  older,  his  exis- 
tence becomes  more  secure,  and  after  the  first  year,  he  may 
reasonably  be  expected  to  live  to  the  age  of  thirty-three.  Life 
becomes  gradually  firmer  up  to  the  age  of  seven,  when  the  child, 
after  going  through  the  dangers  of  dentition,  will  probably  live 
forty-two  years  and  three  months.  After  this  period,  the  sum 
of  probabilities  which  had  gradually  increased,  undergoes  a 
progressive  decrease;  so  that  a child  of  fourteen  cannot  expect 
to  live  beyond  thirty-seven  years  and  five  months;  a man  of 
thirty,  twenty-eight  years  more;  and,  in  the  last  place,  a man 
of  eighty-four,  one  year  only.  From  the  eighty-filth  to  the  nine- 
tieth year,  probabilities  remain  stationary,  but  after  this  period, 
existence  is  most  precarious  and  is  painfully  carried  on  to  the 
end.  Such  is  the  result  of  observation,  and  of  calculations  on 
the  diflFerent  degrees  of  probability  of  human  life,  by  Halley, 
Graunt,  Kersboom,  Wargentin,  Simson,  Deparcieux,  Dupre 
de  St.  Maur,  Buffon,  d’Alembert,  Barthez,  and  M.  Mourgues, 
who  has  just  published  his  observations,  collected  at  Montpellier 
in  the  course  of  a great  number  of  years,  and  with  the  most 
scrupulous  accuracy. 

I should  enter  more  fully  into  this  subject,  but  that  it  belongs 
more  to  the  department  of  political  economy  than  to  that  of 
physiology. 

The  calculations  on  the  probabilities  of  human  life,  present 
results  applicable  to  the  generality  of  cases,  since  the  mean  dura- 
tion of  existence  is  nearly  the  same  with  all  men,  in  all  countries 
and  climates.*  The  shepherd  of  the  Pyrenees,  who  lives  happy 

♦ The  researches  of  Sir  John  Sinclair  do  not  disprove  this  statement,  though 
this  author  adheres  faithfully  to  the  practice  generally  adopted  by  his  country- 
men, of  speaking  most  favourably  of  England  and  Scotland.  The  statistical 


606 


ON  DEATH. 


in  the  innocence  of  a pastoral  life,  breathing  the  pure  air  of  his 
mountains,  is,  in  this  respect,  subject  to  ihe  same  laws  as  the 
inhabitant  of  populous  cities,  exposed  to  the  inconveniences  at- 
tending numerous  collections  of  men;  inconveniences,  which 
viewed  in  a philosophical  point  of  view,  or  which  greatly  over- 
rated, have  so  often  furnished  a text  to  the  meditations  of 
philosophy,  and  to  the  idle  declamations  of  - ratory. 

Does  life  experience  a progressive  diminution,  in  proportion 
to  the  duration  of  the  world;  and  to  say  nothing  of  the  time 
preceding  the  flood,  when,  according  to  the  book  of  Genesis, 
men  lived  several  hundred  years,  did  the  men  of  former  times 
live  longer  than  those  of  our  own?  This  is  very  improbable; 
among  the  Egyptians,  the  Hebrews,  the  Greeks,  and  Romans, 
there  were  very^  few  instances  of  persons  living  to  the  age  of  a 
hundred  years,  and  instances  ot  longevity  are  perhaps  more  fre- 
quent among  the  moderns. 

The  art  of  providing  for  the  wants  of  life,  making  daily 
progress,  it  is  very  probable,  that  far  from  being  shortened,  the 
term  of  human  life  may  be  lengthened  a certain  number  of 
years  beyond  its  ordinary  duration.  This  idea  is,  it  is  true,  con- 
trary to  the  commonly  received  opinion  of  the  progressive  de- 
pravity of  mankind  in  all  ages;  but  the  golden  age  never  exist- 
ed, but  in  the  imagination  of  poets;  and  the  daily  complaints  of 
morose  old  age  have  their  origin  in  motives  easily  understood 
by  the  physiologist.  He  whose  sentiment  is  blunted  by  a long 
course  of  years,  is  affected,  in  a very  different  manner,  by  sur- 
rounding objects.  As  to  the  old  man,  flowers  have  lost  their 
scent  and  beauty,  fruits  no  longer  retain  their  flavour.  The 
whole  of  nature  seems  dull  and  colourless.  But  the  cause  of  all 
these  changes  is  within  himself,  every  thing  else  remains  as  it 
was.  Always  equally  fruitful,  nature  exposes  every'  thing  to  the 
action  of  her  inexhaustible  crucible;  maintains  every  thing  in  a 
state  of  everlasting  youth,  and  preserves  a freshness  ever  re- 
newed. Individuals  die,  species  are  renov'ated;  life  every  where 
arises  in  the  midst  of  death.  The  materials  of  organized  bodies, 
enter  into  new  combinations  and  serve  in  forming  new  beings, 
when  life  ceasing  to  animate  those  to  which  they  belonged, 
putrefaction  seizes  upon  them,  and  effects  their  destruction. 

tables  published  in  different  parts  of  Europe,  show  that  the  number  of  people 
v.ho  reach  the  age  of  a hundred  is  equally  great  there. 


ON  PUTREFACTION. 


607 

CCXLII.  Of  putrefaction.  Here  the  history  of  life  ought  to 
terminate;  if,  however,  it  be  considered  that  the  changes  which 
bodies  experience  after  death,  thro\v  a considerable  light  on  its 
means,  its  ends,  and  its  nature,  there  will  be  an  obvious  neces- 
sity for  shortly  inquiring  into  the  different  phenomena  which 
accornpany  the  decomposition  of  animal  substances.  And  this 
investigation  appears  to  me  to  belong  to  the  department  of  phy- 
siology, until  the  aspect  of  the  body  ceases  to  recal  the  idea  of 
its  former  state,  and  until  the  last  lineaments  of  organization  are 
completely  effaced.  As  soon  as  life  forsakes  our  organs,  they 
become  subject  to  the  laws  of  physics,  operating  on  substances 
that  are  not  organized.  An  inward  motion  takes  place  within 
their  substance,  and  their  molecules  have  the  greater  tendency 
to  become  separated  from  one  another,  as  their  composition  is 
more  advanced.  Chemistry  informs  us  that  the  tendency  to  de- 
composition of  bodies  is  in  direct  ratio  to  the  number  of  their 
elements,  and  that  a dead  animal  body  is  capable  of  remaining 
unchanged,  in  proportion  as  its  composition  is  more  simple,  and 
its  constituent  principles  less  numerous  and  less  volatile. 

Before  putrefaction  can  come  on  in  the  human  body,  it  must 
be  entirely  deprived  of  life,  for  the  vital  powers  are  most 
powerfully  antiseptic,  and  one  might  say  that  life  is  a continual 
struggle  against  the  laws  of  physics  and  chemistry.  This  vital 
resistance,  alluded  to  by  the  ancients  when  they  said,  that  the 
laws  of  the  microcosm  were  in  perpetual  opposition  to  those  of 
the  universal  world,  and  that  these  in  the  end  prevailed;  this 
power,  which  is  in  a state  of  perpetual  re-action,  manifests 
itself  in  life:  the  latter,  considering  only  the  results,  might, 
therefore,  be  defined  as  follows:  the  resistance  opposed  by  or- 
ganic bodies  to  the  causes  incesscMly  tending  to  their  destruction. 
By  attending  to  ail  these  phenomena,  it  will  be  seen  that  all  of 
them  tend  to  one  end,  the  preservation  of  the  bod}?^,  and  that 
they  obtain  it,  only  by  keeping  up  a perpetual  struggle  with 
the  laws  which  govern  inorganic  substances. 

It  might  appear  singular,  that  death  should  furnish  a just 
idea  of  life,  did  we  not  know,  that  it  is  by  comparing  that  we 
are  enabled  to  distinguish,  to  judge,  and  to  arrive  at  knowledge. 

Putrefaction  takes  place  and  is  completed,  only  in  substances 
deprived  of  life.  A mortified  limb  loses  its  vitality  before  putre- 
faction comes  on,  and  if  nature  preserve  sufficient  energy  to  re- 


608 


ON  PUTREFACTION. 


aist  this  destructive  process,  she  draws,  by  a line  of  inflammation, 
the  separation  between  the  dead  and  the  living  part.  Life  and 
putrefaction  are,  therefore,  two  absolutely  contradictorv  ideas; 
and  when,  in  some  diseases,  there  is  observed  a tendency  in  the 
solids  and  fluids  to  spontaneous  decomposition,  this  tendency 
to  putrefaction  should  not  be  mistaken  for  putrefaction  itself. 

Several  conditions  are  required  to  enable  putrefaction  to 
affect  the  human  body  after  death.  In  the  first  place,  a mild 
temperature,  that  is,  above  ten  degrees  of  Reaumur’s  thermo- 
meter; in  the  next  place  a certain  degree  of  moisture,  and, 
lastly,  the  presence  of  air.  This  last  condition,  however,  is  not 
so  necessary  as  the  two  former,  since  substances  undergo 
putrefaction  in  a vacuum,  though  more  slowly.  The  air  conse- 
quentlj^  promotes  decomposition,  only  by  carrying  off  the  ele- 
ments which  rise  in  vapours.  On  the  other  hand,  an  icy  cold, 
or  a degree  of  heat  approaching  to  boiling,  prevent  it;  the 
former,  by  condensing  the  parts;  the  second,  by  depriving  them 
of  moisture,  the  complete  absence  of  which,  accounts  for  the 
preservation  of  the  Egyptian  mummies. 

The  phenomena  of  putrefaction,  resulting  from  a series  of  pe- 
culiar attractions,  are  modified  in  various  ways,  according  to  the 
nature  of  the  animal  substances  which  are  subjected  to  it,  to 
the  media  in  w'hich  it  takes  place,  to  the  different  degrees  of 
moisture  and  temperature,  and  even  according  to  its  different 
periods.  Notwithstanding  these  innumerable  varieties,  one  may 
say  that  all  exhale  a certain  cadaverous  smell,  are  softened, 
increase  in  bulk,  acquire  heat,  change  colour,  assume  a green- 
ish, then  a livid  and  dark  brown  colour;  there  are  at  the  same  time 
disengaged,  a great  number  of  gaseous  substances,  of  which 
ammonia  is  the  most  remarkable,  either  from  its  quantity,  or 
from  being  given  out  by  animal  substances,  from  the  moment 
when  decomposition  begins,  to  the  period  of  the  most  complete 
dissolution.  This  gas  produces  the  pungent  and  putrid  smell 
which  exhales  from  dead  bodies. 

Towards  the  termination  of  putrefaction,  there  is  disengaged 
carbonic  acid  gas,  which  combining  with  ammonia,  forms  a fixed 
and  crystallizable  salt.  Besides  these  products,  there  are  given 
out  sulphuretted  and  phosphuretted  hydrogen,  or  combined  with 
azote,  carbonic  acid,  and  all  the  substances  that  may  be  produc|d 


ON  PUTREFACTION. 


609 

by  their  respective  combinations.  In  the  last  place,  animal  sub- 
stances, when  reduced  to  a residue  containing  oils  and  salts  of 
different  kinds,  form  a mould,  from  which  plants  draw  the  prin- 
ciples of  a luxuriant  and  vigorous  vegetation.  The  bones,  those 
least  alterable  parts  of  the  organized  machine,  in  time,  become 
dried  by  the  slow  combustion  of  their  fibrous  part,  and  by  the 
evaporation  of  their  medullary  juices.  At  last,  reduced  to  an 
earthy  skeleton,  they  crumble  into  dust,  and  this  dust  is  dissi- 
pated, on  opening  the  tombs  in  which  they  were  laid. 

Thus,  in  course  of  time,  is  effaced  all  that  could  recalthe  idea 
of  our  physical  existence. 

Putrefaction,  considered  in  a philosophical  point  of  view,  is 
but  a means  employed  by  nature,  to  restore  our  organs,  deprived 
of  life,  to  a more  simple  composition,  in  order  that  their  ele- 
ments may  be  applied  to  new  creations.  (Circulus  ceterni  motics.*') 
Nothing,  therefore,  is  better  proved,  than  the  metempsychosis  of 
matter;!  which  warrants  the  belief  that  this  religious  dogma,  like 
most  of  the  fabulous  worships  and  imaginations  of  antiquity,  is 
but  a veil  ingeniously  thrown  by  philosophy,  between  nature  and 
the  ignorant. 

* Beecher,  Physica  subterranea. 

! Matter  is  eternal,  in  this  sense,  that  the  molecules  of  bodies  merely  pass 
from  the  one  into  the  other;  they  survive  the  destruction,  or  rather  the  disso- 
lution of  organic  and  inorganic  beings,  when  the  former,  ceasing  to  live,  re- 
store to  the  inexhaustible  fund  of  nature,  those  elements  which  she  lends 
without  ever  parting  with  them. 

Mancipio  nulli  datur,  omnibus  usu. 

Lucret.  lib.  III. 


FINIS. 


4 H 


4. 


, ' i,^-.  ; . ')^' 'ft  .),■•  '*<  ■ •'■•■,•  ■» 

f . ' .'  •■  '■  ; , , 


, 'f  .!>  » fi 


ANALYTICAL  INDEX. 


Preface — preliminary  discourse.  Physiology- 
of  Life.  Definition  of  life. 


-the  Science 


§ I.  Of  JVat Ural  Beings. 

They  are  inorganic  or  organized — The  former  are  simple  or 
complex;  the  latter  always  complex,  and  distinguished  into 
vegetable  and  animal.  Reciprocal  dependance  of  all  these  bc“ 
ings,  2. 

§11.  Of  the  Elements  of  Bodies. 

The  elements  of  Bodies.  Their  number  forty-four;  but  it  is 
probable  that  several  appear  to  us  simple,  from  the  imperfection 
of  our  means  of  analysis,  3. 


§ III.  Differences  between  Organized  and  Inorganized  Bodies. 

Differences  between  organized  and  inorganized  bodies,  4. 
Homogeneousness  of  the  latter;  complex  nature  of  the  former; 
necessary  co-existence  of  fluids  and  solids  in  all  organized  and 
living  beings;  simplicity  of  inanimate  matter;  complex  nature 
and  tendency  to  decom.position  of  organized  bodies,  5. 

§ IV.  Differences  between  Animals  and  Plants. 

Differences  between  animals  and  plants,  8.  The  great  distance 
between  the  mineral  and  vegetable  kingdom.  A considerable 
approximation,  on  the  contrary,  between  animals  and  plants,  9. 
Of  all  the  characters  which  mark  the  differences  between  these 
substances,  the  most  remarkable  is  the  presence  of  an  alimen- 
tary tube,  which  is  found  in  every  animal  from  man  down  to  the 
polypus,  9.  In  all  animals,  nutrition  is  performed  by  two  sur- 
faces, especially  by  the  internal;  the  alimentary  canal  is  the  most 


/ 


612 


INDEX. 


essential  part  of  their  body,  9.  It  retains  life  longer  than  any 
other  part — Experiments  disproving  Haller’s  opinion  on  this 
subject,  11. 

§V.  Of  Life. 

Consists  of  a number  of  phenomena  proportioned  to  the  com- 
plication of  the  organization,  1 1.  Simple  in  plants,  in  which  its 
actions  are  limited  to  nutrition  and  reproduction,  12.  Of  life  in 
the  polypus;  this  animal,  consisting  merely  of  a sentient  and  con- 
tractile pulp,  shaped  into  an  alimentary  cavity,  13.  Of  life  in 
worms,  14 — in  crustaceous  animals,  its  apparatus  more  perfect, 
15.  Of  life  in  cold-blooded  animals,  15.  In  warm-blooded  animals 
and  in  man,  16.  General  view  of  the  human  organization,  17.  Of 
the  elementary  fibre,  19.  Dependence  of  life  on  the  oxydation  of 
the  blood  in  the  lungs,  and  on  the  distribution  of  this  vivified 
blood,  throughout  the  organs,  19. 

§ VI.  Of  the  Vital  Properties;  Sensibility  and  Contractility. 

These  two  properties  not  possessed,  in  an  equal  degree,  by  all 
living  bodies,  21.  Modifications  of  sensibility  in  different  organs, 
26.  Observations  on  the  contractility  of  serous  membranes,  27. 
Caloricity,  27.  Laws  of  sensibility,  29.  Influence  of  sleep,  of  cli- 
mate, of  the  seasons,  of  the  age,  &c.  on  the  vital  properties, 
33—35. 


§ VII.  Of  Sympathies. 

Of  sympathy,  35.  Diseases  arising  from  association;  Syner- 
gies, 38. 

§VIII.  Of  Habit. 

Of  habit,  40.  It  uniformly  lessens  physical  sensibility — A cu- 
rious fact  showing  the  effects  of  habit,  41.  Habit  impairs  the 
sensitive  power  but  improves  the  judgment,  44. 

IX.  Of  the  Vital  Principle. 

The  vital  principle,  not  a being  existing  by  itself,  and  indepen- 
dently of  the  actions  by  which  it  manifests  itself,  46.  A perpe- 
tual struggle  in  organized  bodies,  between  the  laws  of  the  vital 
principle  and  those  of  universal  nature,  48.  The  vital  principle 
resists  the  laws  of  chemistry,  of  physics  and  mechanics,  48, 
There  takes  place,  however,  in  the  animal  economy,  chemical, 
physical  and  mechanical  phenomena,  but  they  are  always  modi- 


INDEX. 


613 

fied  by  the  vital  principle,  48.  Influence  of  the  stature  on  the 
energy  of  the  vital  powers  and  even  on  longevity,  49.  Vis  medi- 
catrix  naturae,  52.  Theory  of  inflammation,  52.  Analogy  between 
the  turgescence  of  an  inflamed  part,  and  of  one  in  a state  of  erec- 
tion, as  the  penis,  &c.  54.  Indirectly  tonic  influence  of  cold,  56. 

§ X.  Of  the  System  of  the  Great  Symfiathetic  JVerves, 

These  nerves  are  to  be  considered  as  connecting  the  organs  of 
the  functions  of  assimilation,  as  the  cerebral  nerves  unite  that  of 
the  external  functions,  56.^  They  are  the  only  nerves  found  in 
several  animals  without  vertebr*.  They  arise  from  all  the  verte- 
bral nerves,  from  which  they  receive  filaments,  as  well  as  from 
the  fifth  and  sixth  cerebral  pairs,  57.  Ganglions  of  the  sympa- 
thetic nerves;  the  semi-lunar  ganglion,  the  principal,  57.  The 
great  sympathetics  render  the  internal  organs  independent  of 
the  will,  51. 

§ XI.  Of  the  relations  of  Physiology  to  several  other  Sciences. 

The  relation  of  physiology  to  physics,  chemistry,  and  mecha- 
nics. Connexion  of  physiology  with  human  and  comparative  ana- 
tomy, 63,  68.  Its  connexion  with  medicine,  70. 

§ XII.  Classif  cation  of  the  Vital  Functions. 

The  best  divisions  of  the  vital  functions  is  that  which  was  first 
pointed  out  by  Aristotle,  adopted  by  Buffon,  and  completely  de- 
veloped by  Grimaud,  7 1 . Modifications  of  which  this  division  is 
susceptible;  preservative  functions  of  the  individual  or  of  the 
species,  73.  These  two  great  divisions  further  divided  into  two 
orders,  73,  Why  man  is  subject  to  more  diseases  than  animals, 
76. 

Of  the  arrangement  of  this  work,  79.  The  voice  is  a natural 
connexion  between  the  preservative  functions  of  the  individual 
and  those  of  the  species,  80.  The  history  of  the  ages  and  tempe- 
raments, and  of  the  varieties  of  the  human  species;  the  account 
of  death  and  putrefaction  forms  a separate  appendix,  81. 


614 


INDEX. 


FIRST  CLASS. 

Functions  subservient  to  the  preservation  of  the  Individual, 

ORDER  FIRST. 

Functions  of  Assimilation, 

CHAPTER  I. 

On  Digestion, 

Definition  of  this  function,  85.  General  considerations  on  the 
digestive  apparatus,  85.  Connexion  between  the  nature  of  the 
aliment  and  the  extent  of  the  digestive  tube,  86.  Of  aliments,  87’. 
The  nutrient  principle  obtained  from  the  aliment,  by  our  organs, 
is  always  the  same,  88.  Of  the  nature  of  the  alimentary  princi- 
ple, 88.  Differences  of  regimen,  according  to  the  climate,  89. 
Hunger  and  thirst,  91 — 94.  Mastication,  95.  Action  of  the  lips, 
of  the  cheeks,  of  the  tongue,  of  the  teeth,  of  the  jaws,  95 — 99. 
The  salivary  solution,  99.  Deglutition,  its  mechanism,  101.  De- 
glutition of  fluids  and  of  gaseous  substances,  102.  Of  the  abdo- 
men, 103.  Of  digestion  in  the  stomach,  104.  Different  systems  of 
digestion;  of  concoction,  fermentation,  106.  Of  putrefaction,  108. 
Of  trituration;  of  digestion  in  granivorous  fowls,  109.  Of  mace- 
ration, 1 10.  Phenomena  of  rumination,  1 1 1 . Of  the  gastric  juice, 
112  Its  source,  its  quantity,  and  solvent  qualities,  114 — 115. 
Digestion  chiefly  consists  in  the  solution  of  the  aliment  in  this 
fluid,  116.  Singular  case  ofa  fistula  of  the  stomach,  117  Action 
of  the  stomach,  120.  Functions  of  the  pylorus,  121.  Of  vomiting, 
124.  Digestion  in  the  duodenum,  125.  Of  the  bile  and  its  secre- 
tory organs,  127.  Circulation  of  the  blood  in  the  liver,  128.  Uses 
of  the  spleen,  130.  Of  the  pancreas  and  pancreatic  juice,  131. 
Separation  of  the  alimentary  matter  into  two  substances,  the  one 
chylous,  the  other  excrementitious,  132.  Of  the  action  in  the 
small  intestines,  133.  The  uses  of  their  curvatures  and  valvulas 
conniven-tes;  of  the  peristaltic  motion,  134.  Of  digestion  in  the 
great  intestines,  135.  Uses  of  the  appendicula  vermiformis  of  the 
caecum.  Of  the  evacuation  of  the  faeces,  136,  137.  Intestinal 
gases,  139. 

Of  the  secretion  and  excretion  of  the  urine,  140.  Of  the  cali- 
ber of  the  renal  arteries,  structure  of  the  kidneys,  140,141. 
Action  of  the  kidneys  and  ureters,  143.  Accumulation  of  the 


INDEX. 


615 

urine  within  the  bladder,  144.  In  what  manner  it  is  expelled, 
146.  Physical  qualities  of  the  urine,  148.  Chemical  analysis  of 
this  fluid,  urea,  149.  Its  retention  produces  urinous  fever,  150. 
Experiments  on  the  effects  attending  retention  of  urine  by  tying 
the  ureters,  in  living  animals,  151.  Urinary  calculi,  why  most 
frequent  in  cold  and  damp  climates,  155. 

CHAPTER  II. 

Of  Absorfition. 

Absorption  takes  place,  in  every  part  of  the  body,  both  on  its 
surface  and  in  its  internal  parts,  157.  Absorption  more  or  less 
active  in  different  circumstances,  159.  Its  activity  is  very  slight 
on  the  external  surface,  except  where  the  skin  is  thin  and  the 
epidermis  moist,  1 60. 

Absorbing  mouths,  163.  Their  mode  of  action,  in  absorption, 
163.  Of  the  lymphatics,  164.  Their  innumerable  anastomoses, 
from  the  union  of  which  there  is  formed  a mesh-work  enveloping 
the  whole  body,  166.  Pathological  inferences. 

Of  the  conglobate  glands,  167.  Their  action,  168.  Circulation 
of  the  lymph,  168.  Observations  on  cancer,  170. 

Of  the  thoracic  duct,  172.  Of  the  physical  and  chemical  pro- 
perties of  the  lymph,  173. 

CHAPTER  III. 

Of  the  Circulation. 

Definition  and  general  idea  of  this  function,  175.  Of  the  action 
of  the  heart;  uses  of  the  pericardium,  176.  Connexion  between 
the  bulk  of  the  heart,  and  strength  and  courage,  177.  Singular 
case  of  communication  between  the  two  ventricles,  179.  Struc- 
ture of  the  heart,  181.  Action  of  the  heart,  in  circulation,  181. 
Decurtation  and  pulsation  of  the  heart,  every  time  the  ventricles 
contract,  182 — 184.  The  quantity  of  blood  which  these  cavities 
send  out,  along  the  arteries,  185. 

Action  of  the  arteries,  186;  their  arrangment  and  anasto- 
moses, 187.  Of  the  structure  of  the  arteries,  the  force  and  con- 
tractility of  their  different  coats,  188.  Dilatation  of  the  arteries, 
194.  Of  the  pulse  and  its  varieties,  196.  Velocity  of  the  circula- 
tion along  the  arteries. 

Of  the  capillary  vessels,  199.  Those  which  convey  a colourless 
fluid,  199.  Of  the  manner  in  which  the  blood  flows  along  these 
vessels,  200.  Terminations  of  the  arterial  system,  203. 


616 


INDEX. 


Of  the  action  of  the  veins,  204.  Proportion  of  the  arterial  to 
the  venous  blood;  difference  of  arrangement  and  structure  be- 
tween the  arteries  and  veins,  204—205.  Of  the  use  of  the  valves 
of  the  veins,  206.  Gradual  increase  of  velocity  in  the  venous  cir- 
culation. Of  the  use  of  the  vena  azygos,  208.  Reflux  of  the  blood 
in  the  great  venous  trunks,  208,  209.  Theory  of  the  circulation, 

210.  Partial  circulations  in  the  midst  of  the  general  circulation, 

211.  Of  the  two  divisions,  venous  and  arterial,  of  the  circle  of 
circulation,  212.  Organs  situated  on  the  two  points  of  intersec- 
tion of  this  great  circle,  212,  213. 

CHAPTER  IV. 

Of  Resfiiration. 

Of  all  the  changes  which  the  blood  undergoes,  in  penetrating 
through  the  organs  placed  in  the  course  of  the  circulation,  the 
most  remarkable  are  those  it  receives  from  respiration,  214. 
Differences  of  arterial  and  venous  blood,  214.  Of  the  atmosphere, 
214.  Action  by  which  respiration  is  performed,  222.  Motions  of 
the  ribs,  224.  Diflicult  respiration,  226.  Structure  of  the  lungs, 
227,  228.  Use  of  the  bronchial  arteries,  228.  Pulmonary  inflam- 
mations, 229.  Changes  on  the  air  and  on  the  blood  by  respira- 
tion, 231,  232.  Vitality  of  the  lungs,  236.  Respiration  of  cer- 
tain animals,  236.  Division  or  ligature  of  the  eighth  pair  of 
nerves,  238. 

Of  animal  heat,  239.  Animal  heat  is  independent  of  the  media 
in  which  animated  beings  live,  239.  The  heat  of  the  animal  body 
thirty-two  degrees,  239.  The  lungs  not  the  only  parts  in  which 
caloric  is  disengaged,  242.  Caloric  evolved,  to  a certain  degree, 
in  all  organs  receiving  arterial  blood,  243.  Cutaneous  evapora- 
tion, the  most  powerful  means  of  lowering  the  temperature,  245. 
It  does  not  explain,  however,  why  the  animal  temperature  re- 
mains the  same,  in  a medium  hotter  than  the  body;  case  of  a man 
said  to  be  incombustible,  245,  246.  Effects  of  cold,  247,  248. 

Phenomena  of  the  circulation  of  the  blood  through  the  lungs, 
249.  Pulmonary  exhalation,  250.  Of  asphyxia,  from  drowning 
and  from  strangulation,  252.  From  noxious  gases  and  from  in- 
toxication, 254.  From  obstruction  of  the  glottis;  of  the  asphyxia 
of  new  born  children,  255. 

Of  several  phenomena  of  respiration,  as  sighing,  yawning, 
sneezing,  coughing,  hiccup,  and  laughter,  256.  Cutaneous  per- 
spiration, 257.  Its  connexion  with  the  other  functions,  258.  Its 


INDEX. 


617 

quantity,  259.  Of  the  sweat;  of  the  formation  of  carbonic  acid 
gas  on  the  surface  of  the  skin,  261.  Of  the  uses  of  the  cutaneous 
perspiration,  261. 

CHAPTER  V. 

Of  the  Secretions. 

Classification  of  the  animal  fluids,  262.  Chemical  classification 
of  the  fluids  by  Fourcroy,  the  best,  262.  Of  the  blood.  Of  its  phy- 
sical, chemical,  and  vital  properties,  264 — 266.  Of  sanguifica- 
tion, 266.  Of  the  effects  of  regimen  on  the  blood,  268.  The 
transfusion  of  blood,  270. 

Of  the  secretory  apparatus,  272.  Serous  transudation,  273. 
Secretion  in  the  mucous  follicles,  274.  In  the  conglomerate 
glands,  275.  Of  accidental  secretions,  276.  Influence  of  the 
nervous  energy  on  the  secretions,  279,  280.  Influence  of  the 
imagination  on  the  secretions,  285.  Quantity  of  fluids  secreted, 
285. 

Secretion  of  adeps  within  the  cellular  tissue,  286.  Difference 
of  quantity  and  quality  of  this  fluid,  in  the  different  parts  of  the 
body,  286.  Of  the  uses  of  adeps,  288  Circumstances  which  in- 
crease or  lessen  its  secretion,  290.  Analogy  of  the  marrow  of  the 
bones  to  adeps,  291.  Of  the  insensibility  of  the  medullary  mem- 
brane, 291. 

CHAPTER  VI. 

Of  Nutrition. 

Nutrition  is  the  completement  of  assimilation,  292.  Period  of 
the  complete  renovation  of  the  body,  293.  Mechanism  of  nutri- 
tion; from  arterial  blood  only,  293.  Difference  of  vegetable  and 
animal  substances,  294.  New  products,  295.  Of  the  emunctories, 
298.  General  view  of  the  functions  of  nutrition,  299. 

CHAPTER  VII. 

Of  Sensations. 

Functions  that  are  subservient  to  the  preservation  of  the  indivi- 
dual, by  connecting  him  with  surrounding  beings.  Of  sensations, 
303  Natural  succession  of  the  phenomena  of  sense,  304. 

Of  light  and  of  colours,  304.  Organ  of  sight,  306 — formed  of 
three  distinct  parts,  306.  Use  of  the  eyelids,  eye-lashes,  and 
lachrymal  ducts,  307,  309.  Eye-ball,  its  structure,  311.  Mecha- 

41 


INDEX. 


618 

nism  and  phenomena  of  vision,  315.  Motions  of  the  iris,  315.  Re- 
fraction of  the  rays  of  light  by  the  membrane,  316,  and  by  the 
fluids  of  the  eye;  inversion  of  objects  on  the  retina;  point  of  dis- 
tinct vision,  316  Defects  of  vision,  318.  Development  of  the  eyes, 
and  their  motions,  319.  Errors  of  vision,  321.  Its  difference  in 
different  animals,  322. 

Organ  of  hearing,  323.  Of  sound,  324.  Structure  of  the  ear, 
and  mechanism  of  hearing,  325.  Differences  in  animals,  328. 
Defects  of  hearing,  329. 

Of  odours,  331.  Organ  of  smell,  332.  Sensation  of  smell,  333. 

Of  taste,  336.  Of  the  tastes  of  different  substances,  organ  of 
taste,  336.  In  different  animals,  336,  337.  Uses  of  the  nerves  of 
the  tongue,  338.  Galvanic  experiments  on  this  subject,  338. 

Of  touch,  339.  Its  certainty  and  errors,  339.  Of  the  integu- 
ments, 340.  Of  the  nails,  345.  Of  the  hair,  346.  Of  the  hand,  350. 
Touch  in  different  animals,  252. 

Of  the  nerves,  352.  Of  their  origin  in  sensible  parts,  353.  Of 
their  structure,  353,  354.  Opinion  of  Reil  on  this  subject,  354. 
Of  the  manner  they  arise  from  each  other,  355.  Of  their  termi- 
nation in  the  brain,  355.  Of  their  comparative  size,  in  different 
animals,  and  in  man  at  different  ages,  356,  357. 

Of  the  coverings  of  the  brain,  356.  Mechanism  of  the  bones  of 
the  skull  and  face,  358  Uses  of  the  sphenoid,  358.  Rounded 
form  of  the  skull,  362.  Uses  of  the  dura  mater,  of  the  arachnoid, 
and  the  pia  mater,  362,  363.  Size  of  the  brain.  363.  Form  of  the 
head,  364.  Connexion  with  the  intellectual  powers,  365.  Nerves 
crossing,  366.  Divergent  and  convergent  fibres,  367,  368.  Cere- 
bral circulation,  369.  Arterial  blood  retarded,  370.  Jugular  veins, 
370.  Connexion  of  the  actions  of  the  brain  and  heart,  371.  Theory 
of  syncope,  373.  Motions  of  the  brain,  377.  Experiments,  378, 
384  Action  of  the  nerves  and  brain,  387.  Principle  of  motion  and 
sensation,  389.  Different  intellectual  functions  of  different  parts 
of  the  brain,  390,  Not  yet  perfectly  understood,  390. 

Analysis  of  the  understanding,  390.  Perception,  391.  Reason- 
ing and  instinct,  392.  Generation  of  the  faculties,  392,  393'.  Sen- 
sation, perception,  attention,  memory,  imagination,  association 
of  ideas,  comparison,  judgment,  reasoning,  394,  396.  Influence 
of  signs  on  the  faculties  of  thought,  397.  Analysis  of  ideas,  by 
M.  Destutt  Tracy,  400.  Derangements  of  the  mind,  401.  Mania, 
402.  Idiotcy,  403. 

Of  the  passions,  407.  State  of  the  intellectual  powers  connect- 
ed with  them,  407.  Eft’ects  on  the  animal  economy,  408.  Of  sleep 


INDEX. 


619 


and  waking,  409.  Repose  of  the  functions  which  connect  us  with 
surrounding  objects;  condition  of  ,the  functions  of  assimilation, 
during  sleep,  409.  Proximate  cause  of  sleep,  4 1 2.  Of  dreams  and 
somnambulism,  414.  Animals  are  also  subject  to  dreams,  415. 

CHAPTER  VIII. 

Of  Motions. 

This  chapter  treats  only  of  voluntary  motions,  whose  organs 
may  be  distinguished  into  active  and  passive  (the  bones  and  the 
muscles),  4)7.  Structure  and  properties  of  muscular  fibres,  418. 
Of  the  tendons  and  aponeuroses,  419,  420.  Phenomena  of  mus- 
cular contraction  determined  by  an  act  of  the  will,  421.  A sound 
state  of  the  nerves,  arteries,  and  veins  belonging  to  a muscle,  is 
necessary  to  its  action,  421.  Theory  of  this  action,  42?.  Prepon- 
derance of  the  flexor  muscles  over  the  extensors,  423.  This  pre- 
ponderance varies,  according  to  the  age,  the  state  of  health  or 
disease,  425.  Of  the  power  of  the  muscles;  it  bears  a proportion 
to  the  number  of  their  fibres,  428.  The  degree  of  decurtation 
of  which  they  are  capable  is  proportioned  to  the  length  of  their 
fibres,  429.  Direction  of  the  motions  performed  by  the  action  of 
the  muscles,  429,  430.  Of  muscular  flesh,  433.  Galvanism,  434. 
Volta’s  apparatus  or  galvanic  pile,  439.  Effects  of  galvanism,  in 
the  treatment  of  disease,  442.  General  view  of  the  osseous  sys- 
tem, 448.  Of  the  vertebral  column;  it  forms  the  most  essential 
part  of  the  skeleton,  444.  Difference  of  the  stature,  at  different 
times  of  the  day,  446.  Of  the  lower  limbs,  447.  Structure  of  the 
bones,  444.  Uses  of  the  periosteum,  and  of  the  marrow,  451. 
Theory  of  necrosis,  451,  452.  Of  the  articulations,  453.  Of  the 
articulating  cartilages,  454.  Of  the  synovia,  454.  Theory  of  an- 
chylosis, 455. 

Of  animal  mechanics;  of  standing,  457.  Of  the  centre  of  gra- 
vity, 457.  Tendency  of  the  body  to  fall,  458.  Standing  is  per- 
formed by  an  effort  of  the  extensor  muscles,  459.  Reasons  why 
it  is  impossible  for  anew  born  child  to  stand,  461.  Man  is  the 
only  animal  that  can  stand  upright,  464.  Of  falls,  468.  Of  stand- 
ing on  one  foot,  469.  A degree  of  separation  of  the  feet  necessary 
in  standing,  469.  Of  kneeling;  of  sitting;  of  the  recumbent  pos- 
ture, 470.  Of  lying  on  the  sides,  471.  Of  the  prone  and  supine 
postures,  472,  473.  The  different  modes  of  the  recumbent  pos- 
ture have  a reference  to  the  degrees  of  facility  of  respiration  and 
to  the  period  of  life,  473,  474.  Recumbent  posture,  on  an  inclined 


620 


INDEX. 


plane,  necessary,  especially  to  old  people,  474.  Of  motions  of 
progression;  of  walking,  475.  Of  walking  up  or  down  an  inclined 
surface,  477.  Mechanism  of  the  articulation  between  the  leg  and 
foot,  478.  Of  running,  480.  Of  leaping,  482.  Leaping  is  per- 
formed by  the  sudden  extension  of  the  lower  extremities,  pre- 
viously in  a state  of  flexion,  482.  Of  the  vertical  and  oblique  leap, 
484,  485.  Of  swimming;  man  swims  with  difficulty,  485.  Swim- 
ming natural  and  easy  to  fishes;  its  mechanism,  486.  Of  flying, 
487.  The  structure  of  the  body  in  birds  favourable  to  this  action; 
how  performed,  487,  488.  Of  crawling,  490.  All  the  phenomena 
of  animal  mechanics  may  be  referred  to  the  theory  of  the  lever 
of  the  third  kind,  490.  Partial  motions  performed  by  the  upper 
extremities,  492.  Of  climbing;  of  pushing,  493.  Of  throwing  a 
projectile,  494.  Partial  motions,  as  signs  expressive  of  ideas, 
496.  Of  gestures  and  attitudes,  496. 

CHAPTER  IX. 

Of  Voice  and  Speech. 

Definition  of  the  voice  and  of  speech;  circumstances  necessary 
to  the  formation  of  the  voice;  its  organs,  497.  Opinions  of  Fer- 
rein  and  Dodart,  on  the  uses  of  the  glottis,  498.  The  larnyx  is, 
at  once,  a wind  and  a stringed  instrument,  499.  Of  the  power  of 
the  voice;  of  speech;  man  alone  is  capable  of  speech,  501.  Of  the 
vowels  and  consonants,  501,  502.  Of  song  and  music,  503.  Of 
stammering,  burr,  and  dumbness,  504.  Instruction  of  the  deaf 
and  dumb,  506.  Ventriloquism,  506. 

SECOND  CLASS. 

CHAPTER  X. 

Functions  subservient  to  the  preservation  of  the  Species. 

Differences  of  the  sexes,  511.  Case  in  which  the  sexual  organs 
did  not  exist,  512.  Hermaphrodism  is  never  met  tvith  in  the  hu- 
man species.  Man,  in  the  exercise  of  the  functions  of  generation, 
not  under  the  control  of  the  seasons,  5 15.  Of  the  organs  of  gene- 
ration, in>man,  515.  Of  the  female  organs  of  generation,  5 18.  Of 
the  signs  of  virginity,  520. 

Of  erection,  521.  Of  the  human  semen,  522.  Of  the  ovaria, 
525.  Of  the  impregnation  of  the  ovum,  529.  Of  barrenness,  531. 
Systems  of  generation,  532.  Gestation,  534.  Of  the  foetus  and  its 
coverings,  539.  Of  the  development  of  its  organs,  540.  Of  the 


INDEX. 


621 

circulation  of  the  blood,  in  the  fetus,  542.  Of  the  placenta,  542. 
The  umbilical  cord,  545.  Mode  of  existence  of  the  fetus,  547. 
Morbid  affections  to  which  it  is  subject  while  in  the  womb,  549. 
Of  monsters,  549.  Their  different  kinds,  and  the  causes  which 
produce  them,  550.  History  of  a remarkable  case,  550.  Of  the 
chorion,  of  the  amnion  and  liquor  amnii,  552.  Of  the  allantois 
and  urachus,  553.  Of  the  natural  term  of  gestation,  554.  Of  par- 
turition, 554.  Of  the  mechanism  of  parturition,  555.  Of  twins, 

558.  The  number  of  male  children  born  exceeds  that  of  female, 

559.  Ofsuperfoetations,  559.  Of  suckling,  561.  Sympathy  between 
the  uterus  and  mammae;  structure  of  the  latter,  561,  562.  The 
milk  appears  to  be  brought  to  the  breasts  by  the  lymphatics,  564. 
Chemical  qualities  of  the  milk,  566.  Connexion  between  the  new 
born  child  and  the  mother,  568.  Imperfect  development  of  the 
fcetal  lungs,  569. 

CHAPTER  XI. 

Containing  the  History  of  the  ^ges,  the  Temfieraments^  and  the 
Varieties  of  the  Human  S/iecies;  of  Death  and  Putrefaction. 

Of  infancy;  of  dentition,  571.  Ossification,  573.  Phenomena  of 
puberty,  574.  Connexion  between  the  development  of  the  sexual 
organs  and  the  voice,  575.  Of  menstruation,  575.  Of  the  cause 
of  menstruation,  577,  578.  Of  the  cessation  of  this  evacuation, 
578.  Of  manhood,  579.  Of  temperaments  and  idiosyncrasies,  579. 
Of  the  sanguine  temperament,  580.  Of  the  muscular  or  athletic 
temperament,  582.  Of  the  bilious  temperament,  produced  by  an 
increased  energy  of  the  hepatic  system,  joined  to  considerable 
activity  of  the  sanguineous  system,  583.  Of  the  melancholic 
temperament,  584.  Lymphatic  temperament,  589.  Nervous,  589. 
Mixed  and  acquired  temperaments,  591.  Influence  of  climate  on 
temperaments,  591. 

Varieties  of  the  human  species,  593.  European  Arab  race,  594. 
Negro,  595.  Mogul,  595.  Hyperborean,  595.  Moral  characte- 
ristics of  the  diffeient  races,  596.  Giants  and  dwarfs,  597. 

Of  old  age  and  decrepitude,  598.  Decay,  598.  Death,  601. 
Gradual  extinction  of  bodily  and  mental  powers,  in  the  reversed 
order  of  their  production,  602.  Period  of  death,  603.  Probabilities 
of  human  life,  604.  Of  putrefaction,  607. 


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